Clinical impacts of scar reduction on gated myocardial perfusion SPECT after cardiac resynchronization therapy.

BACKGROUND: It had not been reported that myocardial scar shown on gated myocardial perfusion SPECT (GMPS) might reduce after cardiac resynchronization therapy (CRT). In this study, we aim to investigate the clinical impact and characteristic of scar reduction (SR) after CRT. METHODS AND RESULTS: Sixty-one heart failure patients following standard indication for CRT received twice GMPS as pre- and post-CRT evaluations. The patients with an absolute reduction of scar ≥ 10% after CRT were classified as the SR group while the rest were classified as the non-SR group. The SR group (N = 22, 36%) showed more improvement on LV function (∆LVEF: 18.1 ± 12.4 vs 9.4 ± 9.9 %, P = 0.007, ∆ESV: - 91.6 ± 52.6 vs - 38.1 ± 46.5 mL, P < 0.001) and dyssynchrony (ΔPSD: - 26.19 ± 18.42 vs - 5.8 ± 23.0°, P < 0.001, Δ BW: - 128.7 ± 82.8 vs - 25.2 ± 109.0°, P < 0.001) than non-SR group (N = 39, 64%). Multivariate logistic regression analysis showed baseline QRSd (95% CI 1.019-1.100, P = 0.006) and pre-CRT Reduced Wall Thickening (RWT) (95% CI 1.016-1.173, P = 0.028) were independent predictors for the development of SR. CONCLUSION: More than one third of patients showed SR after CRT who had more post-CRT improvement on LV function and dyssynchrony than those without SR. Wider QRSd and higher RWT before CRT were related to the development of SR after CRT.

Effects of Ivabradine on Patients with Depressed Left Ventricular Function after Cardiac Resynchronization Therapy.

Background: The potential synergistic effect of ivabradine and cardiac resynchronization therapy (CRT) in heart failure (HF) patients has rarely been studied. We aimed to evaluate the clinical benefits of ivabradine in patients with left ventricular dysfunction following CRT implantation. Methods: Two hundred and thirty-one patients receiving CRT were consecutively enrolled between January 2014 and December 2018 from two HF centers. A total of 123 patients had left ventricular ejection fraction (LVEF) < 40% and resting sinus heart rate (HR) ≥ 75 bpm after six months of CRT implantation. Among these patients, 45 were treated with ivabradine (Group 1), and 78 did not receive ivabradine treatment (Group 2). Results: Baseline characteristics and prescription rates of HF medications other than ivabradine were similar between the two groups. In Group 1, the mean HR decreased from 82.2 ± 11.4 bpm to 76.3 ± 10.5 bpm (p = 0.012), and the mean LVEF increased from 29.9 ± 6.5% to 38.8 ± 12.4% (p < 0.001). Atrial pacing percentage, biventricular pacing percentage, and burden of atrial fibrillation (AF) were not significantly different between the two groups during the study period. The patients' daily physical activity increased significantly in Group 1 compared to Group 2 (Δ daily activity 0.4 ± 0.7 hours/day vs. -0.1 ± 7.2 hours/day, p < 0.001). Conclusions: Ivabradine could effectively reduce HR and improve physical activity. It was safe to use and did not increase AF burden or affect biventricular pacing percentage in CRT recipients.

Impact of cardiac reverse remodeling after cardiac resynchronization therapy assessed by myocardial perfusion imaging on ventricular arrhythmia.

BACKGROUND: Although cardiac resynchronization therapy (CRT) has been a useful treatment of heart failure, patients with CRT are still in risk of sudden cardiac death due to ventricular arrhythmia. The aim of this study was to investigate the impact of cardiac reverse remodeling after CRT on the prevalence of ventricular tachycardia or fibrillation (VT/VF). METHODS AND RESULTS: Forty-one heart failure patients (26 men, age 66 ± 10 years), who were implanted with CRT for at least 12 months, were enrolled. All patients received myocardial perfusion imaging (MPI) under CRT pacing to evaluate left ventricle (LV) function, dyssynchrony, and scar. VT/VF episodes during the follow-up period after MPI were recorded by the CRT devices. Sixteen patients (N = 16/41, 39%) were found to have VT/VF. Multivariate Cox regression analysis and receiver operating characteristic curve analysis showed that five risk factors were significant predictors of VT/VF, including increased left ventricle ejection fraction (LVEF) by ≤7% after CRT, low LVEF after CRT (≤30%), change of intrinsic QRS duration (iQRSd) by ≤7 ms, wide iQRSd after CRT (≥121 ms), and high systolic dyssynchrony after CRT (phase standard deviation ≥45.6°). For those patients with all of the 5 risk factors, 85.7% or more developed VT/VF. CONCLUSIONS: The characteristics of cardiac reverse remodeling after CRT as assessed by MPI are associated with the prevalence of ventricular arrhythmia.

Association between statin therapy and long-term clinical outcomes in patients with stable coronary disease undergoing percutaneous coronary intervention.

This longitudinal cohort study examined the long-term effect of statin therapy on clinical outcomes in patients undergoing percutaneous coronary intervention (PCI). A total of 1760 patients with stable coronary artery disease (CAD) were divided by receipt of statin therapy or not after index PCI. Baseline clinical characteristics, risk factors, angiographic findings, and medications after interventional procedure were assessed to compare long-term clinical outcomes between groups. Predictors for all-cause death and major adverse cardiovascular events (MACE), including myocardial infarction (MI), cardiovascular death, and repeated PCI procedures, were also analyzed. The statin therapy group had higher average serum cholesterol and more elevated low-density lipoprotein cholesterol (LDL-C) than the non-statin therapy group (189.0 ± 47.9 vs 169.3 ± 37.00 mg/dl, 117.2 ± 42.6 vs 98.7 ± 31.8 mg/dl, respectively, both P < 0.001). The non-statin group had higher rates of all-cause death and cardiovascular death compared to statin group (both P < 0.001). After adjustment for age, diabetes, and chronic kidney disease, Cox proportion hazard analysis revealed statin use significantly reduced all-cause death and repeated PCI procedure (hazard ratio: 0.53 and 0.69, respectively). Statin use seemed not reduce the hazard of cardiovascular death or MI in patients with stable CAD after PCI; however, statin therapy still was associated with reduced rates of all-cause death and repeat PCI procedure.

Left-ventricular dyssynchrony in viable myocardium by myocardial perfusion SPECT is predictive of mechanical response to CRT.

OBJECTIVES: Gated myocardial perfusion SPECT (GMPS) provides a one-stop-shop evaluation for cardiac resynchronization therapy (CRT). However, conflicting results have been observed regarding whether the baseline left-ventricular (LV) mechanical dyssynchrony as assessed by phase analysis on GMPS was predictive of therapeutic response to CRT. Since dyssynchrony parameters by phase analysis spuriously increased by scarred myocardium, the purpose of this study was to explore the value of dyssynchrony after stripping off the scar region in correlation to mechanical response to CRT. METHODS: Forty-seven patients following standard indications for CRT received GMPS with phase analysis as pre-CRT evaluation. A decrease of end-systolic volume (ESV) > 15% on follow-up echocardiography after CRT was considered as a mechanical response to CRT. Myocardial regions with less than 50% of maximal activity on GMPS were considered as a scar. The phase standard deviation (PSD) and histogram bandwidth (BW) without or with stripping off scar were assessed by phase analysis of GMPS and were used for evaluation of LV dyssynchrony of all myocardium or only the viable myocardium, respectively. RESULTS: No significant difference was noted between mechanical responders (31 of 47 patients, 66%) and nonresponders ( 16 of 47 patients, 34%) for PSD (48.6° ± 19.4° vs 43.9° ± 20.7°, p = 0.46) and BW (225° ± 91.1° vs 163.5° ± 94.6°, p = 0.38) of the entire myocardium. However, responders had significantly larger PSD (40.5° ± 15.7° vs 30.5° ± 13.2°, p = 0.03) and borderlinely larger BW (215° ± 91.2° vs. 139.5° ± 78.2°, p = 0.05) than non-responders after stripping off scar. Logistic regression analysis showed that scar area and PSD after stripping off scar were independent predictors of mechanical response. CONCLUSIONS: Our result showed that LV dyssynchrony of the entire myocardium did not predict response to CRT. However, LV dyssynchrony only in the viable myocardium was a significant predictor of CRT mechanical response.

Transient left bundle branch block and poor atrioventricular conduction during ablation of accessory pathway at the left ventricle.

A 56-year-old female with manifest Wolff-Parkinson-White (WPW) syndrome was sent to emergency room because of preexcited atrial fibrillation (AF) and became sinus rhythm after cardioversion. Then, she received catheter ablation of a left-sided lateral accessory pathway. The patient immediately developed Wenckebach atrioventricular (AV) block and left bundle branch block (LBBB) during the initial ablation. The ECG still showed LBBB 1 hour after ablation. The LBBB became narrow QRS (The QRS complex in the electrocardiogram. The QRS complex includes the Q wave, R wave, and S wave) 1 day later. Two weeks later, Holter's ECG showed normal sinus rhythm with 1:1 AV conduction even at the maximum heart rate of 125 beats/min. Transient LBBB and poor AV nodal conduction could occur during ablation by the trans-aortic approach.

LV Dyssynchrony Is Helpful in Predicting Ventricular Arrhythmia in Ischemic Cardiomyopathy After Cardiac Resynchronization Therapy: A Preliminary Study.

For patients with coronary artery disease, larger scar burdens are associated with higher risk of ventricular arrhythmia. Left ventricular (LV) dyssynchrony is associated with increased risk of sudden cardiac death in patients with heart failure. The purpose of this study was to assess the values of LV dyssynchrony and myocardial scar assessed by myocardial perfusion SPECT (MPS) in predicting the development of ventricular arrhythmia in ischemic cardiomyopathy. Twenty-two patients (16 males, mean age: 66 ±â€Š13) with irreversible ischemic cardiomyopathy received cardiac resynchronization therapy (CRT) for at least 12 months were enrolled for MPS. Quantitative parameters, including LV dyssynchrony with phase standard deviation (phase SD) and bandwidth, left ventricular ejection fraction (LVEF), and scar (% of total areas), were generated by Emory Cardiac Toolbox. Ventricular tachycardia (VT) and ventricular fibrillation (VF) recorded in the CRT device during follow-up were used as the reference standard of diagnosing ventricular arrhythmia. Stepwise logistic regression analysis was performed for determining the independent predictors of VT/VF and receiver operating characteristic (ROC) curve analysis was used for generating the optimal cut-off values for predicting VT/VF. Nine (41%) of the 22 patients developed VT/VF during the follow-up periods. Patients with VT/VF had significantly lower LVEF, larger scar, larger phase SD, and larger bandwidth (all P < 0.05). Logistic regression analysis showed LVEF and bandwidth were independent predictors of VT/VF. ROC curve analysis showed the areas under the curves were 0.71 and 0.83 for LVEF and bandwidth, respectively. The optimal cut-off values were <36% and > 139° for LVEF and bandwidth, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 39%, 53%, and 100%, respectively, for LVEF; and were 78%, 92%, 88%, and 86%, respectively, for bandwidth. LV dyssynchrony as assessed by phase analysis of MPS is helpful for predicting ventricular arrhythmia in ischemic cardiomyopathy after CRT. Further implantation of defibrillator may be considered for those patients with bandwidth >139°.

Relationship of myocardial substrate characteristics as assessed by myocardial perfusion imaging and cardiac reverse remodeling levels after cardiac resynchronization therapy.

BACKGROUND: Cardiac resynchronization therapy (CRT) can provide cardiac reverse remodeling (RR), which may include mechanical reverse remodeling (MRR) and/or electrical reverse remodeling (ERR). However, uncoupling of MRR and ERR is not uncommon, and the underlying mechanisms are not clear. This study aimed to evaluate the relationship of myocardial substrate characteristics as assessed by myocardial perfusion imaging (MPI) and cardiac RR post-CRT. MATERIALS AND METHODS: Forty-one patients (26 men, mean age 66 ± 10 years) with heart failure received CRT for at least 12 months were assigned to three groups according to their levels of RR: I, MRR + ERR (ESV reduced ≥15 % and intrinsic QRS duration reduced ≥10 ms); II, MRR only (ESV reduced ≥15 %); and III, non-responder (the others). All the patients also underwent MPI under transient CRT-off to evaluate the intrinsic myocardial substrates, including myocardial scar, LV volumes and function, systolic dyssynchrony, and activation sequences. In addition, ventricular tachycardia (VT) and ventricular fibrillation (VF) detected by the CRT devices during follow-up periods were also recorded. RESULTS: Quantitative analysis of MPI showed that there were significant differences for scar burden [15.9 ± 9.5, 26.8 ± 16.1, and 45.6 ± 15.1 % for group I (n = 15), II (n = 16), and III (n = 10), respectively, p < 0.001], EDV (136.6 ± 64.9, 221.6 ± 123.9, and 351.8 ± 216.3 ml, p = 0.002), ESV (82.6 ± 59.8, 172.3 ± 117.2, and 293.3 ± 209.6 ml, p = 0.001), LVEF (44.9 ± 15.0, 25.6 ± 10.9, and 21.5 ± 11.7 %, p < 0.001), systolic phase SD (23.4° ± 10.3°, 36.0° ± 16.2°, and 57.0° ± 22.2°, p < 0.001), and bandwidth (72.5° ± 31.1°, 113.4° ± 56.4°, and 199.1° ± 90.1°, p < 0.001). Myocardial scar interfered with the normal propagation of mechanical activation, resulting in heterogeneous activation sequences. Compared with group II (MRR only), group I (ERR + MRR) had significantly less initial activation segments (1.9 ± 1.0 vs. 2.6 ± 0.7, p < 0.05) and shorter maximal contraction delay (46.9° ± 12.9° vs. 58.8° ± 18.5°, p < 0.05). During the periods of follow-up, 21 patients developed VT/VF, including only 1 patient (1 VT) in group I (6.7 %), 8 patients (7 VT and 1 VF) in group II (50 %), and 9 patients (7 VT and 5 VF) in group III (90 %). CONCLUSION: The characteristics of myocardial substrates as assessed by MPI differed significantly between different levels of cardiac RR post-CRT. Myocardial scar played an important role in the development of ERR. Different cardiac RR levels contributed to different incidences of ventricular arrhythmia, and the combination of ERR and MRR provided highest anti-arrhythmic effects.

Relationship of quantitative parameters of myocardial perfusion SPECT and ventricular arrhythmia in patients receiving cardiac resynchronization therapy.

BACKGROUND: Ventricular arrhythmia is the major cause of sudden cardiac death for patients with heart failure, including those receiving implantation of cardiac resynchronization therapy (CRT). The purpose of this study was to assess the value of myocardial perfusion SPECT (MPS) in predicting ventricular arrhythmia for patients with CRT. METHODS AND METHODS: Fifty-one patients (35 males, mean age 64 ± 12 years) who had received CRT for at least 6 months were enrolled for resting gated MPS. Three main quantitative parameters of MPS, including extent of myocardial scar, left ventricular ejection fraction (LVEF) and LV dyssynchrony (phase SD), were generated by Emory Cardiac Toolbox. Using the recorded ventricular arrhythmia in the device, including ventricular tachycardia (VT) and ventricular fibrillation (VF), as the primary end point, the value of quantitative parameters of MPS in predicting the development of VT/VF was assessed. RESULTS: Twenty (39 %) of the 51 patients developed VT/VF during the follow-up (15.3 ± 12.7 months). The patients with VT/VF had significantly lower LVEF (24 ± 12 vs. 36 ± 17 %, p < 0.005), larger scar areas (36 ± 19 vs. 22 ± 12 %, p < 0.05) and larger phase SD (57° ± 20° vs. 43° ± 17°, p < 0.01). When categorizing the patients by the median values of LVEF, scar and phase SD, univariate regression analysis showed that lower LVEF (<29 %), larger scar (>23 %) and larger phase SD (>50°) were related to the development of VT/VF (p = 0.006, 0.011 and 0.064, respectively). However, only LVEF was marginally significant as an independent predictor of VT//VF on multivariate regression analysis (p = 0.0573). Survival analysis with Kaplan-Meier curves showed that the survival probability for VT/VF in those with LVEF >29 %, scar areas <23 % and phase SD < 50° was significantly better than in the others (HR 5.16, 95 % CI 1.20-22.16) by log-rank test (χ (2) = 5.9894, p = 0.014). CONCLUSION: Lower LVEF, larger scar and/or more dyssynchrony assessed by MPS were related to the development of ventricular arrhythmia for patients with CRT, and further defibrillator implantation may be considered for these patients.