Left anterior descending coronary artery flow impaired by right ventricular apical pacing: The role of systolic dyssynchrony

Introduction

Right ventricular (RV) pacing may affect myocardial perfusion and coronary blood flow; however, it remains unknown whether this is related to systolic dyssynchrony induced by RV pacing. This prospective study was aimed to assess the relationship between dyssynchrony and the changes of coronary blood flow.

Methods

Seventy patients with sinus node dysfunction were prospectively enrolled. Coronary flow was evaluated by measuring diastolic velocity time integral (VTI) and duration at the distal-portion of left anterior descending coronary artery (LAD) with transthoracic echocardiography at baseline and follow-up. Systolic dyssynchrony was assessed with tissue Doppler imaging by time standard deviation to peak systolic velocity of 12 left ventricular segments (Ts-SD, cutoff value ≥ 33 ms).

Results

Adequate data for analysis was available from 65 patients. At follow-up (mean follow up time: 127 ± 45 days), LAD velocity-time integral (LAD-VTI: 12.1 ± 4.2 vs. 10.7 ± 4.6 cm, p < 0.001) was decreased and there was deterioration of left ventricular systolic function (left ventricular ejection fraction: 65 ± 7% vs. 62 ± 7%). However, these changes were only detected in those with RV pacing induced systolic dyssynchrony. Significant reduction of LAD-VTI (defined as ≥ 5%) occurred in 34 (52%) patients which was more prevalent in those with pacing-induced systolic dyssynchrony than those without (85.3% versus 16.1%, χ² = 31.1, p < 0.001). Though similar at baseline, LAD-VTI was significantly lower in the dyssynchrony group at follow up (p < 0.001). Cox-regression analysis showed that pacing-inducing systolic dyssynchrony [hazard ratio (HR): 3.62, p = 0.009] and higher accumulative pacing percentage (HR: 1.02, p = 0.002) were independently associated with reduction of LAD-VTI. ROC curve demonstrated that accumulative pacing percentage ≥ 35% was 97% sensitive and 84% specific in revealing significant reduction (area under the curve: 0.961, p < 0.001).

Conclusions

RV pacing induced dyssynchrony is associated with reduced coronary flow and this may account for, in part, the deleterious effect of RV pacing on ventricular function over time.     

Early pacing-induced systolic dyssynchrony is a strong predictor of left ventricular adverse remodeling: Analysis from the Pacing to Avoid Cardiac Enlargement (PACE) trial

Background

Right ventricular apical (RVA) pacing is associated with adverse left ventricular (LV) remodeling and biventricular (BiV) pacing may prevent it although the mechanisms remain unclear. The current study aimed to assess the role of early pacing-induced systolic dyssynchrony (DYS) to predict adverse LV remodeling.

Methods

Patients with standard pacing indications and normal LV ejection fraction were randomized either to BiV (n = 89) or RVA pacing (n = 88). Pacing-induced DYS, defined as the standard deviation of the time to peak systolic velocity (Dyssynchrony Index) > 33 ms in a 12-segmental model of LV, was measured by tissue Doppler echocardiography at 1 month.

Results

At 1 month, 59 patients (33%) had DYS which was more prevalent in RVA than BiV pacing group (52% vs. 15%, χ² = 28.3, p < 0.001), though Dyssynchrony Index was similar at baseline (30 ± 14 vs. 26 ± 11 ms, p = 0.06). At 12 months, those developing DYS had significantly lower LV ejection fraction (55.1 ± 9.7 vs. 62.2 ± 7.9%, p < 0.001) and larger LV end-systolic volume (35.3 ± 14.3 vs. 27.0 ± 10.4 ml, p < 0.001) when compared to those without DYS. Reduction of ejection fraction ≥ 5% occurred in 67% (39 out of 58) of patients with DYS, but only in 18% (21 out of 115) in those without DYS (χ² = 40.8, p < 0.001). Both DYS at 1 month (odds ratio [OR]: 4.725, p = 0.001) and RVA pacing (OR: 3.427, p = 0.009) were independent predictors for reduction of ejection fraction at 12 months.

Conclusion

Early pacing-induced DYS is a significant predictor of LV adverse remodeling and the observed benefit of BiV pacing may be related to the prevention of DYS.

Clinical trial registration

Centre for Clinical Trials number, CUHK_CCT00037 (URL: http://www.cct.cuhk.edu.hk/Registry/publictrialrecord.aspx?trialid=CUHK_CCT00037).     

Estimation of infarct size using transthoracic Doppler echocardiographic measurement of coronary flow reserve in infarct related and reference coronary artery

Background

Patients in chronic phase of myocardial infarction (MI) have decreased coronary flow reserve (CFR) in infarct related artery (IRA) that is proportional to the extent of microvascular/myocardial damage. We proposed a novel model for the assessment of microvascular damage and infarct size using Doppler echocardiography evaluation of CFRs of the IRA (LAD) and reference artery (RCA).

Methods

Our study included 34 consecutive patients (28 men, mean age 50 ± 11 years) with first anterior STEMI and single vessel disease successfully treated with primary PCI. All patients underwent SPECT MPI for the assessment of infarct size (expressed as a percentage of myocardium with fixed perfusion abnormalities) and CFR evaluation of LAD and RCA. CFR derived percentage of microvascular damage (CFR PMD) was calculated as: CFR PMD = (CFR RCA − CFR LAD) / (CFR RCA − 1) × 100 (%).

Results

CFR PMD correlated significantly with all parameters evaluating the severity of myocardial damage including: peak CK activity (r = 0.632, p < 0.001), WMSI (r = 0.857, p < 0.001), ejection fraction (r = − 0.820, p < 0.001), left ventricular end diastolic (r = 0.757, p < 0.001) and end systolic volume (r = 0.794, p < 0.001). Most importantly, CFR PMD (22 ± 17%) correlated significantly with infarct size by SPECT MPI (21 ± 17%) (r = 0.874, p < 0.001).

Conclusions

CFR PMD derived from the proposed model was significantly related to echocardiographic and enzymatic parameters of infarct size, as well as to myocardial damage assessed by SPECT MPI in patients with successfully reperfused first anterior STEMI.     

Coronary microvascular dysfunction after elective percutaneous coronary intervention: Correlation with exercise stress test results

Objectives

We assessed whether exercise stress test (EST) results are related to the presence of coronary microvascular dysfunction (CMVD) in patients undergoing elective percutaneous coronary intervention (PCI).

Background

Previous studies showed that EST is poorly reliable in predicting restenosis after PCI; some studies also showed CMVD in the territory of the treated vessel.

Methods

We studied 29 patients (age 64 ± 6, 23 M) with stable coronary artery disease and isolated stenosis (> 75%) of the left anterior descending (LAD) coronary artery, undergoing successful PCI with stent implantation. EST and assessment of coronary microvascular function were performed 24 h, 3 months and 6 months after PCI. Coronary blood flow (CBF) response to adenosine and to cold-pressor test (CPT) was assessed in the LAD coronary artery by transthoracic Doppler echocardiography.

Results

Patients with ST-segment depression ≥ 1 mm at EST performed 24 h after PCI (n = 11, 38%) showed a lower CBF response to adenosine compared to those with negative EST (1.65 ± 0.4 vs. 2.11 ± 0.4, respectively, p = 0.003), whereas the difference in CBF response to CPT was not significant (1.44 ± 0.4 vs. 1.64 ± 0.3, respectively; p = 0.11). At 3-month and 6-month follow-up a positive EST was found in 12 (41%) and 13 (44%) patients, respectively; patients with positive EST also had lower CBF response to adenosine compared to those with negative EST (3 months: 1.69 ± 0.3 vs. 2.20 ± 0.3, respectively; 6 months: 1.66 ± 0.2 vs. 2.32 ± 0.3, respectively; p < 0.001 for both).

Conclusions

Positive EST after elective successful PCI consistently reflects impairment of hyperemic CBF due to CMVD, which persists over a follow-up period of 6 months.     

A reduction in total isovolumic time with cardiac resynchronisation therapy is a predictor of clinical outcomes

Background

Total isovolumic time (t-IVT) reflects left ventricular (LV) asynchrony (when the ventricle is neither ejecting nor filling). It is prolonged in left bundle branch block (LBBB). Cardiac resynchronisation therapy (CRT) is a treatment for patients with heart failure, reduced LV ejection fraction and LBBB. CRT shortens t-IVT, but the long-term clinical benefit of such reduction after CRT has not been studied in this patient group.

Methods

Seventy-three patients who underwent CRT had t-IVT measured before and after CRT implantation. The study end-point was a composite of unplanned heart failure hospitalisation and all-cause mortality.

Results

Baseline t-IVT showed considerable scatter: 30 patients had t-IVT values longer than 15 s/min (upper 95% limit of normal). The change in t-IVT with CRT was also variable: t-IVT shortened in 50 patients (from 16.2 ± 4.8 s/min to 11.7 ± 3.7 s/min: group A), and lengthened in 23 patients (from 11.7 ± 4.2 s/min to 14.5 ± 4.33 s/min: group B). The magnitude of change in t-IVT with CRT negatively correlated with baseline t-IVT (r = − 0.619, p < 0.001); thus t-IVT (significantly longer in group A than group B before CRT: 16.2 ± 4.8 s/min vs. 11.7 ± 4.2 s/min, p < 0.001) became significantly shorter in group A compared to group B after CRT (11.7 ± 3.7 s/min vs. 14.5 ± 4.3 s/min, p = 0.005). After follow-up of 30 months, 70% group A patients had event-free survival compared to 39% group B patients. The presence of any fall in t-IVT after CRT was an independent predictor of event-free survival.

Conclusion

T-IVT is a marker of global cardiac asynchrony that has predictive capacity on functional, symptomatic, and mortality endpoints in patients with advanced heart failure.     

Coronary flow dynamics in children after repair of Tetralogy of Fallot

Objectives

To assess the possible effect of a stiff right ventricle on the coronary flow (CF) in patients with post-operative Tetralogy of Fallot (TOF).

Background

Right ventricular restrictive physiology i.e. forward flow during atrial contraction (RVRP), is characteristic to many patients with post-operative TOF.

Methods

A total of 34 patients with TOF anatomically corrected through transatrial repair were included. Coronary flow parameters were registered with transthoracic Doppler echocardiography from posterior descending (PDCA) and left anterior descending (LAD) coronary arteries in the same patient in 24/34 (71%) patients. Twenty age-matched healthy children were used as controls. Cardiac magnetic resonance (CMR) imaging was used to detect myocardial fibrosis, RV volume, and RVRP.

Results

The mean age at investigation was 10.2 ± 2.8 years. RV end diastolic and end systolic volumes indexed for BSA were larger in patients with RVRP (p = 0.002 and 0.008 respectively). Peak flow velocity in diastole and flow velocity time integral was increased in patients compared to controls. They were increased in the LAD in patients with fibrosis of RV (n = 11) compared to patients without fibrosis (n = 9) (p = 0.01 and 0.047 respectively). LAD coronary flow was especially increased in patients with RVRP (n = 9) as compared with those without (n = 11), (p = 0.006).

Conclusions

Patients at mid-term followup after correction of TOF show increase of coronary flow. This increase is more pronounced in patients with fibrosis and RVRP of the RV.     

Relationship between whole-body macronutrient oxidative partitioning and pancreatic insulin secretion/β-cell function in non-diabetic humans

Background

Glucose-stimulated insulin secretion correlates inversely with the degree of whole-body insulin sensitivity suggesting a crosstalk between peripheral organs and pancreas. Such sensing mechanism could be mediated by changes in glucose flux (uptake, oxidation or storage) in peripheral tissues that may drive insulin secretion.

Aim

To relate whole-body non-protein respiratory quotient (npRQ), an index of macronutrient oxidative partitioning, with insulin secretion and β-cell function in non-diabetic individuals.

Methods

Macronutrient oxidation was measured after an overnight fast and for 4 h after a 75-g oral glucose tolerance test (OGTT) in 30 participants (15/15 males/females; 35 ± 12 y; 27 ± 4 kg/m²). Furthermore, npRQ was assessed for 24 h in a metabolic chamber. Insulin secretion was estimated by deconvolution of serum C-peptide concentration (fasting and 4-h OGTT) and from 24-h urinary C-peptide excretion corrected for energy intake (metabolic chamber). β-Cell function parameters were obtained by mathematical modeling, while insulin sensitivity was determined by a euglycemic–hyperinsulinemic clamp (120 mU · m^− 2 · min^− 1).

Results

Insulin secretion (from 24-h urinary C-peptide) correlated inversely with 24-h npRQ (r = − 0.61; p = 0.001), even after controlling for insulin sensitivity, energy balance, age and body mass index (r = − 0.52; p = 0.01). In turn, insulin secretion (from serum C-peptide) was not associated with fasting or OGTT npRQ. However, fasting npRQ was positively correlated with rate sensitivity (r = 0.40; p < 0.05) and marginally with glucose sensitivity (r = 0.34; p = 0.08).

Conclusion

Macronutrient oxidative partitioning, specifically glucose oxidation, might play a role on the regulation of insulin secretion. Further studies should aim at identifying the signals linking these processes.     

Impaired cardiac reserve in asymptomatic patients with moderate pulmonary restenosis late after relief of severe pulmonary stenosis: Evidence for diastolic dysfunction

Background

Patients with moderate pulmonary valve restenosis late after relief of severe pulmonary stenosis (PS) may show decreased exercise tolerance. To elucidate the mechanism of decreased exercise tolerance, we evaluated cardiac response to physical and pharmacological stress in these patients and compared results with those of patients with native moderate PS.

Methods

Twenty asymptomatic patients with moderate PS were divided into 2 groups: Group I (late after relief of severe PS, n = 9), and Group II (no previous intervention, n = 11). All patients underwent an exercise test, dobutamine stress (DS) MRI, and delayed contrast enhanced MRI. The response to physical and pharmacological stress was compared between both groups.

Results

Group I showed impaired exercise capacity compared to Group II (VO₂max = 72.8% ± 3.5% vs. 102.5% ± 16.3%, p < 0.001). During DS-MRI, RV-SV increased in Group II, but not in Group I (+ 13 ± 8 ml, − 5 ± 8 ml, p < 0.001). RV end‐diastolic volume decreased significantly in Group I patients (p = 0.006) while it did not significantly change in Group II patients. The amount of RV-SV increase (? RV-SV) correlated negatively with the period of moderate PS existence and the current PG in Group I (r = − 0.82, p = 0.007, and r = − 0.68, p = 0.04, respectively) but not in Group II (r = 0.45, p = 0.1, and r = 0.40, p = 0.2, respectively). Furthermore, ? RV-SV correlated negatively with the PG before valvuloplasty (r = − 0.76, p = 0.02).

Conclusion

Impaired exercise capacity in patients with moderate pulmonary restenosis after relief of severe PS is probably caused by inability to increase RV-SV. Disturbed RV filling properties, worsening in time, might play a role.     

Comparison of acute changes in left ventricular volume,systolic and diastolic functions,and intraventricular synchronicity after biventricular and right ventricular pacing for heart failure

Background

Biventricular pacing (BiV) therapy has recently been shown to improve systolic function and cause reverse remodeling in patients with advanced heart failure with electromechanical delay. In these patients, the benefit of right ventricular (RV)-based pacing was controversial. We compared the acute changes in systolic and diastolic function, left ventricular (LV) volume, and intraventricular synchronicity in BiV pacing, RV pacing, and without pacing (No) by means of echocardiography and tissue Doppler imaging (TDI).

Methods

TDI was performed in 33 patients with heart failure after undergoing pacemaker implantation, when the device was randomized to BiV, RV, and no pacing modes.

Results

Systolic function was only improved during BiV pacing, but not during RV pacing. This included ejection fraction (No vs RV vs BiV = 24% ± 12% vs 25% ± 10% vs 30% ± 14%, P = .02 vs No), +dp/dt (P = .01), myocardial performance index (P = .01), and isovolumic contraction time (P = .03). Mitral regurgitation was only reduced during BiV pacing (P = .02). LV early diastolic function was depressed in both RV and BiV pacing, as detected by transmitral flow (97 ± 34 vs 80 ± 34 vs 82 ± 32 cm/s, both P ≤ .005) and TDI (mean myocardial early diastolic velocity of 6 basal segments, 3.3 ± 1.7 vs 2.6 ± 1.0 vs 2.6 ± 1.0 cm/s, both P = .01). The LV end-diastolic (187 ± 86 vs 177 ± 84 vs 166 ± 79, P = .003) and end-systolic (146 ± 77 vs 138 ± 79 vs 122 ± 69, P = .003) volumes were only decreased during BiV pacing. For systolic synchronicity, a significant delay in peak systolic contraction in the lateral over the septal wall (171 ± 37 vs 217 ± 46 ms, P = .004) was revealed by TDI when there was no pacing. This was abolished by BiV pacing, in which septal contraction was delayed (195 ± 38 vs 201 ± 53 ms, P = not significant). However, RV pacing restored the lateral wall delay, and systolic asynchrony reappeared (190 ± 40 vs 227 ± 56 ms, P = .01). Diastolic asynchrony between the septal and lateral walls was not evident in these patients and was not affected by either pacing mode.

Conclusion

Only BiV pacing, but not RV pacing, improves systolic function, and reduces mitral regurgitation and LV volumes in patients with heart failure and electromechanical delay. This is attributed to the improvement of systolic synchronicity. Diastolic synchronicity was unaffected, whereas early diastolic function could be jeopardized, by either pacing mode.     

Don't move during ablation of atrial fibrillation!

Background

Restless patient is recalcitrant during ablation of atrial fibrillation (AF). We aimed to assess the association between patient movements during AF ablation and its outcome.

Methods

We examined the body movement during AF ablation in 78 patients with the use of a novel portable respiratory monitor, the SD-101, which also has the ability to quantify the frequency of body movements.

Results

The body movement index, defined as the number of the units of time with body movement events divided by the recording time (11.4 ± 6.5 events/h), was significantly correlated with the ablation time defined as the time from the first point of the ablation to the end of the procedure (1.2 ± 0.3 h) (r = 0.35; p = 0.0014) and a total radiofrequency energy applied (56.6 ± 17.7 kW) (r = 0.36; p = 0.0015). A multiple linear regression analysis showed that non-paroxysmal AF (β = 0.25; p = 0.036) and the body movement index (β = 0.36; p = 0.0019) were independent determinants of the ablation time. The body movement index was similar in patients with and without recurrence of AF.

Conclusions

Keeping patients motionless may be important to reduce the procedural duration of AF ablation.     

Impaired left ventricular systolic function reserve limits cardiac output and exercise capacity in HFpEF patients due to systemic hypertension

Objectives

Heart failure (HF) patients with preserved left ventricular (LV) ejection fraction (EF) (HFpEF) due to systemic hypertension (SHT) are known to have limited exercise tolerance. Despite having normal EF at rest, we hypothesize that these patients have abnormal systolic function reserve limiting their exercise capacity.

Methods

Seventeen patients with SHT (mean age 68 ± 9 years) but no valve disease and 14 healthy individuals (mean age of 65 ± 10 years) underwent resting and peak exercise echocardiography using conventional, tissue Doppler and speckle tracking techniques. The differences between resting and peak exercise values were also analyzed (Δ). Exercise capacity was determined as the workload divided by body surface area.

Results

Resting values for left atrial (LA) volume/BSA (r = − 0.66, p < 0.001) and global longitudinal strain rate (GLSR) in early (e) and late (a) diastole (r = 0.47 and 0.46, p < 0.05 for both) correlated with exercise capacity. LVEF increased during exercise in normals (mean Δ EF = 10 ± 8%) but failed to do so in patients (mean Δ EF = 0.6 ± 9%, p < 0.001 between groups). LV GLSR during systole (s) also failed to increase with exercise in patients, to the same extent as it did in normals (0.2 ± 0.2 vs. 0.6 ± 0.3 1/s, p < 0.001). The difference between rest and exercise (Δ) in LV lateral wall systolic velocity from tissue Doppler (s′) (0.71, p < 0.001), Δ in cardiac output (r = 0.60, p < 0.001) and Δ GLSRs (r = 0.48, p < 0.05) all correlated with exercise capacity independent of changes in heart rate.

Conclusion

HFpEF patients with hypertensive LV disease have significantly limited exercise capacity which is related to left atrial enlargement as well as compromised LV systolic function at the time of the symptoms. The limited myocardial systolic function reserve seems to be underlying important explanation for their limited exercise capacity.     

Pro B-type natriuretic peptide plasma value: A new criterion for the prediction of short- and long-term outcomes after transcatheter aortic valve implantation

Background

To determine the prognostic value of pro B-type natriuretic peptide (pro-BNP) to predict mortality after transcatheter aortic valve implantation (TAVI). Logistic EuroSCORE (LES) overestimates observed mortality after TAVI. A new risk score specific to TAVI is needed to accurately assess mortality and outcome.

Methods

Eighty-five patients were included. Indications for TAVI were nonoperable or surgically high-risk patients (LES > 20%). Pro-BNP was measured 24 h before the procedure. Cox proportional hazards model was used to evaluate clinical factors. The predictive accuracy of these Cox models was determined by using time-dependent receiver operating characteristic (ROC) curves.

Results

Pro-BNP levels (log-transformed) were significantly higher in non-survivors than in survivors at 30 days (3.36 ± 0.43 vs. 3.81 ± 0.43, p < 0.004) and at the end of follow-up (3.34 ± 0.42 vs. 3.63 ± 0.48, p < 0.011). Multivariate analysis revealed that only increased log pro-BNP levels were associated with higher mortality rate at short [hazard ratio (HR) (95% confidence intervals (CI)] = 5.35 (1.74–16.5), p = 0.003] and long-term follow-ups [HR = 11 (CI: 1.51–81.3), p = 0.018]. LES was not associated with increased mortality at either time point [HR = 1.03 (CI: 0.95–1.10), p = 0.483 and HR = 1.03 (CI: 0.98–1.07), p = 0.230, respectively]. At 30, 90, 180, and 365 days, the c-index was 0.72 for log pro-BNP and 0.63 for LES (p = 0.044).

Conclusion

Pre-procedure log transform of plasma pro-BNP levels are an independent and strong predictor of short- and long-term outcomes after TAVI and are more discriminatory than LES.     

Determinants and clinical significance of flow via the fenestration in the Fontan pathway: A multimodality study

Background

The use of a fenestration in the Fontan pathway remains controversial, partly because its hemodynamic effects and clinical consequences are insufficiently understood. The objective of this study was to quantify the magnitude of fenestration flow and to characterize its hemodynamic consequences after an intermediate interval after surgery.

Methods

Twenty three patients with a fenestrated extracardiac conduit prospectively underwent investigation by cardiac magnetic resonance (CMR), echocardiography, and invasive manometry under the same general anesthetic 12 ± 4 months after Fontan surgery. Fenestration flow was determined using phase contrast CMR by subtracting flow in the Fontan pathway above the fenestration from Fontan flow below the fenestration.

Results

Fenestration flow constituted a mean of 31 ± 12% (range 8–50%) of ventricular preload. It was associated with a lower Qp/Qs (r = − 0.64, p = 0.001) and oxygen saturation (r = − 0.74, p < 0.0001). Fenestration flow volume was correlated with pulmonary vascular resistance (r = 0.45, p = 0.04) and markers of ventricular diastolic function (early diastolic strain rate r = 0.57, p = 0.008 and ventricular untwist rate r = 0.54, p = 0.02).In 14 patients (61%) all of the net inferior vena cava flow and part of the superior vena cava flow were diverted into the systemic atrium and did not reach the lungs.

Conclusions

Fenestration flow can be measured accurately with CMR. In two-thirds of the patients not only all of the inferior vena cava flow, but also some of the superior vena cava flow is diverted through the fenestration. Fenestration flow is driven by a balance between pulmonary vascular resistance and early diastolic ventricular function.     

Relationship between fractional flow reserve and residual plaque volume and clinical outcomes after optimal drug-eluting stent implantation: Insight from intravascular ultrasound volumetric analysis

Background

The underlying cause of FFR reduction and prognostic impact of FFR after optimal DES implantation remain unknown. The study aims were to use intravascular ultrasound (IVUS) to investigate the mechanism responsible for reduced fractional flow reserve (FFR) after optimal drug-eluting stent (DES) implantation and to evaluate FFR effect on clinical outcomes after optimal percutaneous coronary intervention with DES.

Methods

Ninety-seven patients treated with optimal DES implantation under IVUS and pullback FFR guidance were followed clinically (median 17.8 months). Post-stenting IVUS examination and pullback FFR recording were performed, and angiographic and IVUS parameters associated with reduced FFR were evaluated. The composite of major adverse cardiac events (MACE), including cardiac death, myocardial infarction, stent thrombosis, and target vessel revascularization, was analyzed.

Results

Regression analysis showed inverse correlations between post-stent FFR and residual plaque volume index (r = − 0.40, p < 0.01) and residual percent plaque volume (r = − 0.68, p < 0.01) in IVUS but no correlation of minimal lesion diameter with quantitative coronary angiography (r = 0.07, p = 0.50) or IVUS-derived minimal stent area (r = 0.02, p = 0.84). MACE was observed in 10 patients (10.3%), and FFR after optimal stenting was significantly lower in this group (0.86 ± 0.04 vs 0.91 ± 0.04, p < 0.01). The optimal FFR threshold for predicting MACE was 0.90, identified by the receiver operating characteristic curve.

Conclusions

Reduced FFR after optimal DES implantation was associated with residual plaque volume identified by IVUS and future adverse cardiac events.     

Evaluación de la musculatura respiratoria en la predicción del resultado de la extubación de pacientes con ictus

Background

Patients with cerebral infarction often present impaired consciousness and unsatisfactory extubation. We aimed to assess the respiratory mechanics components that might be associated with the success of extubation in stroke patients.

Methods

Twenty consecutive patients with stroke who needed mechanical ventilation support were enrolled. The maximal inspiratory pressure, gastric and the esophageal pressure (Pdi/Pdimax), minute volume, respiratory rate, static compliance, airway resistance, rapid and superficial respiration index (RSRI), inspiratory time/total respiratory cycle (Ti/Ttot), and PaO₂/FiO₂ were measured.

Results

The group who presented success to the extubation process presented 12.5 ± 2.2 = days in mechan-ical ventilation and the group who failed presented 13.1 ± 2 = days. The mean Ti/Ttot and Pdi/Pdimax for the failure group was 0.4 ± 0.08 (0.36-0.44) and 0.5 ± 0.7 (0.43-0.56), respectively. The Ti/Ttot ratio was 0.37 ± 0.05 (0.34-0.41; p = 0.0008) and the Pdi/Pdimax was 0.25 ± 0.05 for the success group (0.21-0.28; p < 0.0001). A correlation was found between Pdi/Pdimax ratio and the RSRI (r = 0.55; p = 0.009) and PaO₂/FiO₂ (r = −0.59; p = 0.005). Patients who presented a high RSRI (OR, 3.66; p = 0.004) and Pdi (OR, 7.3; p = 0.002), and low PaO₂/FIO₂ (OR, 4.09; p = 0.007), Pdi/Pdimax (OR, 4.12; p = 0.002) and RAW (OR, 3.0; p = 0.02) developed mechanical ventilation extubation failure.

Conclusion

Muscular fatigue index is an important predicting variable to the extubation process in prolonged mechanical ventilation of stroke patients.     

The shape and function of the left ventricle in Ebstein's anomaly

Background

Left ventricular (LV) failure is common in Ebstein's anomaly, though remains poorly understood. We investigated whether shape deformity impacts LV function.

Methods

Three-dimensional models of the right ventricle (RV) and LV from 29 adult Ebstein's patients and nine normal subjects were generated from cardiac magnetic resonance image tracings. LV end diastolic (ED) shape, systolic function, septal motion and ventricular interaction were analyzed.

Results

LV ED volume index was normal in Ebstein's (75 ± 19 vs. 78 ± 11 ml/m² in normals, p = 0.50) but the LV was basally narrowed and modestly dilated apically. LV function was reduced globally (ejection fraction (EF) 41 ± 7 vs. 57 ± 5% in normals, p < 0.0001) and regionally (decreased mean segment displacement at end systole (ES) in 12/16 segments, basal Z-scores − 2.1 to − 1.0). Septal dyskinesis was suggested by outward mean segment displacement in at least one basal septal segment in 25 patients (86%) but refuted by septal thickening in 14 (48%), normal septal curvature at ED and ES, and by visually evident basal LV anterior translation in 27 patients (93%). LV EF correlated better with normalized tricuspid annular plane systolic excursion (r = 0.70) than with RV EF (r = 0.42) or RVEDVI (r = 0.18).

Conclusions

Although the Ebstein's LV has preserved volume, it exhibits basal narrowing, modest apical dilation and global hypokinesis. The apparent basal septal dyskinesis observed in most patients is likely attributable to anterior cardiac translation rather than true paradoxical motion. LV EF is unaffected by RV volume, correlating well instead with RV longitudinal shortening.     

Maintenance of sinus rhythm after electrical cardioversion for recurrent atrial fibrillation following mitral valve surgery with or without associated radiofrequency ablation

Background

This study reports the outcomes of patients who underwent electrical cardioversion for atrial fibrillation recurrence following mitral valve surgery and associated radiofrequency ablation compared to those who did not undergo concomitant atrial fibrillation ablation.

Methods

The population consisted of 116 patients with persistent/long-standing persistent AF who underwent mitral valve surgery with (Group A, n = 54) or without (Group B, n = 62) associated radiofrequency ablation between January 2007 and January 2011 at three institutions and who subsequently underwent cardioversion for persistent atrial fibrillation within 12 months of their initial procedure.

Results

The mean follow-up duration was 30.7 ± 9.4 months. Of the 104 patients with acute restoration of SR 42 (40.3%) had AF recurrence. The average time to recurrence after cardioversion was 7.3 ± 4.2 days. Recurrence was significantly lower in patients undergoing ablation surgery (21.4%) than in those undergoing no ablation surgery (78.6%, p < 0.001). Non-performed ablation procedure (p < 0.001), time from surgery ≥ 88 days and left atrial dimensions ≥ 45.5 mm before cardioversion (both, p = 0.005) were multivariable predictors of atrial fibrillation recurrence. In Group B the use of amiodarone was inversely correlated with recurrence of AF (p < 0.001). This correlation was not significant (r = − 0.02, p = 0.85) in Group A.

Conclusions

Electrical cardioversion for recurrent AF showed better results and stable recovery of sinus rhythm in patients undergoing concomitant surgical ablation during mitral valve surgery. This might be attributable to substrate modification caused by surgical lesions. Amiodarone improved the ECV-success rate only in patients with no associate ablation. Further larger randomized studies are necessary to confirm our findings.     

Validity of cardiac implantable electronic devices in assessing daily physical activity

Background

Data on physical activity assessed by cardiac implantable electronic devices (ICD/CRT) have been used for prognostic implications in heart failure patients, but no study has ever compared these data to validated external accelerometers.

Methods

73 ICD/CRT recipients (age 60 ± 20 years, 21% female) received a validated external accelerometer over a period of 7 days. Thereafter, data on physical activity of both ICD/CRT and external accelerometers were retrieved and compared using Spearman's rank correlation coefficient and Bland Altman plots.

Results

Mean total daily activity was 276 ± 85 min (range 72–462) as assessed by the external accelerometers and 237 ± 105 min (28–575) as assessed by the ICD/CRT activity sensors (p < 0.001). A strong, significant intra-individual correlation (r > 0.7) between the two measurements was observed in a majority (70%) of patients (p < 0.05 each). However, a Bland Altman plot revealed a broad variation of total daily activity between both methods (95% limits of agreement − 225 to 147 min), resulting in differences in the duration of daily activity up to several hours. In multivariate regression analysis, no influence of age, NYHA functional class, left ventricular ejection fraction, underlying disease or type of device on these differences was observed.

Conclusions

As compared to a validated external accelerometer, daily physical activity assessed by ICD/CRT devices shows strong intra-individual correlations, but differs substantially regarding the absolute amount of daily activity. Thus, using ICD/CRT activity data for more precise clinical or prognostic information without prior validation is of limited value.     

Determinants of exercise-induced pulmonary arterial hypertension in systemic sclerosis

Background

Exercise-induced pulmonary arterial hypertension (EIPH) in systemic sclerosis (SSc) has already been observed but its determinants remain unclear. The aim of this study was to determine the incidence and the determinants of EIPH in SSc.

Methods and results

We prospectively enrolled 63 patients with SSc (age 54 ± 3 years, 76% female) followed in CHU Sart-Tilman in Liège. All patients underwent graded semi-supine exercise echocardiography. Systolic pulmonary arterial pressure (sPAP) was derived from the peak velocity of the tricuspid regurgitation jet and adding the estimation of right atrial pressure, both at rest and during exercise. Resting pulmonary arterial hypertension (PH) was defined as sPAP > 35 mm Hg and EIPH as sPAP > 50 mm Hg during exercise. The following formulas were used: mean PAP (mPAP) = 0.61 × sPAP + 2, left atrial pressure (LAP) = 1.9 + 1.24 × left ventricular (LV) E/e′ and pulmonary vascular resistance (PVR) = (mPAP–LAP) / LV cardiac output (CO) and slope of mPAP–LVCO relationship = changes in mPAP / changes in LVCO. Resting PH was present in 3 patients (7%) and 21 patients developed EIPH (47%). Patients with EIPH had higher resting LAP (10.3 ± 2.2 versus 8.8 ± 2.3 mm Hg; p = 0.03), resting PVR (2.6 ± 0.8 vs. 1.4 ± 1.1 Woods units; p = 0.004), exercise LAP (13.3 ± 2.3 vs. 9 ± 1.7 mm Hg; p < 0.0001), exercise PVR (3.6 ± 0.7 vs. 2.1 ± 0.9 Woods units; p = 0.02) and slope of mPAP–LVCO (5.8 ± 2.4 vs. 2.9 ± 2.1 mm Hg/L/min; p < 0.0001). After adjustment for age and gender, exercise LAP (β = 3.1 ± 0.8; p = 0.001) and exercise PVR (β = 7.9 ± 1.7; p = 0.0001) were independent determinants of exercise sPAP.

Conclusion

EIPH is frequent in SSc patients and is mainly related to both increased exercise LV filling pressure and exercise PVR.     

Longitudinal strain curves in the RV free wall differ in morphology in patients with pulmonary hypertension compared to controls

Background

Previous studies using speckle tracking-derived strain for quantification of right ventricular (RV) function in pulmonary hypertension (PHT) have focused on the magnitude of global and regional peak longitudinal systolic strains (PLSS) and systolic strain-related indices of dyssynchrony. The aim of our study was to investigate the pattern of RV contraction and relaxation with the use of the contour and timing of strain and velocity curves in PHT.

Methods

The study population consisted of thirty‐seven patients with PHT (45 ± 18 years, 16 women) and thirty‐seven controls. A complete two-dimensional echo with speckle-tracking-derived longitudinal strain of the basal RV free wall and interventricular septum (IVS) was performed and the cycle length-corrected time to PLSS (SST) and time from PLSS to 50% of PLSS (systolic strain half time—SSHT) in both regions were calculated.

Results

Patients with PHT had significantly reduced PLSS (− 24.9 ± 2.0% vs − 43.2 ± 3.0%, p < 0.001) and increased SST (0.47 ± 0.02 vs 0.39 ± 0.02, p = 0.043) and SSHT (0.22 ± 0.02 vs 0.16 ± 0.02, p = 0.047) in the basal RV free wall compared to controls. Furthermore, peak systolic velocities were observed earlier in the cardiac cycle in both regions in patients with PHT compared to controls.

Conclusions

Longitudinal strain curves in the RV free wall reach peak values later in the cardiac cycle and return slower towards the baseline in PHT. Furthermore, peak systolic velocities are observed earlier in the cardiac cycle in both the basal RV free wall and the basal IVS. The above observations effectively illustrate changes in patterns of RV contraction and relaxation caused by PHT.