Low-Flow, Low-Gradient, Normal Ejection Fraction Aortic Stenosis

A substantial proportion of patients with severe aortic stenosis may paradoxically have low transvalvular flow and a low gradient, despite the presence of normal left ventricular (LV) ejection fraction. These patients are characterized by pronounced LV concentric remodeling with small LV cavity size, impaired LV filling, altered myocardial function, and worse prognosis. This frequent clinical entity is often misdiagnosed, which may lead to an underestimation of aortic stenosis severity and thereby to underutilization or inappropriate delay of surgery. It is important to recognize this entity so we do not deny surgery to a symptomatic patient with small aortic valve area and low gradient. Thus, when there is a discordance between the valve area (in the severe range) and the gradient (in the moderate range) in patients with preserved LV ejection fraction, a more comprehensive Doppler echocardiographic evaluation and potentially other diagnostic tests may be required to confirm disease severity and guide therapeutic management.     

Workup and Management of Patients With Paradoxical Low-Flow,Low-Gradient Aortic Stenosis

About 60% of patients with paradoxical low-flow, low-gradient (PLF-LG) aortic stenosis (AS) have a severe disease that justifies aortic valve replacement (AVR). The first step in patients with symptomatic PLF AS should be to rule out measurement errors and treat hypertension. The second step is to distinguish pseudo-severe from true severe AS (TSAS). The third step is to select the optimal treatment modality at the right time. Regarding the second step, projected aortic valve area calculated using stress echocardiography is superior to traditional severity criteria (AVA <?1.0 cm² and mean gradient ≥?40 mmHg) to unmask TSAS and predict outcomes. Aortic valve calcification score quantitated by computed tomography is helpful to identify TSAS by applying thresholds of 2000 and 1200 AU, respectively, for men and women. This modality should be considered, particularly if stress echocardiography is either not feasible or inconclusive. Once AS severity is confirmed, a risk stratification based on symptomatic status and the importance of left ventricular (LV) systolic impairment will guide therapeutic decision. Symptomatic assessment should not solely rely on patient-reported symptom status, but rather include an objective exercise test. The presence of symptomatic PLF-LG TSAS is a class IIa indication for AVR in the guidelines. In asymptomatic patients, a markedly reduced stroke volume, the presence of myocardial fibrosis by cardiac magnetic resonance imaging, a poor longitudinal LV function as assessed by speckle tracking echocardiography, and/or a moderate to severe LV diastolic dysfunction are predictors of poor outcome in PLF-LG patients and may indicate the need of early AVR. The type of AVR should be discussed within a multidisciplinary team, bearing in mind that transcatheter AVR (TAVR) is superior to medical treatment in inoperable patients. Furthermore, TAVR may be a useful alternative to surgical AVR (SAVR) in high-risk patients. Nevertheless, the potential benefits of TAVR, including the lower risk of severe patient-prosthesis mismatch, should be weighed against the risk of paravalvular regurgitation, which is likely poorly tolerated by patients with PLF-LG who often harbor a small and non-compliant LV cavity.     

Natural Progression of Low-Gradient Severe Aortic Stenosis with Preserved Ejection Fraction

Because the natural progression of low-gradient aortic stenosis (LGAS) has not been well defined, we performed a retrospective study of 116 consecutive patients with aortic stenosis who had undergone follow-up echocardiography at a median interval of 698 days (range, 371–1,020 d). All patients had preserved left ventricular ejection fraction (>0.50) during and after follow-up.At baseline, patients were classified by aortic valve area (AVA) as having mild stenosis (≥1.5 cm²), moderate stenosis (≥1 to <1.5 cm²), or severe stenosis (<1 cm²). Severe aortic stenosis was further classified by mean gradient (LGAS, mean <40 mmHg; high-gradient aortic stenosis [HGAS], mean ≥40 mmHg). We compared baseline and follow-up values among 4 groups: patients with mild stenosis, moderate stenosis, LGAS, and HGAS.At baseline, 30 patients had mild stenosis, 54 had moderate stenosis, 24 had LGAS, and 8 had HGAS. Compared with the moderate group, the LGAS group had lower AVA but similar mean gradient. Yet the actuarial curves for progressing to HGAS were significantly different: 25% of patients in LGAS reached HGAS status significantly earlier than did 25% of patients in the moderate-AS group (713 vs 881 d; P=0.035).Because LGAS has a high propensity to progress to HGAS, we propose that low-gradient aortic stenosis patients be closely monitored as a distinct subgroup that warrants more frequent echocardiographic follow-up.     

Reduced Left Ventricular Ejection Fraction in Patients With Aortic Stenosis

Background

Left ventricular ejection fraction (LVEF) is reduced in a subset of patients with severe aortic stenosis (AS).

Prognostic Value of Computed Tomography–Derived Extracellular Volume in TAVR Patients With Low-Flow Low-Gradient Aortic Stenosis

ObjectivesThe association between extracellular volume (ECV) measured by computed tomography angiography (CTA) and clinical outcomes was evaluated in low-flow low-gradient (LFLG) aortic stenosis (AS) patients undergoing transcatheter aortic valve replacement (TAVR).BackgroundPatients with LFLG AS comprise a high-risk group with respect to clinical outcomes. Although ECV, a marker of myocardial fibrosis, is traditionally measured with cardiac magnetic resonance, it can also be measured using cardiac CTA. The authors hypothesized that in LFLG AS, increased ECV may be associated with adverse clinical outcomes.MethodsIn 150 LFLG patients with AS who underwent TAVR, ECV was quantified using pre-TAVR CTA. Echocardiographic and clinical information including all-cause death and heart failure rehospitalization (HFH) was obtained from electronic medical records. A Cox proportional hazards model was used to evaluate the association between ECV and death+HFH.ResultsDuring a median follow-up of 13.9 months (range 0.07 to 28.9 months), there were 31 death+HFH events (21%). Patients who experienced death+HFH had a greater median Society of Thoracic Surgery score (9.9 vs. 4.7; p < 0.01), lower left ventricular ejection fraction (42.3 ± 20.2% vs. 52.7 ± 17.2%; p < 0.01), lower mean transvalvular gradient (24.9 ± 8.9 mm Hg vs. 28.1 ± 7.3 mm Hg; p = 0.04) and increased mean ECV (35.5 ± 9.6% vs. 29.9 ± 8.2%; p < 0.01) compared with patients who did not experience death+HFH. In a multivariable Cox proportional hazards model, increase in ECV was associated with increase in death+HFH, (hazard ratio per 1% increase: 1.04, 95% confidence interval: 1.01 to 1.09; p < 0.01).ConclusionsIn patients with LFLG AS, CTA measured increase in ECV is associated with increased risk of adverse clinical outcomes post-TAVR and may thus serve as a useful noninvasive marker for prognostication.     

Clinical Outcomes and Revascularization Strategies in Patients With Low-Flow,Low-Gradient Severe Aortic Valve Stenosis According to the Assigned Treatment Modality

ObjectivesThis study compared clinical outcomes and revascularization strategies among patients presenting with low ejection fraction, low-gradient (LEF-LG) severe aortic stenosis (AS) according to the assigned treatment modality.BackgroundThe optimal treatment modality for patients with LEF-LG severe AS and concomitant coronary artery disease (CAD) requiring revascularization is unknown.MethodsOf 1,551 patients, 204 with LEF-LG severe AS (aortic valve area <1.0 cm², ejection fraction <50%, and mean gradient <40 mm Hg) were allocated to medical therapy (MT) (n = 44), surgical aortic valve replacement (SAVR) (n = 52), or transcatheter aortic valve replacement (TAVR) (n = 108). CAD complexity was assessed using the SYNTAX score (SS) in 187 of 204 patients (92%). The primary endpoint was mortality at 1 year.ResultsLEF-LG severe AS patients undergoing SAVR were more likely to undergo complete revascularization (17 of 52, 35%) compared with TAVR (8 of 108, 8%) and MT (0 of 44, 0%) patients (p < 0.001). Compared with MT, both SAVR (adjusted hazard ratio [adj HR]: 0.16; 95% confidence interval [CI]: 0.07 to 0.38; p < 0.001) and TAVR (adj HR: 0.30; 95% CI: 0.18 to 0.52; p < 0.001) improved survival at 1 year. In TAVR and SAVR patients, CAD severity was associated with higher rates of cardiovascular death (no CAD: 12.2% vs. low SS [0 to 22], 15.3% vs. high SS [>22], 31.5%; p = 0.037) at 1 year. Compared with no CAD/complete revascularization, TAVR and SAVR patients undergoing incomplete revascularization had significantly higher 1-year cardiovascular death rates (adj HR: 2.80; 95% CI: 1.07 to 7.36; p = 0.037).ConclusionsAmong LEF-LG severe AS patients, SAVR and TAVR improved survival compared with MT. CAD severity was associated with worse outcomes and incomplete revascularization predicted 1-year cardiovascular mortality among TAVR and SAVR patients.     

Tricuspid Regurgitation Is Associated With Increased Risk of Mortality in Patients With Low-Flow Low-Gradient Aortic Stenosis and Reduced Ejection Fraction: Results of the Multicenter TOPAS Study (True or Pseudo-Severe Aortic Stenosis)

ObjectivesThis study sought to examine the impact of tricuspid regurgitation (TR) on mortality in patients with low-flow, low-gradient (LF-LG) aortic stenosis (AS) and reduced left ventricular ejection fraction (LVEF).BackgroundTR is often observed in patients with LF-LG AS and low LVEF, but its impact on prognosis remains unknown.MethodsA total of 211 patients (73 ± 10 years of age; 77% men) with LF-LG AS (mean gradient <40 mm Hg and indexed aortic valve area [AVA] ≤0.6 cm²/m²) and reduced LVEF (≤40%) were prospectively enrolled in the TOPAS (True or Pseudo-Severe Aortic Stenosis) study and 125 (59%) of them underwent aortic valve replacement (AVR) within 3 months following inclusion. The severity of AS was assessed by the projected AVA (AVA_proj) at normal flow rate (250 ml/s), as previously described and validated. The severity of TR was graded according to current guidelines.ResultsAmong the 211 patients included in the study, 22 (10%) had no TR, 113 (54%) had mild (grade 1), 50 (24%) mild-to-moderate (grade 2), and 26 (12%) moderate-to-severe (grade 3) or severe (grade 4) TR. During a mean follow-up of 2.4 ± 2.2 years, 104 patients (49%) died. Univariable analysis showed that TR ≥2 was associated with increased risk of all-cause mortality (hazard ratio [HR]: 1.82, 95% confidence interval [CI]: 1.22 to 2.71; p = 0.004) and cardiovascular mortality (HR: 1.85, 95% CI: 1.20 to 2.83; p = 0.005). After adjustment for age, sex, coronary artery disease, AVA_proj, LVEF, stroke volume index, right ventricular dysfunction, mitral regurgitation, and type of treatment (AVR vs. conservative), the presence of TR ≥2 was an independent predictor of all-cause mortality (HR: 1.88, 95% CI: 1.08 to 3.23; p = 0.02) and cardiovascular mortality (HR: 1.92, 95% CI: 1.05 to 3.51; p = 0.03). Furthermore, in patients undergoing AVR, TR ≥3 was an independent predictor of 30-day mortality compared with TR = 0/1 (odds ratio [OR]: 7.24, 95% CI: 1.56 to 38.2; p = 0.01) and TR = 2 (OR: 4.70, 95% CI: 1.00 to 25.90; p = 0.05).ConclusionsIn patients with LF-LG AS and reduced LVEF, TR is independently associated with increased risk of cumulative all-cause mortality and cardiovascular mortality regardless of the type of treatment. In patients undergoing AVR, moderate/severe TR is associated with increased 30-day mortality. Further studies are needed to determine whether TR is a risk marker or a risk factor of mortality and whether concomitant surgical correction of TR at the time of AVR might improve outcomes for this high-risk population.     

Self-Expanding Transcatheter Aortic Valve Replacement in Patients With Low-Gradient Aortic Stenosis

Objectives

The authors sought to compare clinical and hemodynamic outcomes in patients receiving transcatheter aortic valve replacement (TAVR) for low-gradient (LG) aortic stenosis in the CoreValve EUS (Expanded Use Study) versus those with high-gradient (HG) aortic stenosis from the CoreValve U.S. Pivotal Extreme Risk Trial and CAS (Continued Access Study).

1-Year Survival After TAVR of Patients With Low-Flow,Low-Gradient and High-Gradient Aortic Valve Stenosis in Matched Study Populations

ObjectivesThis study sought to examine whether the prognosis of patients with severe aortic stenosis (AS) having high versus low transvalvular mean pressure gradients (MPGs) is intrinsically different after transcatheter aortic valve replacement (TAVR), even after strict matching of baseline parameters.BackgroundPatients with low MPG are characterized by higher cardiovascular risk and more comorbidities than other AS patients are.MethodsIn this retrospective, single-center study involving 2,282 patients, 3 groups were derived according to the following criteria: 1) high-gradient AS (HG-AS) (MPG ≥40 mm Hg); 2) low-flow, low-gradient AS (LFLG-AS) (MPG <40 mm Hg, ejection fraction [EF] ≤40%, stroke volume index ≤35 ml/m²); 3) paradoxical LFLG-AS (pLFLG-AS) (similar to LFLG-AS but with EF ≥50%). Propensity score matching that included EF was used to compare 1-year survival.ResultsA total of 136 patients with HG-AS or LFLG-AS were identified. Kaplan-Meier survival curves were significantly different (p = 0.039), with death occurring in 11 versus 21 patients (hazard ratio: 2.12; 95% confidence interval: 1.02 to 4.39; p = 0.044), respectively. A total of 226 patients with HG-AS or pLFLG-AS were identified and here the curves were identical (p = 0.468), with death occurring in 18 versus 21 patients (hazard ratio: 1.26; 95% confidence interval: 0.67 to 2.38; p = 0.469).ConclusionsThis is the first study comparing survival after TAVR of patients with high versus low MPG in matched study populations. Mortality in patients with LFLG-AS was twice that of HG-AS patients. However, it appears that patients with pLFLG-AS might benefit from TAVR to the same extent as patients with HG-AS. There must be still unmasked factors that influence mortality of patients with LFLG-AS.     

Decline in Left Ventricular Ejection Fraction During Follow-Up in Patients With Severe Aortic Stenosis

ObjectivesThe aim of this study was to investigate the prognostic impact of the decline in left ventricular ejection fraction (LVEF) at 1-year follow-up in patients with severe aortic stenosis (AS) managed conservatively.BackgroundNo previous study has explored the association between LVEF decline during follow-up and clinical outcomes in patients with severe AS.MethodsAmong 3,815 patients with severe AS enrolled in the multicenter CURRENT AS (Contemporary Outcomes After Surgery and Medical Treatment in Patients With Severe Aortic Stenosis) registry in Japan, 839 conservatively managed patients who underwent echocardiography at 1-year follow-up were analyzed. The primary outcome measure was a composite of AS-related deaths and hospitalization for heart failure.ResultsThere were 91 patients (10.8%) with >10% declines in LVEF and 748 patients (89.2%) without declines. Left ventricular dimensions and the prevalence of valve regurgitation and atrial fibrillation or flutter significantly increased in the group with declines in LVEF. The cumulative 3-year incidence of the primary outcome measure was significantly higher in the group with declines in LVEF than in the group with no decline (39.5% vs. 26.5%; p < 0.001). After adjusting for confounders, the excess risk of decline in LVEF over no decline for the primary outcome measure remained significant (hazard ratio: 1.98; 95% confidence interval: 1.29 to 3.06). When stratified by LVEF at index echocardiography (≥70%, 60% to 69%, and <60%), the risk of decline in LVEF on the primary outcome was consistently seen in all the subgroups, without any interaction (p = 0.77).ConclusionsPatients with severe AS with >10% declines in LVEF at 1 year after diagnosis had worse AS-related clinical outcomes than those without declines in LVEF under conservative management. (Contemporary Outcomes After Surgery and Medical Treatment in Patients With Severe Aortic Stenosis Registry; UMIN000012140)     

Low Transvalvular Flow Rate Predicts Mortality in Patients With Low-Gradient Aortic Stenosis Following Aortic Valve Intervention

ObjectivesThis study aimed to assess the value of low transvalvular flow rate (FR) for the prediction of mortality compared with low stroke volume index (SVi) in patients with low-gradient (mean gradient: <40 mm Hg), low aortic valve area (<1 cm²) aortic stenosis (AS) following aortic valve intervention.BackgroundTransaortic FR defined as stroke volume/left ventricular ejection time is also a marker of flow; however, no data exist comparing the relative prognostic value of these 2 transvalvular flow markers in patients with low-gradient AS who had undergone valve intervention.MethodsWe retrospectively followed prospectively assessed consecutive patients with low-gradient, low aortic valve area AS who underwent aortic valve intervention between 2010 and 2014 for all-cause mortality.ResultsOf the 218 patients with mean age 75 ± 12 years, 102 (46.8%) had low stroke volume index (SVi) (<35 ml/m²), 95 (43.6%) had low FR (<200 ml/s), and 58 (26.6%) had low left ventricular ejection fraction <50%. The concordance between FR and SVi was 78.8% (p < 0.005). Over a median follow-up of 46.8 ± 21 months, 52 (23.9%) deaths occurred. Patients with low FR had significantly worse outcome compared with those with normal FR (p < 0.005). In patients with low SVi, a low FR conferred a worse outcome than a normal FR (p = 0.005), but FR status did not discriminate outcome in patients with normal SVi. By contrast, SVi did not discriminate survival either in patients with normal or low FR. Low FR was an independent predictor of mortality (p = 0.013) after adjusting for age, clinical prognostic factors, European System for Cardiac Operative Risk Evaluation II, dimensionless velocity index, left ventricular mass index, left ventricular ejection fraction, heart rate, time, type of aortic valve intervention, and SVi (p = 0.59).ConclusionsIn patients with low-gradient, low valve area aortic stenosis undergoing aortic valve intervention, low FR, not low SVi, was an independent predictor of medium-term mortality.     

Comparison of Beta-Blocker Effectiveness in Heart Failure Patients With Preserved Ejection Fraction Versus Those With Reduced Ejection Fraction

BackgroundThe aim of this study was to compare the benefit of beta-blockers (BB) in heart failure (HF) with preserved versus reduced ejection fraction (EF).Methods and ResultsThis was a retrospective study of insured patients who were hospitalized for HF from January 2000 to June 2008. Pharmacy claims were used to estimate BB exposure over 6-month rolling windows. The association between BB exposure and all-cause hospitalization or death was tested with the use of time-updated proportional hazards regression, with adjustment for baseline covariates and other HF medication exposure. The groups were compared by stratification (EF <50% vs ≥50%) and with the use of an EF-group × BB exposure interaction term. A total of 1,835 patients met the inclusion criteria, 741 (40%) with a preserved EF. Median follow-up was 2.1 years. In a fully adjusted multivariable model, BB exposure was associated with a decreased risk of death or hospitalization in both groups (EF <50%: hazard ratio [HR] 0.53 [P < .0001]; EF ≥50%: HR 0.68 [P = .009]). There was no significant difference in this protective association between groups (interaction: P = .32).ConclusionsBB exposure was associated with a similar protective effect regarding time to death or hospitalization in HF patients regardless of whether EF was preserved or reduced. An adequately powered randomized trial of BB in HF with preserved EF is warranted.