18F-Sodium Fluoride Positron Emission Tomography and Computed Tomography in Acute Aortic Syndrome

BackgroundAcute aortic syndrome is associated with aortic medial degeneration. ¹⁸F-sodium fluoride (¹⁸F-NaF) positron emission tomography (PET) detects microscopic tissue calcification as a marker of disease activity.ObjectivesIn a proof-of-concept study, this investigation aimed to establish whether ¹⁸F-NaF PET combined with computed tomography (CT) angiography could identify aortic medial disease activity in patients with acute aortic syndrome.MethodsPatients with aortic dissection or intramural hematomas and control subjects underwent ¹⁸F-NaF PET/CT angiography of the aorta. Aortic ¹⁸F-NaF uptake was measured at the most diseased segment, and the maximum value was corrected for background blood pool activity (maximum tissue-to-background ratio [TBR_max]). Radiotracer uptake was compared with change in aortic size and major adverse aortic events (aortic rupture, aorta-related death, or aortic repair) over 45 ± 13 months.ResultsAortic ¹⁸F-NaF uptake co-localized with histologically defined regions of microcalcification and elastin disruption. Compared with control subjects, patients with acute aortic syndrome had increased ¹⁸F-NaF uptake (TBR_max: 1.36 ± 0.39 [n = 20] vs 2.02 ± 0.42 [n = 47] respectively; P < 0.001) with enhanced uptake at the site of intimal disruption (+27.5%; P < 0.001). ¹⁸F-NaF uptake in the false lumen was associated with aortic growth (+7.1 mm/year; P = 0.011), and uptake in the outer aortic wall was associated with major adverse aortic events (HR: 8.5 [95% CI: 1.4-50.4]; P = 0.019).ConclusionsIn patients with acute aortic syndrome, ¹⁸F-NaF uptake was enhanced at sites of disease activity and was associated with aortic growth and clinical events. ¹⁸F-NaF PET/CT holds promise as a noninvasive marker of disease severity and future risk in patients with acute aortic syndrome. (¹⁸F Sodium Fluoride PET/CT in Acute Aortic Syndrome [FAASt]; NCT03647566)     

Diagnostic Value of 18F-Fluorodeoxyglucose Positron Emission Tomography Computed Tomography in Prosthetic Pulmonary Valve Infective Endocarditis

ObjectivesThe aim of this study was to assess the diagnostic performances of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) in congenital heart disease (CHD) patients with pulmonary prosthetic valve or conduit endocarditis (PPVE) suspicion.BackgroundPPVE is a major issue in the growing CHD population. Diagnosis is challenging, and usual imaging tools are not always efficient or validated in this specific population. Particularly, the diagnostic yield of ¹⁸F-FDG PET/CT remains poorly studied in PPVE.MethodsA retrospective multicenter study was conducted in 8 French tertiary centers. Children and adult CHD patients who underwent ¹⁸F-FDG PET/CT in the setting of PPVE suspicion between January 2010 and May 2020 were included. The cases were initially classified as definite, possible, or rejected PPVE regarding the modified Duke criteria and finally by the Endocarditis Team consensus. The result of ¹⁸F-FDG PET/CT had been compared with final diagnosis consensus used as gold-standard in our study.ResultsA total of 66 cases of PPVE suspicion involving 59 patients (median age 23 years, 73% men) were included. Sensitivity, specificity, positive predictive value, and negative predictive value of ¹⁸F-FDG PET/CT in PPVE suspicion were respectively: 79.1% (95% CI: 68.4%-91.4%), 72.7% (95% CI: 60.4%-85.0%), 91.9% (95% CI: 79.6%-100.0%), and 47.1% (95% CI: 34.8%-59.4%). ¹⁸F-FDG PET/CT findings would help to correctly reclassify 57% (4 of 7) of possible PPVE to definite PPVE.ConclusionsUsing ¹⁸F-FDG PET/CT improves the diagnostic accuracy of the Duke criteria in CHD patients with suspected PPVE. Its high positive predictive value could be helpful in routine to shorten diagnosis and treatment delays and improve clinical outcomes.     

Diagnostic Accuracy of Cardiac Computed Tomography and 18-F Fluorodeoxyglucose Positron Emission Tomography in Cardiac Masses

ObjectivesThis study sought to assess the diagnostic accuracy of cardiac computed tomography (CT) and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) with positron emission tomography/computed tomography (PET/CT) in defining the nature of cardiac masses.BackgroundThe diagnostic accuracy of cardiac CT and ¹⁸F-FDG PET/CT in identifying the nature of cardiac masses has been analyzed to date only in small samples.MethodsOf 223 patients with echocardiographically diagnosed cardiac masses, a cohort of 60 cases who underwent cardiac CT and ¹⁸F-FDG PET/CT was selected. All masses had histological confirmation, except for a minority of thrombotic formations. For each mass, 8 morphological CT signs, standardized uptake value (SUV_max, SUV_mean), metabolic tumor volume, and total lesion glycolysis in ¹⁸F-FDG PET were used as diagnostic markers.ResultsIrregular tumor margins, pericardial effusion, invasion, solid nature, mass diameter, CT contrast uptake, and pre-contrast characteristics were strongly associated with the malignant nature of masses. The coexistence of at least 5 CT signs perfectly identified malignant masses, whereas the detection of 3 or 4 CT signs did not accurately discriminate the masses’ nature. The mean SUV_max, SUV_mean, metabolic tumor volume, and total lesion glycolysis values were significantly higher in malignant than in benign masses. The diagnostic accuracy of SUV, metabolic tumor volume, and total lesion glycolysis ¹⁸F-FDG PET/CT parameters was excellent in detecting malignant masses. Among patients with 3 or 4 pathological CT signs, the presence of at least 1 abnormal ¹⁸F-FDG PET/CT parameter significantly increased the identification of malignancies.ConclusionsCardiac CT is a powerful tool to diagnose cardiac masses as the number of abnormal signs was found to correlate with the lesions’ nature. Similarly, ¹⁸F-FDG PET/CT accurately identified malignant masses and contributed with additional valuable information in diagnostic uncertainties after cardiac CT. These imaging tools should be performed in specific clinical settings such as involvement of great vessels or for disease-staging purposes.     

Bioprosthetic Aortic Valve Leaflet Thickening in the Evolut Low Risk Sub-Study

BackgroundSubclinical leaflet thrombosis has been reported after bioprosthetic aortic valve replacement, characterized using 4-dimensional computed tomographic imaging by hypoattenuated leaflet thickening (HALT) and reduced leaflet motion (RLM). The incidence and clinical implications of these findings remain unclear.ObjectivesThe aim of this study was to determine the frequency, predictors, and hemodynamic and clinical correlates of HALT and RLM after aortic bioprosthetic replacement.MethodsA prospective subset of patients not on oral anticoagulation enrolled in the Evolut Low Risk randomized trial underwent computed tomographic imaging 30 days and 1 year after transcatheter aortic valve replacement (TAVR) or surgery. The primary endpoint was the frequency of HALT at 30 days and 1 year, analyzed by an independent core laboratory using standardized definitions. Secondary endpoints included RLM, mean aortic gradient, and clinical events at 30 days and 1 year.ResultsAt 30 days, the frequency of HALT was 31 of 179 (17.3%) for TAVR and 23 of 139 (16.5%) for surgery; the frequency of RLM was 23 of 157 (14.6%) for TAVR and 19 of 133 (14.3%) for surgery. At 1 year, the frequency of HALT was 47 of 152 (30.9%) for TAVR and 33 of 116 (28.4%) for surgery; the frequency of RLM was 45 of 145 (31.0%) for TAVR and 30 of 111 (27.0%) for surgery. Aortic valve hemodynamic status was not influenced by the presence or severity of HALT or RLM at either time point. The rates of HALT and RLM were similar after the implantation of supra-annular, self-expanding transcatheter, or surgical bioprostheses.ConclusionsThe presence of computed tomographic imaging abnormalities of aortic bioprostheses were frequent but dynamic in the first year after self-expanding transcatheter and surgical aortic valve replacement, but these findings did not correlate with aortic valve hemodynamic status after aortic valve replacement in patients at low risk for surgery. (Medtronic Evolut Transcatheter Aortic Valve Replacement in Low Risk Patients; NCT02701283)     

Vascular Positron Emission Tomography and Restenosis in Symptomatic Peripheral Arterial Disease: A Prospective Clinical Study

ObjectivesThis study determined whether in vivo positron emission tomography (PET) of arterial inflammation (¹⁸F-fluorodeoxyglucose [¹⁸F-FDG]) or microcalcification (¹⁸F-sodium fluoride [¹⁸F-NaF]) could predict restenosis following PTA.BackgroundRestenosis following lower limb percutaneous transluminal angioplasty (PTA) is common, unpredictable, and challenging to treat. Currently, it is impossible to predict which patient will suffer from restenosis following angioplasty.MethodsIn this prospective observational cohort study, 50 patients with symptomatic peripheral arterial disease underwent ¹⁸F-FDG and ¹⁸F-NaF PET/computed tomography (CT) imaging of the superficial femoral artery before and 6 weeks after angioplasty. The primary outcome was arterial restenosis at 12 months.ResultsForty subjects completed the study protocol with 14 patients (35%) reaching the primary outcome of restenosis. The baseline activities of femoral arterial inflammation (¹⁸F-FDG tissue-to-background ratio [TBR] 2.43 [interquartile range (IQR): 2.29 to 2.61] vs. 1.63 [IQR: 1.52 to 1.78]; p < 0.001) and microcalcification (¹⁸F-NaF TBR 2.61 [IQR: 2.50 to 2.77] vs. 1.69 [IQR: 1.54 to 1.77]; p < 0.001) were higher in patients who developed restenosis. The predictive value of both ¹⁸F-FDG (cut-off TBR_max value of 1.98) and ¹⁸F-NaF (cut-off TBR_max value of 2.11) uptake demonstrated excellent discrimination in predicting 1-year restenosis (Kaplan Meier estimator, log-rank p < 0.001).ConclusionsBaseline and persistent femoral arterial inflammation and micro-calcification are associated with restenosis following lower limb PTA. For the first time, we describe a method of identifying complex metabolically active plaques and patients at risk of restenosis that has the potential to select patients for intervention and to serve as a biomarker to test novel interventions to prevent restenosis.     

Detection and Characterization of Thrombosis in Humans Using Fibrin-Targeted Positron Emission Tomography and Magnetic Resonance

ObjectivesThe authors present a novel technique to detect and characterize LAA thrombus in humans using combined positron emission tomography (PET)/cardiac magnetic resonance (CMR) of a fibrin-binding radiotracer, [⁶⁴Cu]FBP8.BackgroundThe detection of thrombus in the left atrial appendage (LAA) is vital in the prevention of stroke and is currently performed using transesophageal echocardiography (TEE).MethodsThe metabolism and pharmacokinetics of [⁶⁴Cu]FBP8 were studied in 8 healthy volunteers. Patients with atrial fibrillation and recent TEEs of the LAA (positive n = 12, negative n = 12) were injected with [⁶⁴Cu]FBP8 and imaged with PET/CMR, including mapping the longitudinal magnetic relaxation time (T₁) in the LAA.Results[⁶⁴Cu]FBP8 was stable to metabolism and was rapidly eliminated. The maximum standardized uptake value (SUV_Max) in the LAA was significantly higher in the TEE-positive than TEE-negative subjects (median of 4.0 [interquartile range (IQR): 3.0-6.0] vs 2.3 [IQR: 2.1-2.5]; P < 0.001), with an area under the receiver-operating characteristic curve of 0.97. An SUV_Max threshold of 2.6 provided a sensitivity of 100% and specificity of 84%. The minimum T₁ (T_1Min) in the LAA was 970 ms (IQR: 780-1,080 ms) vs 1,380 ms (IQR: 1,120-1,620 ms) (TEE positive vs TEE negative; P < 0.05), with some overlap between the groups. Logistic regression using SUV_Max and T_1Min allowed all TEE-positive and TEE-negative subjects to be classified with 100% accuracy.ConclusionsPET/CMR of [⁶⁴Cu]FBP8 is able to detect acute as well as older platelet-poor thrombi with excellent accuracy. Furthermore, the integrated PET/CMR approach provides useful information on the biological properties of thrombus such as fibrin and methemoglobin content. (Imaging of LAA Thrombosis; NCT03830320)     

Parametric Imaging of Biologic Activity of Atherosclerosis Using Dynamic Whole-Body Positron Emission Tomography

BackgroundFor molecular imaging of atherosclerotic vessel wall activity, tracer kinetic analysis may yield improved contrast versus blood, more robust quantitative parameters, and more reliable characterization of systems biology.ObjectivesThe authors introduce a novel dynamic whole-body positron emission tomography (PET) protocol that is enabled by rapid continuous camera table motion, followed by reconstruction of parametric data sets using voxel-based Patlak graphical analysis.MethodsTwenty-five subjects were prospectively enrolled and underwent dynamic PET up to 90 minutes after injection of 2-[¹⁸F]fluoro-2-deoxy-D-glucose (FDG). Two sets of images were generated: 1) the established standard of static standardized uptake value (SUV) images; and 2) parametric images of the metabolic rate of FDG (MR_FDG) using the Patlak plot–derived influx rate. Arterial wall signal was measured and compared using the volume-of-interest technique, and its association with hematopoietic and lymphoid organ signal and atherosclerotic risk factors was explored.ResultsParametric MR_FDG images provided excellent arterial wall visualization, with elimination of blood-pool activity, and enhanced focus detectability and reader confidence. Target-to-background ratio (TBR) from MR_FDG images was significantly higher compared with SUV images (2.6 ± 0.8 vs 1.4 ± 0.2; P < 0.0001), confirming improved arterial wall contrast. On MR_FDG images, arterial wall signal showed improved correlation with hematopoietic and lymphoid organ activity (spleen P = 0.0009; lymph nodes P = 0.0055; and bone marrow P = 0.0202) and increased with the number of atherosclerotic risk factors (r = 0.49; P = 0.0138), where signal from SUV images (SUV_max P = 0.9754; TBR_max P = 0.8760) did not.ConclusionsAbsolute quantification of MR_FDG is feasible for arterial wall using dynamic whole-body PET imaging. Parametric images provide superior arterial wall contrast, and they might be better suited to explore the relationship between arterial wall activity, systemic organ networks, and cardiovascular risk. This novel methodology may serve as a platform for future diagnostic and therapeutic clinical studies targeting the biology of arterial wall disease.     

Hybrid Cardiac Magnetic Resonance/Fluorodeoxyglucose Positron Emission Tomography to Differentiate Active From Chronic Cardiac Sarcoidosis

ObjectivesThe purpose of this study was to investigate the diagnostic value of simultaneous hybrid cardiac magnetic resonance (CMR) and ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) for detection and differentiation of active (aCS) from chronic (cCS) cardiac sarcoidosis.BackgroundLate gadolinium enhancement (LGE) CMR and FDG-PET are both established imaging techniques for the detection of CS. However, there are limited data regarding the value of a comprehensive simultaneous hybrid CMR/FDG-PET imaging approach that includes CMR mapping techniques.MethodsForty-three patients with biopsy-proven extracardiac sarcoidosis (median age: 48 years, interquartile range: 37-57 years, 65% male) were prospectively enrolled for evaluation of suspected CS. After dietary preparation for suppression of myocardial glucose metabolism, patients were evaluated on a 3-T hybrid PET/MR scanner. The CMR protocol included T1 and T2 mapping, myocardial function, and LGE imaging. We assumed aCS if PET and CMR (ie, LGE or T1/T2 mapping) were both positive (PET+/CMR+), cCS if PET was negative but CMR was positive (PET?/CMR+), and no CS if patients were CMR negative regardless of PET findings.ResultsAmong the 43 patients, myocardial glucose uptake was suppressed successfully in 36 (84%). Hybrid CMR/FDG-PET revealed aCS in 13 patients (36%), cCS in 5 (14%), and no CS in 18 (50%). LGE was present in 14 patients (39%); T1 mapping was abnormal in 10 (27%) and T2 mapping abnormal in 2 (6%). CS was diagnosed based on abnormal T1 mapping in 4 out of 18 CS patients (22%) who were LGE negative. PET FDG uptake was present in 17 (47%) patients.ConclusionsComprehensive simultaneous hybrid CMR/FDG-PET imaging is useful for the detection of CS and provides additional value for identifying active disease. Our results may have implications for enhanced diagnosis as well as improved identification of patients with aCS in whom anti-inflammatory therapy may be most beneficial.     

Long-Term Outcomes of Anticoagulation for Bioprosthetic Valve Thrombosis

BackgroundEarly in the prevention and treatment of bioprosthetic valve thrombosis (BPVT), anticoagulation is effective, but the long-term outcome after BPVT is unknown.ObjectivesThe goal of this study was to assess the long-term outcomes of patients with BPVT treated with anticoagulation.MethodsThis analysis was a matched cohort study of patients treated with warfarin for suspected BPVT at the Mayo Clinic between 1999 and 2017.ResultsA total of 83 patients treated with warfarin for suspected BPVT (age 57 ± 18 years; 45 men [54%]) were matched to 166 control subjects; matching was performed according to age, sex, year of implantation, and prosthesis type and position. Echocardiography normalized in 62 patients (75%) within 3 months (interquartile range [IQR]: 1.5 to 6 months) of anticoagulation; 21 patients (25%) did not respond to warfarin. Median follow-up after diagnosis was 34 months (IQR: 17 to 54 months). There was no difference in the primary composite endpoint between the patients with BPVT and the matched control subjects (log-rank test, p = 0.79), but the former did have a significantly higher rate of major bleeding (12% vs. 2%; p < 0.0001). BPVT recurred (re-BPVT) in 14 (23%) responders after a median of 23 months (IQR: 11 to 39 months); all but one re-BPVT patient responded to anticoagulant therapy. Patients with BPVT had a higher probability of valve re-replacement (68% vs. 24% at 10 years’ post-BPVT; log-rank test, p < 0.001).ConclusionsBPVT was associated with re-BPVT and early prosthetic degeneration in a significant number of patients. Indefinite warfarin anticoagulation should be considered after a confirmed BPVT episode, but this strategy must be balanced against an increased risk of bleeding.     

Prognostic Value of Quantitative Metrics From Positron Emission Tomography in Ischemic Heart Failure

ObjectivesThe aim of this study was to investigate the prognostic and clinical value of quantitative positron emission tomographic (PET) metrics in patients with ischemic heart failure.BackgroundAlthough myocardial flow reserve (MFR) is a strong predictor of cardiac risk in patients without heart failure, it is unknown whether quantitative PET metrics improve risk stratification in patients with ischemic heart failure.MethodsThe study included 254 patients referred for stress and rest myocardial perfusion imaging and viability testing using PET. Major adverse cardiac event(s) (MACE) consisted of death, resuscitated sudden cardiac death, heart transplantation, acute coronary syndrome, hospitalization for heart failure, and late revascularization.ResultsMACE occurred in 170 patients (67%) during a median follow-up of 3.3 years. In a multivariate Cox proportional hazards model including multiple quantitative PET metrics, only MFR predicted MACE significantly (p = 0.013). Beyond age, symptom severity, diabetes mellitus, previous myocardial infarction or revascularization, 3-vessel disease, renal insufficiency, ejection fraction, as well as presence and burden of ischemia, scar, and hibernating myocardium, MFR was strongly associated with MACE (adjusted hazard ratio per increase in MFR by 1: 0.63; 95% confidence interval: 0.45 to 0.91). Incorporation of MFR into a risk assessment model incrementally improved the prediction of MACE (likelihood ratio chi-square test [16] = 48.61 vs. chi-square test [15] = 39.20; p = 0.002).ConclusionsIn this retrospective analysis of a single-center cohort, quantitative PET metrics of myocardial blood flow all improved risk stratification in patients with ischemic heart failure. However, in a hypothesis-generating analysis, MFR appears modestly superior to the other metrics as a prognostic index.     

Antithrombotic Therapy After Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) is a treatment option for symptomatic patients with severe aortic stenosis who are candidates for a bioprosthesis across the entire spectrum of risk. However, TAVR carries a risk for thrombotic and bleeding events, underscoring the importance of defining the optimal adjuvant antithrombotic regimen. Antithrombotic considerations are convoluted by the fact that many patients undergoing TAVR are generally elderly and present with multiple comorbidities, including conditions that may require long-term oral anticoagulation (OAC) (eg, atrial fibrillation) and antiplatelet therapy (eg, coronary artery disease). After TAVR among patients without baseline indications for OAC, recent data suggest dual-antiplatelet therapy to be associated with an increased risk for bleeding events, particularly early postprocedure, compared with single-antiplatelet therapy with aspirin. Concerns surrounding the potential for thrombotic complications have raised the hypothesis of adjunctive use of OAC for patients with no baseline indications for anticoagulation. Although effective in modulating thrombus formation at the valve level, the bleeding hazard has shown to be unacceptably high, and the net benefit of combining antiplatelet and OAC therapy is unproven. For patients with indications for the use of long-term OAC, such as those with atrial fibrillation, the adjunctive use of antiplatelet therapy increases bleeding. Whether direct oral anticoagulant agents achieve better outcomes than vitamin K antagonists remains under investigation. Overall, single-antiplatelet therapy and OAC appear to be reasonable strategies in patients without and with indications for concurrent anticoagulation. The aim of the present review is to appraise the current published research and recommendations surrounding the management of antithrombotic therapy after TAVR, with perspectives on evolving paradigms and ongoing trials.     

Diagnostic Accuracy of [11C]PIB Positron Emission Tomography for Detection of Cardiac Amyloidosis

ObjectivesThis dual-site study evaluated the diagnostic accuracy of the method.BackgroundPittsburgh compound ([¹¹C]PIB) positron emission tomography (PIB-PET) has shown promise as a specific and noninvasive method for the diagnosis of cardiac amyloidosis (CA).MethodsThe study had 2 parts. In the initial study, 51 subjects were included, 36 patients with known CA and increased wall thickness (15 immunoglobulin light chain [AL] and 21 transthyretin [ATTR] amyloidosis) and 15 control patients (7 were nonamyloid hypertrophic and 8 healthy volunteers). Subjects underwent PIB-PET and echocardiography. Sensitivity and specificity of PIB-PET were established for 2 simple semiquantitative approaches, standardized uptake value ratio (SUVR) and retention index (RI). The second part of the study included 11 amyloidosis patients (5 AL and 6 hereditary ATTR) without increased wall thickness to which the optimal cutoff values of SUVR (>1.09) and RI (>0.037 min^-1) were applied prospectively.ResultsThe diagnostic accuracy of visual inspection of [¹¹C]PIB uptake was 100% in discriminating CA patients with increased wall thickness from controls. Semiquantitative [¹¹C]PIB uptake discriminated CA from controls with a 94% (95% confidence interval [CI]: 80% to 99%) sensitivity for both SUVR and RI and specificity of 93% (95% CI: 66% to 100%) for SUVR and 100% (95% CI: 75% to 100%) for RI. [¹¹C]PIB uptake was significantly higher in AL-CA than in ATTR-CA patients (p < 0.001) and discriminated AL-CA from controls with 100% (95% CI: 88% to 100%) accuracy for both the semiquantitative measures. In the prospective group without increased wall thickness, RI was elevated compared to controls (p = 0.001) and 5 of 11 subjects were evaluated as [¹¹C]PIB PET positive.ConclusionsIn a dual-center setting, [¹¹C]PIB PET was highly accurate in detecting cardiac involvement in the main amyloid subtypes, with 100% accuracy in AL amyloidosis. A proportion of amyloidosis patients without known cardiac involvement were [¹¹C]PIB PET positive, indicating that the method may detect early stages of CA.     

Relationship Between Hospital Surgical Aortic Valve Replacement Volume and Transcatheter Aortic Valve Replacement Outcomes

ObjectivesThe aim of this study was to examine whether hospital surgical aortic valve replacement (SAVR) volume was associated with corresponding transcatheter aortic valve replacement (TAVR) outcomes.BackgroundRecent studies have demonstrated a volume-outcome relationship for TAVR.MethodsIn total, 208,400 fee-for-service Medicare beneficiaries were analyzed for all aortic valve replacement procedures from 2012 to 2015. Claims for patients <65 years of age, concomitant coronary artery bypass grafting surgery, other heart valve procedures, or other major open heart procedures were excluded, as were secondary admissions for aortic valve replacement. Hospital SAVR volumes were stratified on the basis of mean annual SAVR procedures during the study period. The primary outcomes were 30-day and 1-year post-operative TAVR survival. Adjusted survival following TAVR was assessed using multivariate Cox regression.ResultsA total of 65,757 SAVR and 42,967 TAVR admissions were evaluated. Among TAVR procedures, 21.7% (n = 9,324) were performed at hospitals with <100 (group 1), 35.6% (n = 15,298) at centers with 100 to 199 (group 2), 22.9% (n = 9,828) at centers with 200 to 299 (group 3), and 19.8% (n = 8,517) at hospitals with ≥300 SAVR cases/year (group 4). Compared with group 4, 30-day TAVR mortality risk-adjusted odds ratios were 1.32 (95% confidence interval: 1.18 to 1.47) for group 1, 1.25 (95% confidence interval: 1.12 to 1.39) for group 2, and 1.08 (95% confidence interval: 0.82 to 1.25) for group 3. These adjusted survival differences in TAVR outcomes persisted at 1 year post-procedure.ConclusionsTotal hospital SAVR volume appears to be correlated with TAVR outcomes, with higher 30-day and 1-year mortality observed at low-volume centers. These data support the importance of a viable surgical program within the heart team, and the use of minimum SAVR hospital thresholds may be considered as an additional metric for TAVR performance.     

Transcatheter Aortic Valve Replacement in Low-Risk Patients With Symptomatic Severe Bicuspid Aortic Valve Stenosis

ObjectivesThe aim of this study was to evaluate clinical outcomes and transcatheter heart valve hemodynamic parameters after transcatheter aortic valve replacement (TAVR) in low-risk patients with bicuspid aortic stenosis (AS).BackgroundTAVR is approved for low-risk patients in the United States. However, patients with bicuspid AS were excluded from the randomized cohorts of the pivotal low-risk trials.MethodsThe LRT (Low Risk TAVR) trial was an investigator-initiated, prospective, multicenter study and was the first and only U.S. Food and Drug Administration–approved investigational device exemption trial to evaluate the feasibility of TAVR with either balloon-expandable or self-expanding valves in low-risk patients with bicuspid AS. The primary endpoint was all-cause mortality at 30 days. Baseline and follow-up echocardiography and computed tomography to detect leaflet thickening were analyzed in an independent core laboratory.ResultsSixty-one low-risk patients with symptomatic, severe AS and bicuspid aortic valves (78.3% Sievers type 1 morphology) underwent TAVR at 6 centers from 2016 to 2019. The mean age was 68.6 years, and 42.6% were men. At 30 days, there was zero mortality and no disabling strokes. The rate of new permanent pacemaker implantation was 13.1%; just 1 patient had a moderate paravalvular leak at 30 days. Hypoattenuated leaflet thickening was observed in 10% of patients at 30 days.ConclusionsTAVR appears to be safe in patients with bicuspid AS, with short length of hospital stay, zero mortality, and no disabling strokes at 30 days. Subclinical leaflet thrombosis was observed in a minority of patients at 30 days but did not appear to be associated with clinical events.     

18F-FDG-Based Radiomics and Machine Learning: Useful Help for Aortic Prosthetic Valve Infective Endocarditis Diagnosis?

BackgroundFluorine-18 fluorodeoxyglucose (¹⁸F-FDG)-positron emission tomography (PET)/computed tomography (CT) results in better sensitivity for prosthetic valve endocarditis (PVE) diagnosis, but visual image analysis results in relatively weak specificity and significant interobserver variability.ObjectivesThe primary objective of this study was to evaluate the performance of a radiomics and machine learning–based analysis of ¹⁸F-FDG PET/CT (PET-ML) as a major criterion for the European Society of Cardiology score using machine learning as a major imaging criterion (ESC-ML) in PVE diagnosis. The secondary objective was to assess performance of PET-ML as a standalone examination.MethodsAll ¹⁸F-FDG-PET/CT scans performed for suspected aortic PVE at a single center from 2015 to 2021 were retrospectively included. The gold standard was expert consensus after at least 3 months’ follow-up. The machine learning (ML) method consisted of manually segmenting each prosthetic valve, extracting 31 radiomics features from the segmented region, and training a ridge logistic regressor to predict PVE. Training and hyperparameter tuning were done with a cross-validation approach, followed by an evaluation on an independent test database.ResultsA total of 108 patients were included, regardless of myocardial uptake, and were divided into training (n = 68) and test (n = 40) cohorts. Considering the latter, PET-ML findings were positive for 13 of 22 definite PVE cases and 3 of 18 rejected PVE cases (59% sensitivity, 83% specificity), thus leading to an ESC-ML sensitivity of 72% and a specificity of 83%.ConclusionsThe use of ML for analyzing ¹⁸F-FDG-PET/CT images in PVE diagnosis was feasible and beneficial, particularly when ML was included in the ESC 2015 criteria. Despite some limitations and the need for future developments, this approach seems promising to optimize the role of ¹⁸F-FDG PET/CT in PVE diagnosis.     

Risk Assessment of Coronary Obstruction During Transcatheter Aortic Valve Replacement: Insights From Post-BASILICA Computed Tomography

ObjectivesThe aim of this study was to examine the predictive value of preprocedural computed tomography (CT)–based risk stratification of coronary obstruction during transcatheter aortic valve replacement (TAVR) on the basis of geometric measurements on postprocedural CT.BackgroundProper patient selection for additional procedures to prevent coronary obstruction during TAVR has not been adequately evaluated.MethodsPre- and postprocedural computed tomographic scans of 28 patients treated using bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction (BASILICA) and TAVR were analyzed. Using the postprocedural computed tomographic images, threatened coronary obstruction (TCO) was defined as: 1) ostial obstruction (adherence of the transcatheter heart valve [THV] to the coronary ostium with leaflet extension above the ostium); and/or 2) sinus sequestration (THV adherence to the sinotubular junction [STJ] with leaflet extension above the STJ) and was substratified into complete and incomplete types.ResultsA total of 51 leaflets were evaluated (88% surgical tissue valves) after excluding leaflets not visible on CT (n = 5). On postprocedural CT, complete TCO was observed in 25.4% (13 of 51 leaflets). On preprocedural CT, leaflets were at high risk for complete TCO (incidence 53%) if the virtual THV–to–coronary distance (VTC) was <3.0 mm, or if the virtual THV–to–STJ distance (VTSTJ) was <1.0 mm with STJ height ? leaflet length <0 mm (leaflet-STJ mismatch). Leaflets were at low risk (incidence 0%) if the VTC was ≥3 mm and VTSTJ was ≥3.0 mm or STJ height ? leaflet length was ≥+2.0 mm. Of 28 leaflets treated using BASILICA, complete TCO was seen in 35.7% (n = 10), due to sinus sequestration (100%) with coexisting ostial obstruction (30%). Actual coronary events occurred in 7.1% (n = 2) because of leaflet prolapse, corresponding to an absolute risk reduction by BASILICA of 29% (P = 0.021).ConclusionsRisk assessment of coronary obstruction after TAVR may improve with a multiparametric approach incorporating VTC, VTSTJ, and leaflet-STJ mismatch. BASILICA appeared to reduce actual coronary events even in leaflets with anticipated coronary obstruction.     

Transcatheter Aortic Valve-in-Valve Replacement for Degenerated Stentless Bioprosthetic Aortic Valves: Results of a Multicenter Retrospective Analysis

ObjectivesThe purpose of this study was to evaluate the safety and efficacy of valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) for stentless bioprosthetic aortic valves (SBAVs) and to identify predictors of adverse events.BackgroundViV TAVR in SBAVs is associated with unique technical challenges and risks.MethodsClinical records and computer tomographic scans were retrospectively reviewed for procedural complications, predictors of coronary obstruction, mortality, and echocardiographic results.ResultsAmong 66 SBAV patients undergoing ViV TAVR, mortality was 2 of 66 patients (3.0%) at 30 days and 5 of 52 patients (9.6%) at 1 year. At 1 year, left ventricular end-systolic dimension was decreased versus baseline (median [interquartile range (IQR)]: 3.0 [2.6 to 3.6] cm vs. 3.7 [3.2 to 4.4] cm; p < 0.001). Coronary occlusion in 6 of 66 procedures (9.1%) resulted in myocardial infarction in 2 of 66 procedures (3.0%). Predictors of coronary occlusion included subcoronary implant technique compared with full root replacement (6 of 31, 19.4% vs. 0 of 28, 0%; p = 0.01), short simulated radial valve-to-coronary distance (median [IQR]: 3.4 [0.0 to 4.6] mm vs. 4.6 [3.2 to 6.2] mm; p = 0.016), and low coronary height (7.8 [5.8 to 10.0] mm vs. 11.6 [8.7 to 13.9] mm; p = 0.003). Coronary arteries originated <10 mm above the valve leaflets in 34 of 97 unobstructed coronary arteries (35.1%).ConclusionsTAVR in SBAVs is frequently associated with high-risk coronary anatomy but can be performed with a low risk of death and myocardial infarction, resulting in favorable ventricular remodeling. A subcoronary surgical approach is associated with an increased risk of coronary obstruction.     

Transcatheter Versus Rapid-Deployment Aortic Valve Replacement: A Propensity-Matched Analysis From the German Aortic Valve Registry

ObjectivesThis study sought to compare patient characteristics, procedural outcomes, and valve hemodynamics of surgical aortic valve replacement (SAVR) with current-generation rapid-deployment valves (RDVs) versus transcatheter aortic valve replacement (TAVR) with current-generation transcatheter heart valves (THVs).BackgroundThe patient population currently treated with RDVs may have potential similarities with the current TAVR population, but comparative studies in a large patient population remain scarce.MethodsA total of 16,473 patients who underwent isolated SAVR using current-generation RDVs or isolated transfemoral TAVR with current-generation THVs between 2011 and 2017 were enrolled into the German Aortic Valve Registry. Baseline, procedural, and in-hospital outcome parameters were analyzed for RDVs and THVs before and after 1:1 propensity score matching. Furthermore, RDVs and THVs with similar design characteristics were compared with each other.ResultsA total of 1,743 patients received SAVR with an RDV, whereas 14,730 patients were treated with transfemoral TAVR. Patients treated with TAVR were significantly older and had higher surgical risk scores. Following valve replacement, patients treated with an RDV had a significantly higher rate of disabling stroke (1.7% vs. 1.1%; p = 0.03), need for transfusion of >4 red blood cell units (8.5% vs. 1.4%; p < 0.001), and new onset renal replacement therapy (1.9% vs. 1.2%; p = 0.01), whereas the need for a new permanent pacemaker was lower (8.4% vs. 14.9%; p < 0.001). In-hospital mortality was similar (1.6% vs. 1.8%; p = 0.62). These findings persisted after 1:1 propensity score matching, but in-hospital mortality was significantly higher after RDVs (1.7% vs. 0.6%; p = 0.003). Balloon-expandable (BE) RDVs had significantly lower residual gradients compared with BE-THVs, while self-expanding (SE)-RDVs had significantly higher residual gradients compared with SE-THVs.ConclusionsIn a large all-comers’ registry, TAVR with current-generation THVs was associated with improved in-hospital outcomes compared with SAVR with current-generation RDVs. The pacemaker rate is significantly higher with TAVR. Post-procedural hemodynamic function varied between individual RDVs and THVs.     

Long-Term Follow-Up of Hypoattenuated Leaflet Thickening After Transcatheter Aortic Valve Replacement

BackgroundEarly hypoattenuated leaflet thickening (HALT) occurs in at least 10% of all transcatheter aortic valve replacement (TAVR) patients. The long-term prognostic impact of HALT is uncertain.ObjectivesThe aim of this study was to assess the long-term risk of early HALT post-TAVR.MethodsWe report outcome data from our prospective observational registry with post-TAVR computed tomography angiography performed between May 2012 and December 2017. The outcomes were survival, cardiovascular mortality, ischemic cerebrovascular events, and symptomatic hemodynamic valve deterioration.ResultsEarly HALT was diagnosed in 115 (16.0%) of 804 patients. During a median follow-up of 3.25 years, survival rates did not differ significantly between patients with and without HALT (Kaplan-Meier 3-year estimates for survival 70.1% vs 74.0%, P = 0.597). The 3-year cardiovascular mortality rate was 13.2% versus 11.3% (with vs without HALT, P = 0.733). The 3-year event rate for cerebrovascular events was 2.0% versus 4.4% (with vs without HALT, P = 0.246), and the 3-year event rate of symptomatic hemodynamic valve deterioration was 9.4% versus 1.5% (with vs without HALT, P < 0.001). Multivariable analysis revealed the following predictors of symptomatic hemodynamic valve deterioration: HALT (HR: 6.10; 95% CI: 2.59-14.29; P < 0.001), the mixed valve–type group (HR: 6.51; 95% CI: 2.38-17.81; P < 0.001), and prosthesis diameter (HR valve size per 3 mm [HR: 0.37; 95% CI: 0.17-0.79]; P = 0.011).ConclusionsDuring a median follow-up of more than 3 years, HALT was not associated with mortality or cerebrovascular events. However, we observed an association of HALT with symptomatic hemodynamic valve deterioration.     

Wall Shear Stress Predicts Aortic Dilation in Patients With Bicuspid Aortic Valve

ObjectivesThis study sought to assess the predictive value of wall shear stress (WSS) for colocalized ascending aorta (AAo) growth rate (GR) in patients with bicuspid aortic valve (BAV).BackgroundBAV is associated with AAo dilation, but there is limited knowledge about possible predictors of aortic dilation in patients with BAV. An increased WSS has been related to aortic wall damage in patients with BAV, but no previous prospective study tested its predictive value for dilation rate. Recently, a registration-based technique for the semiautomatic mapping of aortic GR has been presented and validated.MethodsForty-seven patients with BAV free from valvular dysfunction prospectively underwent 4-dimensional flow cardiac magnetic resonance to compute WSS and subsequent follow-up with 2 electrocardiogram-gated high-resolution contrast-enhanced computed tomography angiograms for GR assessment.ResultsDuring a median follow-up duration of 43 months, mid AAo GR was 0.24 mm/year. WSS and its circumferential component showed statistically significant association with mid AAo GR in bivariate (P = 0.049 and P = 0.014, respectively) and in multivariate analysis corrected for stroke volume and either baseline AAo diameter (P = 0.046 and P = 0.014, respectively) or z-score (P = 0.036 and P = 0.012, respectively). GR mapping further detailed that GR was heterogeneous in the AAo and that circumferential WSS, but not WSS magnitude, showed statistically significant positive associations with GR in the regions with the fastest growth.Conclusions4D flow cardiac magnetic resonance–derived WSS and, in particular, its circumferential component predict progressive dilation of the ascending aorta in patients with BAV. Thus, the assessment of WSS may be considered in the follow-up of these patients.