Sex-Specific Response to Cardiac Resynchronization Therapy: Effect of Left Ventricular Size and QRS Duration in Left Bundle Branch Block

Performance of the Quadripolar CRT-D system: 5-Year Results from the Quadripolar Pacing Post Approval Study

BACKGROUND

Cardiac resynchronization therapy (CRT) is associated with challenges such as elevated capture thresholds, diaphragmatic stimulation, and lead instability.

OBJECTIVE

Assess the chronic safety and efficacy of the quadripolar CRT-D device system with the Quartet 1458Q Left Ventricular (LV) lead in a CRT-indicated population followed for 5 years and evaluate all-cause mortality and impact of baseline characteristics on survival through 5 years.

METHODS

Patients indicated for a CRT-D system were followed every 6 months post-implant for 5 years and assessed device performance and adverse events at each visit. The three primary endpoints were freedom from quadripolar CRT-D system-related complications through 5 years, freedom from Quartet 1458Q LV lead-related complications through 5 years, and the mean programmed pacing capture threshold at 5 years.

RESULTS

The study enrolled 1,970 subjects at 71 sites. The quadripolar CRT-D system was successfully implanted in 97.2% of subjects. Freedom from quadripolar CRT-D device system-related complications through 5 years was 89.7% and freedom from Quartet 1458Q LV lead-related complications through 5 years was 95.7%. 3.49 % of subjects had LV lead-related complications and an overall LV lead complication rate was 0.0122 events per subject-year. A mean LV pacing capture threshold was 1.52 ± 1.01 V at 5 years. The 5-year survival rate was 67.4%.

CONCLUSION

The quadripolar CRT-D system with the Quartet 1458Q LV lead exhibited low rates of complications and stable electrical performance through 5 years of follow-up and suggested a higher 5-year survival rate compared to traditional CRT systems.

Sex-related similarities and differences in responses to heart failure therapies

Although sex-related differences in the epidemiology, risk factors, clinical characteristics and outcomes of heart failure are well known, investigations in the past decade have shed light on an often overlooked aspect of heart failure: the influence of sex on treatment response. Sex-related differences in anatomy, physiology, pharmacokinetics, pharmacodynamics and psychosocial factors might influence the response to pharmacological agents, device therapy and cardiac rehabilitation in patients with heart failure. In this Review, we discuss the similarities between men and women in their response to heart failure therapies, as well as the sex-related differences in treatment benefits, dose-response relationships, and tolerability and safety of guideline-directed medical therapy, device therapy and cardiac rehabilitation. We provide insights into the unique challenges faced by men and women with heart failure, highlight potential avenues for tailored therapeutic approaches and call for sex-specific evaluation of treatment efficacy and safety in future research.

Heart Size Difference Drives Sex-Specific Response to Cardiac Resynchronization Therapy: A Post Hoc Analysis of the MORE-MPP CRT Trial

BACKGROUND

Studies have reported that female sex predicts superior cardiac resynchronization therapy (CRT) response. One theory is that this association is related to smaller female heart size, thus increased relative dyssynchrony at a given QRS duration (QRSd). Our objective was to investigate the mechanisms of sex-specific CRT response relating to heart size, relative dyssynchrony, cardiomyopathy type, QRS morphology, and other patient characteristics.

METHODS AND RESULTS

This is a post hoc analysis of the MORE-CRT MPP (More Response on Cardiac Resynchronization Therapy with Multipoint Pacing)  trial (n=3739, 28% women), with a subgroup analysis of patients with nonischemic cardiomyopathy and left bundle-branch block (n=1308, 41% women) to control for confounding characteristics. A multivariable analysis examined predictors of response to 6 months of conventional CRT, including sex and relative dyssynchrony, measured by QRSd/left ventricular end-diastolic volume (LVEDV). Women had a higher CRT response rate than men (70.1% versus 56.8%, P<0.0001). In subgroup analysis, regression analysis of the nonischemic cardiomyopathy left bundle-branch block subgroup identified QRSd/LVEDV, but not sex, as a modifier of CRT response (P<0.0039). QRSd/LVEDV was significantly higher in women (0.919) versus men (0.708, P<0.001). CRT response was 78% for female patients with QRSd/LVEDV greater than the median value, compared with 68% with QRSd/LVEDV less than the median value (P=0.012). The association between CRT response and QRSd/LVEDV was strongest at QRSd <150 ms.

CONCLUSIONS

In the nonischemic cardiomyopathy left bundle-branch block population, increased relative dyssynchrony in women, who have smaller heart sizes than their male counterparts, is a driver of sex-specific CRT response, particularly at QRSd <150 ms. Women may benefit from CRT at a QRSd <130 ms, opening the debate on whether sex-specific QRSd cutoffs or QRS/LVEDV measurement should be incorporated into clinical guidelines.

Clinical utility of QRS duration normalized to left ventricular volume for predicting cardiac resynchronization therapy efficacy in patients with "mid-range" QRS duration

BACKGROUND

Cardiac resynchronization therapy (CRT) is effective for patients with heart failure with QRS duration (QRSd) ≥150 ms. However, its beneficial effect seems to be limited for those with "mid-range" QRSd (120-149 ms). Recent studies have demonstrated that modifying QRSd to left ventricular end-diastolic volume (LVEDV)-modified QRSd-improves the prediction of clinical outcomes of CRT.

OBJECTIVE

The purpose of this study was to investigate the clinical impact of the modified QRSd on the efficacy of CRT in patients with "mid-range" QRSd.

METHODS

We conducted a retrospective, multicenter, observational study, with heart failure hospitalization (HFH) after CRT as the primary endpoint. Modified QRSd is defined as QRSd divided by LVEDV, determined through the Teichholtz method of echocardiography.

RESULTS

Among the 506 consecutive patients considered, 119 (mean age 61 ± 15 years; 80% male, QRSd 135 ± 9 ms) with a "mid-range" QRSd who underwent de novo CRT device implantation were included for analysis. During median follow-up of 878 days [interquartile range 381-1663 days], HFH occurred in 45 patients (37%). Fine-Gray analysis revealed modified QRSd was an independent predictor of HFH (hazard ratio [HR] 0.97; 95% confidence interval [CI] 0.96-0.99; P <.01). Receiver operating characteristic curve analysis revealed a cutoff value of 0.65 ms/mL for the modified QRSd in predicting HFH. Patients above the threshold exhibited a significantly lower incidence of HFH than patients below the threshold (HR 0.46; 95% CI 0.25-0.86; P = .01).

CONCLUSION

Modified QRSd can effectively predict the efficacy of CRT in patients with a "mid-range" QRSd.

Relationship between sex, body size, and cardiac resynchronization therapy benefit: A patient-level meta-analysis of randomized controlled trials

BACKGROUND

Women might benefit more than men from cardiac resynchronization therapy (CRT) and do so at shorter QRS durations.

OBJECTIVE

This meta-analysis was performed to determine whether sex-based differences in CRT effects are better accounted for by height, body surface area (BSA), or left ventricular end-diastolic dimension (LVEDD).

METHODS

We analyzed patient-level data from CRT trials (MIRACLE, MIRACLE ICD, MIRACLE ICD II, REVERSE, RAFT, COMPANION, and MADIT-CRT) using bayesian hierarchical Weibull regression models. Relationships between QRS duration and CRT effects were examined overall and in sex-stratified cohorts; additional analyses indexed QRS duration by height, BSA, or LVEDD. End points were heart failure hospitalization (HFH) or death and all-cause mortality.

RESULTS

Compared with men (n = 5628), women (n = 1439) were shorter (1.62 [interquartile range, 1.57-1.65] m vs 1.75 [1.70-1.80] m; P < .001), with smaller BSAs (1.76 [1.62-1.90] m2 vs 2.02 [1.89-2.16] m2; P < .001). In adjusted sex-stratified analyses, the reduction in HFH or death was greater for women (hazard ratio, 0.54; credible interval, 0.42-0.70) than for men (hazard ratio, 0.77; credible interval, 0.66-0.89; Pinteraction = .009); results were similar for all-cause mortality even after adjustment for height, BSA, and LVEDD. Sex-specific differences were observed only in nonischemic cardiomyopathy. The effect of CRT on HFH or death was observed at a shorter QRS duration for women (126 ms) than for men (145 ms). Indexing QRS duration by height, BSA, or LVEDD attenuated sex-specific QRS duration thresholds for the effects of CRT on HFH or death but not on mortality.

CONCLUSION

Although body size partially explains sex-specific QRS duration thresholds for CRT benefit, it is not associated with the magnitude of CRT benefit. Indexing QRS duration for body size might improve selection of patients for CRT, particularly with a "borderline" QRS duration.

Interaction of left ventricular size with the outcome of cardiac resynchronization therapy in Japanese patients

BACKGROUND

We analyzed the influence of the QRS duration (QRSd) to LV end-diastolic volume (LVEDV) ratio on cardiac resynchronization therapy (CRT) outcomes in heart failure patients classified as III/IV per the New York Heart Association (NYHA) and with small body size.

HYPOTHESIS

We proposed the hypothesis that the QRSd/LV size ratio is a better index of the CRT substrate.

METHODS

We enrolled 114 patients with advanced heart failure (NYHA class III/IV, and LV ejection fraction >35%) who received a CRT device, including those with left bundle branch block (LBBB) and QRSd ≥120 milliseconds (n = 60), non-LBBB and QRSd ≥150 milliseconds (n = 30) and non-LBBB and QRSd of 120-149 milliseconds (n = 24).

RESULTS

Over a mean follow-up period of 65 ± 58 months, the incidence of the primary endpoint, a composite of all-cause death and hospitalization for heart failure, showed no significant intergroup difference (43.3% vs. 50.0% vs. 37.5%, respectively, p = .72). Similarly, among 104 patients with QRSd/LVEDV ≥ 0.67 (n = 54) and QRSd/LVEDV < 0.67 (n = 52), no significant differences were observed in the incidence of the primary endpoint (35.1% vs. 51.9%, p = .49). Nevertheless, patients with QRSd/LVEDV ≥ 0.67 showed better survival than those with QRSd/LVEDV < 0.67 (14.8% vs. 34.6%, p = .0024).

CONCLUSION

Advanced HF patients with a higher QRSd/LVEDV ratio showed better survival in this small-body-size population. Thus, the risk is concentrated among those with a larger QRSd, and patients with a relatively smaller left ventricular size appeared to benefit from CRT.

LBBB and heart failure-Relationships among QRS amplitude, duration, height, LV mass, and sex

BACKGROUND

Height, left ventricular (LV) size, and sex were proposed as additional criteria for patient selection for cardiac resynchronization therapy (CRT) but their connections with the QRS complex in left bundle branch block (LBBB) are little investigated. We evaluated these.

METHODS

Among patients with "true" LBBB, QRS duration (QRSd) and amplitude, and LV hypertrophy indices, were correlated with patient's height and LV mass, and compared between sexes.

RESULTS

In this study cohort (n = 220; 60 ± 12 years; left ventricular ejection fraction [LVEF] 21 ± 7%; mostly New York Heart Association II-III, QRSd 165 ± 19 ms; 57% female; 70% responders [LVEF increased ≥5%]), LV mass was increased in all patients. QRS amplitude did not correlate with LV mass or height in any individual lead or with Sokolow-Lyon or Cornell-Lyon indices. QRSd did not correlate with height. In contrast, QRSd correlated strongly with LV mass (r = .51). CRT response rate was greater in women versus men (84% vs. 58%, p < .001) despite shorter QRSd [7% shorter (p < .0001)]. QRSd normalized for height resulted in a 2.7% and for LV mass 24% greater index in women.

CONCLUSION

True LBBB criteria do not exclude HF patients with increased LV mass. QRS amplitudes do not correlate with height or LV mass. Height does not affect QRSd. However, QRSd correlates with LV size. QRSd normalized for LV mass results in 24% greater value in women in the direction of sex-specific responses. LV mass may be a significant nonelectrical modifier of QRSd for CRT.

ISE/ISHNE expert consensus statement on the ECG diagnosis of left ventricular hypertrophy: The change of the paradigm

The ECG diagnosis of LVH is predominantly based on the QRS voltage criteria. The classical paradigm postulates that the increased left ventricular mass generates a stronger electrical field, increasing the leftward and posterior QRS forces, reflected in the augmented QRS amplitude. However, the low sensitivity of voltage criteria has been repeatedly documented. We discuss possible reasons for this shortcoming and proposal of a new paradigm. The theoretical background for voltage measured at the body surface is defined by the solid angle theorem, which relates the measured voltage to spatial and non-spatial determinants. The spatial determinants are represented by the extent of the activation front and the distance of the recording electrodes. The non-spatial determinants comprise electrical characteristics of the myocardium, which are comparatively neglected in the interpretation of the QRS patterns. Various clinical conditions are associated with LVH. These conditions produce considerable diversity of electrical properties alterations thereby modifying the resultant QRS patterns. The spectrum of QRS patterns observed in LVH patients is quite broad, including also left axis deviation, left anterior fascicular block, incomplete and complete left bundle branch blocks, Q waves, and fragmented QRS. Importantly, the QRS complex can be within normal limits. The new paradigm stresses the electrophysiological background in interpreting QRS changes, i.e., the effect of the non-spatial determinants. This postulates that the role of ECG is not to estimate LV size in LVH, but to understand and decode the underlying electrical processes, which are crucial in relation to cardiovascular risk assessment.

Association of vectorcardiographic T-wave area with clinical and echocardiographic outcomes in cardiac resynchronization therapy

AIMS

Data on repolarization parameters in cardiac resynchronization therapy (CRT) are scarce. We investigated the association of baseline T-wave area, with both clinical and echocardiographic outcomes of CRT in a large, multi-centre cohort of CRT recipients. Also, we evaluated the association between the baseline T-wave area and QRS area.

METHODS AND RESULTS

In this retrospective study, 1355 consecutive CRT recipients were evaluated. Pre-implantation T-wave and QRS area were calculated from vectorcardiograms. Echocardiographic response was defined as a reduction of ≥15% in left ventricular end-systolic volume between 3 and 12 months after implantation. The clinical outcome was a combination of all-cause mortality, heart transplantation, and left ventricular assist device implantation. Left ventricular end-systolic volume reduction was largest in patients with QRS area ≥ 109 μVs and T-wave area ≥ 66 μVs compared with QRS area ≥ 109 μVs and T-wave area < 66 μVs (P = 0.004), QRS area < 109 μVs and T-wave area ≥ 66 μVs (P < 0.001) and QRS area < 109 μVs and T-wave area < 66 μVs (P < 0.001). Event-free survival rate was higher in the subgroup of patients with QRS area ≥ 109 μVs and T-wave area ≥ 66 μVs (n = 616, P < 0.001) and QRS area ≥ 109 μVs and T-wave area < 66 μVs (n = 100, P < 0.001) than the other subgroups. In the multivariate analysis, T-wave area remained associated with echocardiographic response (P = 0.008), but not with the clinical outcome (P = 0.143), when QRS area was included in the model.

CONCLUSION

Baseline T-wave area has a significant association with both clinical and echocardiographic outcomes after CRT. The association of T-wave area with echocardiographic response is independent from QRS area; the association with clinical outcome, however, is not.

ISE/ISHNE Expert Consensus Statement on ECG Diagnosis of Left Ventricular Hypertrophy: The Change of the Paradigm. The joint paper of the International Society of Electrocardiology and the International Society for Holter Monitoring and Noninvasive Electrocardiology

The ECG diagnosis of LVH is predominantly based on the QRS voltage criteria, i.e. the increased QRS complex amplitude in defined leads. The classical ECG diagnostic paradigm postulates that the increased left ventricular mass generates a stronger electrical field, increasing the leftward and posterior QRS forces. These increased forces are reflected in the augmented QRS amplitude in the corresponding leads. However, the clinical observations document increased QRS amplitude only in the minority of patients with LVH. The low sensitivity of voltage criteria has been repeatedly documented. We discuss possible reasons for this shortcoming and proposal of a new paradigm.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

Sex-based differences in cardiac resynchronization therapy upgrade and outcome for patients with pacemaker and new-onset heart failure

BACKGROUND

Patients with chronic right ventricular (RV) pacing are at an increased risk of heart failure. Previous studies have indicated that cardiac resynchronization therapy (CRT) is underused in this setting, and that there may be sex-based differences in both CRT use and clinical outcome.

OBJECTIVE

To evaluate sex-based differences in CRT use and clinical outcome for patients with new-onset heart failure post RV pacing.

METHODS

Data from the Swedish pacemaker registry was matched with data from the national death and disease registries. Patients with de novo pacemaker implant due to AV block during the period 2005-2020 were included. New-onset heart-failure within two years post-implant was evaluated, primary outcome was all-cause mortality.

RESULTS

In all, 30183 patients (37% female) were included. Women were on average 3 years older, but had less comorbidities than men. Median follow-up time was 4.5 [2.0-8.0] years. Women had better age- and comorbidity-adjusted survival (HR 0.78 [0.73-0.84], p < .001). For the 3560 patients (12.4% men and 10.7% women, p < .001) who were diagnosed with new-onset heart failure, 5-year mortality was similar for men and women (50% vs. 48%, p = .29). However, women were less likely to receive CRT-upgrade (3.8% vs. 9.1%, p < .001), and those who did were almost ten years younger than the men.

CONCLUSION

Women with pacemaker due to AV block are older but have less comorbidities than men. They are less likely to develop new-onset heart failure, but also less likely to receive a CRT upgrade if they do develop heart failure. Increased awareness of the positive effects of CRT upgrade and potential sex- and age-based discrimination is warranted.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

Cardiac Resynchronization Therapy Improves Outcomes in Patients With Intraventricular Conduction Delay But Not Right Bundle Branch Block: A Patient-Level Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Benefit from cardiac resynchronization therapy (CRT) varies by QRS characteristics; individual randomized trials are underpowered to assess benefit for relatively small subgroups.

METHODS

The authors analyzed patient-level data from pivotal CRT trials (MIRACLE [Multicenter InSync Randomized Clinical Evaluation], MIRACLE-ICD [Multicenter InSync ICD Randomized Clinical Evaluation], MIRACLE-ICD II [Multicenter InSync ICD Randomized Clinical Evaluation II], REVERSE [Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction], RAFT [Resynchronization-Defibrillation for Ambulatory Heart Failure], BLOCK-HF [Biventricular Versus Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block], COMPANION [Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure], and MADIT-CRT [Multicenter Automatic Defibrillator Implantation Trial - Cardiac Resynchronization Therapy]) using Bayesian Hierarchical Weibull survival regression models to assess CRT benefit by QRS morphology (left bundle branch block [LBBB], n=4549; right bundle branch block [RBBB], n=691; and intraventricular conduction delay [IVCD], n=1024) and duration (with 150-ms partition). The continuous relationship between QRS duration and CRT benefit was also examined within subgroups defined by QRS morphology. The primary end point was time to heart failure hospitalization (HFH) or death; a secondary end point was time to all-cause death.

RESULTS

Of 6264 patients included, 25% were women, the median age was 66 [interquartile range, 58 to 73] years, and 61% received CRT (with or without an implantable cardioverter defibrillator). CRT was associated with an overall lower risk of HFH or death (hazard ratio [HR], 0.73 [credible interval (CrI), 0.65 to 0.84]), and in subgroups of patients with QRS ≥150 ms and either LBBB (HR, 0.56 [CrI, 0.48 to 0.66]) or IVCD (HR, 0.59 [CrI, 0.39 to 0.89]), but not RBBB (HR 0.97 [CrI, 0.68 to 1.34]; Pinteraction <0.001). No significant association for CRT with HFH or death was observed when QRS was <150 ms (regardless of QRS morphology) or in the presence of RBBB. Similar relationships were observed for all-cause death.

CONCLUSIONS

CRT is associated with reduced HFH or death in patients with QRS ≥150 ms and LBBB or IVCD, but not for those with RBBB. Aggregating RBBB and IVCD into a single "non-LBBB" category when selecting patients for CRT should be reconsidered.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifiers: NCT00271154, NCT00251251, NCT00267098, and NCT00180271.

Determinants of the time-to-peak left ventricular dP/dt (Td) and QRS duration with different fusion strategies in cardiac resynchronization therapy

Background

Cardiac resynchronization therapy (CRT) is helpful in selected patients; however, responder rates rarely exceed 70%. Optimization of CRT may therefore benefit a large number of patients. Time-to-peak dP/dt (Td) is a novel marker of myocardial synergy that reflects the degree of myocardial dyssynchrony with the potential to guide and optimize treatment with CRT. Optimal electrical activation is a prerequisite for CRT to be effective. Electrical activation can be altered by changing the electrical wave-front fusion resulting from pacing to optimize resynchronization. We designed this study to understand the acute effects of different electrical wave-front fusion strategies and LV pre-/postexcitation on Td and QRS duration (QRSd). A better understanding of measuring and optimizing resynchronization can help improve the benefits of CRT.

Methods

Td and QRSd were measured in 19 patients undergoing a CRT implantation. Two biventricular pacing groups were compared: pacing the left ventricle (LV) with fusion with intrinsic right ventricular activation (FUSION group) and pacing the LV and right ventricle (RV) at short atrioventricular delay (STANDARD group) to avoid fusion with intrinsic RV activation. A quadripolar LV lead enabled pacing from widely separated electrodes; distal (DIST), proximal (PROX) and both electrodes combined (multipoint pacing, MPP). The LV was stimulated relative in time to RV activation (either RV pace-onset or QRS-onset), with the LV stimulated prior to (PRE), simultaneous with (SIM) or after (POST) RV activation. In addition, we analyzed the interactions of the two groups (FUSION/STANDARD) with three different electrode configurations (DIST, PROX, MPP), each paced with three different degrees of LV pre-/postexcitation (PRE, SIM, POST) in a statistical model.

Results

We found that FUSION provided shorter Td and QRSd than STANDARD, MPP provided shorter Td and QRSd than DIST and PROX, and SIM provided both the shortest QRSd and Td compared to PRE and POST. The interaction analysis revealed that pacing MPP with fusion with intrinsic RV activation simultaneous with the onset of the QRS complex (MPP^*FUSION^*SIM) shortened QRSd and Td the most compared to all other modes and configurations. The difference in QRSd and Td from their respective references were significantly correlated (β = 1, R = 0.9, p < 0.01).

Conclusion

Pacing modes and electrode configurations designed to optimize electrical wave-front fusion (intrinsic RV activation, LV multipoint pacing and simultaneous RV and LV activation) shorten QRSd and Td the most. As demonstrated in this study, electrical and mechanical measures of resynchronization are highly correlated. Therefore, Td can potentially serve as a marker for CRT optimization.

Impact of corticosteroid use on the clinical response and prognosis in patients with cardiac sarcoidosis who underwent an upgrade to cardiac resynchronization therapy

Background

Corticosteroids are widely used in patients with cardiac sarcoidosis (CS). In addition, upgrading to cardiac resynchronization therapy (CRT) is sometimes needed. This study aimed to investigate the impact of corticosteroid use on the clinical outcomes following CRT upgrades.

Methods

A total of 48 consecutive patients with non‐ischemic cardiomyopathies who underwent CRT upgrades were retrospectively reviewed and divided into three groups: group 1 included CS patients taking corticosteroids before the CRT upgrade (n = 7), group 2, CS patients not taking corticosteroids before the CRT upgrade (n = 10), and group 3, non‐CS patients (n = 31). The echocardiographic response, heart failure hospitalizations, and cardiovascular deaths were evaluated.

Results

The baseline characteristics during CRT upgrades exhibited no significant differences in the echocardiographic data between the three groups. After the CRT upgrade, responses regarding the ejection fraction (EF) and end‐systolic volume (ESV) were significantly lower in CS patients than non‐CS patients (ΔEF: group 1, 6.7% vs. group 2, 7.7% vs. group 3, 13.6%; p = .039, ΔESV: 3.0 ml vs. ‐12.7 ml vs. ‐37.2 ml; p = .008). The rate of an echocardiographic response was lowest in group 1 (29%). There were, however, no significant differences in the cumulative freedom from a composite outcome among the three groups (p = .19). No cardiovascular deaths occurred in group 1.

Conclusion

The echocardiographic response to an upgrade to CRT and the long‐term prognosis in patients with CS should be carefully evaluated because of the complex etiologies and impact of immunosuppressive therapy.

OUP accepted manuscript

Electrical disturbances, such as atrial fibrillation (AF), dyssynchrony, tachycardia, and premature ventricular contractions (PVCs), are present in most patients with heart failure (HF). While these disturbances may be the consequence of HF, increasing evidence suggests that they may also cause or aggravate HF. Animal studies show that longer-lasting left bundle branch block, tachycardia, AF, and PVCs lead to functional derangements at the organ, cellular, and molecular level. Conversely, electrical treatment may reverse or mitigate HF. Clinical studies have shown the superiority of atrial and pulmonary vein ablation for rhythm control and AV nodal ablation for rate control in AF patients when compared with medical treatment. Ablation of PVCs can also improve left ventricular function. Cardiac resynchronization therapy (CRT) is an established adjunct therapy currently undergoing several interesting innovations. The current guideline recommendations reflect the safety and efficacy of these ablation therapies and CRT, but currently, these therapies are heavily underutilized. This review focuses on the electrical treatment of HF with reduced ejection fraction (HFrEF). We believe that the team of specialists treating an HF patient should incorporate an electrophysiologist in order to achieve a more widespread use of electrical therapies in the management of HFrEF and should also include individual conditions of the patient, such as body size and gender in therapy fine-tuning.

Shortening of time-to-peak left ventricular pressure rise (Td) in cardiac resynchronization therapy

Aims

We tested the hypothesis that shortening of time‐to‐peak left ventricular pressure rise (Td) reflect resynchronization in an animal model and that Td measured in patients will be helpful to identify long‐term volumetric responders [end‐systolic volume (ESV) decrease >15%] in cardiac resynchronization therapy (CRT).

Methods

Td was analysed in an animal study (n = 12) of left bundle‐branch block (LBBB) with extensive instrumentation to detect left ventricular myocardial deformation, electrical activation, and pressures during pacing. The sum of electrical delays from the onset of pacing to four intracardiac electrodes formed a synchronicity index (SI). Pacing was performed at baseline, with LBBB, right and left ventricular pacing and finally with biventricular pacing (BIVP). We then studied Td at baseline and with BIVP in a clinical observational study in 45 patients during the implantation of CRT and followed up for up to 88 months.

Results

We found a strong relationship between Td and SI in the animals (R = 0.84, P < 0.01). Td and SI increased from narrow QRS at baseline (Td = 95 ± 2 ms, SI = 141 ± 8 ms) to LBBB (Td = 125 ± 2 ms, SI = 247 ± 9 ms, P < 0.01), and shortened with biventricular pacing (BIVP) (Td = 113 ± 2 ms and SI = 192 ± 7 ms, P < 0.01). Prolongation of Td was associated with more wasted deformation during the preejection period (R = 0.77, P < 0.01). Six patients increased ESV by 2.5 ± 18%, while 37 responders (85%) had a mean ESV decrease of 40 ± 15% after more than 6 months of follow‐up. Responders presented with a higher Td at baseline than non‐responders (163 ± 26 ms vs. 121 ± 19 ms, P < 0.01). Td decreased to 156 ± 16 ms (P = 0.02) with CRT in responders, while in non‐responders, Td increased to 148 ± 21 ms (P < 0.01). A decrease in Td with BIVP to values similar or below what was found at baseline accurately identified responders to therapy (AUC 0.98, P < 0.01). Td at baseline and change in Td from baseline was linear related to the decrease in ESV at follow‐up. All‐cause mortality was high among six non‐responders (n = 4), while no patients died in the responder group during follow‐up.

Conclusions

Prolongation of Td is associated with cardiac dyssynchrony and more wasted deformation during the preejection period. Shortening of a prolonged Td with CRT in patients accurately identifies volumetric responders to CRT with incremental value on top of current guidelines and practices. Thus, Td carries the potential to become a biomarker to predict long‐term volumetric response in CRT candidates.

Right ventricular dilatation and systolic dysfunction and relationship to QRS duration in patients with left bundle branch block and cardiomyopathy

BACKGROUND

Marked QRS widening in patients with left bundle branch block (LBBB) may reduce efficacy of cardiac resynchronization therapy (CRT). We hypothesized that extreme QRS prolongation may accompany right ventricular (RV) dilatation/systolic dysfunction (RVD/RVsD) as well as left ventricular dilatation/systolic dysfunction (LVD/LVsD).

METHODS

We assessed rates of both ventricular dilatation and systolic dysfunction according to widening of QRS duration (QRSd) in 100 consecutive cardiomyopathy patients with true LBBB (QRSd ≥ 130 ms in female or ≥140 ms in male, QS or rS in leads V1/V2, and mid-QRS notching/slurring in ≥2 contiguous leads of I, aVL, and V1/V2/V5/V6). Ventricular dimensions and function were measured by cardiac magnetic resonance imaging.

RESULTS

There was a trend toward an increase in the prevalence of LVD (13%, 20%, and 90%), LVsD (67%, 77%, and 90%), RVD (23%, 27%, and 50%), RVsD (27%, 27%, and 40%), RVD plus RVsD (13%, 17%, and 40%), or RVD/RVsD (37%, 37%, and 50%) according to the degree of QRS prolongation (<150 ms, n = 30; 150-180 ms, n = 60; and ≥180 ms, n = 10). Similarly, patients in the highest quartile of QRSd (QRSd ≥ 168 ms, n = 26) showed greater rates of RVD (23% vs. 44%, p = .069), RVsD (22% vs. 48%, p = .032), RVD plus RVsD (10% vs. 30%, p = .040), or RVD/RVsD (33% vs. 57%, p = .050) compared to those in the remaining quartiles (n = 74). QRSd ≥ 180 ms was identified as an independent predictor for the presence of RVD plus RVsD.

CONCLUSION

The rates of RVD and/or RVsD increased with QRS widening, particularly when QRSd exceeded 180 ms. This may diminish anticipated CRT response rates in cardiomyopathy patients with LBBB.

Optimized implementation of cardiac resynchronization therapy: a call for action for referral and optimization of care

Cardiac resynchronization therapy (CRT) is one of the most effective therapies for heart failure with reduced ejection fraction and leads to improved quality of life, reductions in heart failure hospitalization rates and all-cause mortality. Nevertheless, up to two-thirds of eligible patients are not referred for CRT. Furthermore, post-implantation follow-up is often fragmented and suboptimal, hampering the potential maximal treatment effect. This joint position statement from three European Society of Cardiology Associations, Heart Failure Association (HFA), European Heart Rhythm Association (EHRA) and European Association of Cardiovascular Imaging (EACVI), focuses on optimized implementation of CRT. We offer theoretical and practical strategies to achieve more comprehensive CRT referral and post-procedural care by focusing on four actionable domains: (i) overcoming CRT under-utilization, (ii) better understanding of pre-implant characteristics, (iii) abandoning the term 'non-response' and replacing this by the concept of disease modification, and (iv) implementing a dedicated post-implant CRT care pathway.

Optimized implementation of cardiac resynchronization therapy: a call for action for referral and optimization of care: A joint position statement from the Heart Failure Association (HFA), European Heart Rhythm Association (EHRA), and European Association of Cardiovascular Imaging (EACVI) of the European Society of Cardiology

Cardiac resynchronization therapy (CRT) is one of the most effective therapies for heart failure with reduced ejection fraction and leads to improved quality of life, reductions in heart failure hospitalization rates and all-cause mortality. Nevertheless, up to two-thirds of eligible patients are not referred for CRT. Furthermore, post-implantation follow-up is often fragmented and suboptimal, hampering the potential maximal treatment effect. This joint position statement from three European Society of Cardiology Associations, Heart Failure Association (HFA), European Heart Rhythm Association (EHRA) and European Association of Cardiovascular Imaging (EACVI), focuses on optimized implementation of CRT. We offer theoretical and practical strategies to achieve more comprehensive CRT referral and post-procedural care by focusing on four actionable domains: (i) overcoming CRT under-utilization, (ii) better understanding of pre-implant characteristics, (iii) abandoning the term 'non-response' and replacing this by the concept of disease modification, and (iv) implementing a dedicated post-implant CRT care pathway.

Changes in cardiac conduction time following cardiac resynchronization therapy: rationale and design of the RECOVER study

BACKGROUND

It has been known that ventricular conduction delays play a key role in the cardiac resynchronization therapy (CRT) response of patients with advanced heart failure (HF). However, no study to our knowledge has yet evaluated the serial changes in conduction times measured between different electrodes of CRT devices.

METHODS AND RESULTS

The Reduction or Extension of Conduction Time with Ventricular Electromechanical Remodeling (RECOVER) study (NCT04397224) was designed to investigate serial changes in interelectrode conduction times and to elucidate their prognostic value. We plan to enroll 100 patients implanted with CRT systems with endocardial quadripolar left ventricular leads. Patients will be scheduled for follow-up every 3 months over a period of 2 years, where they will undergo measurement of interelectrode conduction times to evaluate their serial changes. The primary outcome of the RECOVER study is the correlation between the degree of conduction time changes and the CRT response as defined by echocardiography. The time course and prognostic value of the serial changes in conduction times will be investigated as well.

CONCLUSION

The RECOVER study is investigating whether serial changes in interelectrode conduction times can be useful parameters in predicting the CRT response or detecting worsening HF at an early stage.

Electroanatomic Ratios and Mortality in Patients With Heart Failure: Insights from the ASIAN-HF Registry

Background

QRS duration (QRSd) is a marker of electrical remodeling in heart failure. Anthropometrics and left ventricular size may influence QRSd and, in turn, may influence the association between QRSd and heart failure outcomes.

Methods and Results

Using the prospective, multicenter, multinational ASIAN‐HF (Asian Sudden Cardiac Death in Heart Failure) registry, this study evaluated whether electroanatomic ratios (QRSd indexed for height or left ventricular end‐diastole volume) are associated with 1‐year mortality in individuals with heart failure with reduced ejection fraction. The study included 4899 individuals (aged 60±19 years, 78% male, mean left ventricular ejection fraction: 27.3±7.1%). In the overall cohort, QRSd was not associated with all‐cause mortality (hazard ratio [HR], 1.003; 95% CI, 0.999–1.006, P=0.142) or sudden cardiac death (HR, 1.006; 95% CI, 1.000–1.013, P=0.059). QRS/height was associated with all‐cause mortality (HR, 1.165; 95% CI, 1.046–1.296, P=0.005 with interaction by sex p_interaction=0.020) and sudden cardiac death (HR, 1.270; 95% CI, 1.021–1.580, P=0.032). QRS/left ventricular end‐diastole volume was associated with all‐cause mortality (HR, 1.22; 95% CI, 1.05–1.43, P=0.011) and sudden cardiac death (HR, 1.461; 95% CI, 1.090–1.957, P=0.011) in patients with nonischemic cardiomyopathy but not in patients with ischemic cardiomyopathy (all‐cause mortality: HR, 0.94; 95% CI, 0.79–1.11, P=0.467; sudden cardiac death: HR, 0.734; 95% CI, 0.477–1.132, P=0.162).

Conclusions

Electroanatomic ratios of QRSd indexed for body size or left ventricular size are associated with mortality in individuals with heart failure with reduced ejection fraction. In particular, increased QRS/height may be a marker of high risk in individuals with heart failure with reduced ejection fraction, and QRS/left ventricular end‐diastole volume may further risk stratify individuals with nonischemic heart failure with reduced ejection fraction.

Registration

URL: https://Clinicaltrials.gov. Unique identifier: NCT01633398.

Sex-Specific Patterns of Mortality Predictors Among Patients Undergoing Cardiac Resynchronization Therapy: A Machine Learning Approach

Background: The relative importance of variables explaining sex-related differences in outcomes is scarcely explored in patients undergoing cardiac resynchronization therapy (CRT). We sought to implement and evaluate machine learning (ML) algorithms for the prediction of 1- and 3-year all-cause mortality in CRT patients. We also aimed to assess the sex-specific differences in predictors of mortality utilizing ML. Methods: Using a retrospective registry of 2,191 CRT patients, ML models were implemented in 6 partially overlapping patient subsets (all patients, females, or males with 1- or 3-year follow-up). Each cohort was randomly split into training (80%) and test sets (20%). After hyperparameter tuning in the training sets, the best performing algorithm was evaluated in the test sets. Model discrimination was quantified using the area under the receiver-operating characteristic curves (AUC). The most important predictors were identified using the permutation feature importances method. Results: Conditional inference random forest exhibited the best performance with AUCs of 0.728 (0.645-0.802) and 0.732 (0.681-0.784) for the prediction of 1- and 3-year mortality, respectively. Etiology of heart failure, NYHA class, left ventricular ejection fraction, and QRS morphology had higher predictive power, whereas hemoglobin was less important in females compared to males. The importance of atrial fibrillation and age increased, while the importance of serum creatinine decreased from 1- to 3-year follow-up in both sexes. Conclusions: Using ML techniques in combination with easily obtainable clinical features, our models effectively predicted 1- and 3-year all-cause mortality in CRT patients. Sex-specific patterns of predictors were identified, showing a dynamic variation over time.

Left Ventricular Enlargement, Cardiac Resynchronization Therapy Efficacy, and Impact of MultiPoint Pacing

Background:

Left ventricular (LV) epicardial pacing results in slowly propagating paced wavefronts. We postulated that this effect might limit cardiac resynchronization therapy efficacy in patients with LV enlargement using conventional biventricular pacing with single-site LV pacing, but be mitigated by LV stimulation from 2 widely spaced sites using MultiPoint pacing with wide anatomic separation (MPP-AS: ≥30 mm). We tested this hypothesis in the multicenter randomized MPP investigational device exemption trial.

Methods:

Following implant, quadripolar biventricular single-site pacing was activated in all patients (n=506). From 3 to 9 months postimplant, among patients with available baseline LV end-diastolic volume (LVEDV) measures, 188 received biventricular single-site pacing and 43 received MPP-AS. Patients were dichotomized by median baseline LVEDV indexed to height (LVEDVI Median ). Outcomes were measured by the clinical composite score (primary efficacy end point), quality of life, LV structural remodeling (↑EF >5% and ↓ESV 10%) and heart failure event/cardiovascular death.

Results:

LVEDVI Median was 1.1 mL/cm. Baseline characteristics differed in patients with LVEDVI >Median versus LVEDVI ≤Median . Among patients with LVEDVI >Median , biventricular single-site pacing was less efficacious compared to patients with LVEDVI ≤Median (clinical composite score, 65% versus 79%). In contrast, MPP-AS programming generated greater clinical composite score response (92% versus 65%, P =0.023) and improved quality of life (−31.0±29.7 versus −15.7±22.1, P =0.038) versus biventricular single-site pacing in patients with LVEDVI >Median . Reverse remodeling trended better with MPP-AS programming. In patients with LVEDVI >Median , heart failure event rate increased following the 3-month randomization point with biventricular single-site pacing (0.0150±0.1725 in LVEDVI >Median versus −0.0190±0.0808 in LVEDVI ≤Median , P =0.012), but no heart failure event occurred in patients with MPP-AS programming between 3 and 9 months in LVEDVI >Median . All measured outcomes did not differ in patients receiving MPP-AS and biventricular single-site pacing with LVEDVI ≤Median .

Conclusions:

Conventional biventricular single-site pacing, even with a quadripolar lead, has reduced efficacy in patients with LV enlargement. However, the greatest response rate in patients with larger hearts was observed when programmed to MPP-AS pacing.

Should different ECG QRS duration criteria be used for men and women with heart failure for cardiac resynchronization therapy?

In the present paper we review data of the efficacy of CRT based on baseline QRS duration and morphology in patients with heart failure due to left ventricle systolic dysfunction. We specifically review data that analyzed men and women separately. The main findings suggest benefit of CRT in patients with baseline LBBB, but not in patients without LBBB. Benefit is directly related to QRS duration at baseline with increasing rates and magnitude of echocardiographic response (in terms of improvement in ejection fraction and decrease in LV size) and clinical response with increasing baseline QRS. The effect was most pronounced when QRSd was above 150 ms. Among women treated with CRT, similar to men, the benefit is also confined mainly to patients with baseline LBBB. In contrast to men benefit is evident starting with QRSd >130 ms. These findings may suggest that different QRS duration criteria should be used for men and women considered for CRT.

Differences in clinical characteristics and reported quality of life of men and women undergoing cardiac resynchronization therapy

Aims

Response to cardiac resynchronization therapy (CRT) is known to be associated with a number of clinical characteristics, including QRS duration and morphology, gender, height, and the aetiology of heart failure (HF). We assessed the relation of gender and baseline characteristics with QRS duration and Kansas City Cardiomyopathy Questionnaire.

Methods and results

AdaptResponse is a global randomized trial. The trial enrolled CRT‐indicated patients with New York Heart Association classes II–IV HF, left bundle branch block (QRS ≥ 140 ms in men, ≥130 ms in women), and baseline PR interval ≤200 ms. In total, 3620 patients were randomized, including 1569 women (43.3%) approaching the actual proportion of women in the HF population. Women were older and more often New York Heart Association class III or IV than men (55.6% vs. 48.7%), had less frequent ischaemic cardiomyopathy (21.2% vs. 39.5%), and had a 5.1 ms shorter QRS duration than men. Women were more often depressed (18.5% vs. 9.7%), had a significantly lower Kansas City Cardiomyopathy Questionnaire score, and had differences in medication prescriptions.

Conclusions

AdaptResponse is the largest randomized CRT trial and enrolled more women than any other landmark CRT trial. Women differed from men with regard to baseline characteristics and quality of life. Whether these differences translate into clinical outcome differences will be examined further in the AdaptResponse trial.

Sex differences in left ventricular electrical dyssynchrony and outcomes with cardiac resynchronization therapy

Background

Women seem to derive more benefit from cardiac resynchronization therapy (CRT) than men, even after accounting for the higher burden of risk factors for nonresponse often observed in men.

Objective

To assess for sex-specific differences in left ventricular (LV) electrical dyssynchrony as a contributing electrophysiological explanation for the greater degree of CRT benefit among women.

Methods

We compared the extent of baseline LV electrical dyssynchrony, as measured by the QRS area (QRSA), among men and women with left bundle branch block (LBBB) undergoing CRT at Duke University (n = 492, 35% women) overall and in relation to baseline QRS characteristics using independent sample t tests and Pearson correlation coefficients. Cox regression analyses were used to relate sex, QRSA, and QRS characteristics to the risk of cardiac transplantation, LV assist device implant, or death.

Results

Although the mean QRS duration (QRSd) did not differ by sex, QRSA was greater for women vs men (113.8 μVs vs 98.2 μVs, P < .001), owing to differences in the QRSd <150 ms subgroup (92.3 ± 28.7 μVs vs 67.6 ± 26.2 μVs, P < .001). Among those with nonstrict LBBB, mean QRSd was similar but QRSA was significantly greater among women than men (96.0 ± 25.0 μVs vs 63.6 ± 26.2 μVs, P < .001). QRSA was similar among men and women with strict LBBB (P = .533). Female sex was associated with better long-term outcomes in an unadjusted model (hazard ratio 0.623, confidence interval 0.454–0.857, P = .004) but sex no longer predicted outcomes after accounting for differences in QRSA.

Conclusions

Our study suggests that sex-specific differences in LV dyssynchrony contribute to greater CRT benefit among women. Standard QRSd and morphology assessments seem to underestimate the extent of LV electrical dyssynchrony among women with LBBB.

Sex Disparities in the Choice of Cardiac Resynchronization Therapy Device: An Analysis of Trends, Predictors, and Outcomes

BACKGROUND

There is limited evidence on the influence of sex on the decision to implant a cardiac resynchronization therapy device with pacemaker (CRT-P) or defibrillator (CRT-D) and the existence of sex-dependent differences in complications that may affect this decision.

METHODS

All patients undergoing de novo CRT implantation (2004-2014) in the United States National Inpatient Sample were included and stratified by device type (CRT-P and CRT-D). Multivariable logistic regression models were conducted to assess the association of female sex with receipt of CRT-D and periprocedural complications.

RESULTS

Out of 400,823 weighted CRT procedural records, the overall percentages of women undergoing CRT-P and CRT-D implantations were 41.5% and 27.8%, respectively, and these percentages increased compared with men over the study period. Women were less likely to receive CRT-D (odds ratio 0.66, 95% confidence interval 0.64-0.67), and this trend remained stable throughout the study period (P = 0.06). Furthermore, compared with men, women were associated with increased odds of procedure-related complications (bleeding, thoracic, and cardiac) in the CRT-D group but not in the CRT-P group. Factors such as atrial fibrillation, malignancies, renal failure, advanced age (> 60 years), and admission to nonurban/small hospitals favoured the receipt of CRT-P over CRT-D, whereas history of ischemic heart disease, cardiac arrest ,or ventricular arrhythmias favoured the receipt of CRT-D over CRT-P.

CONCLUSIONS

Women were associated with persistently reduced odds of receipt of CRT-D compared with men over an 11-year period. This study identifies important factors that predict the choice of CRT device offered to patients in the United States.

Sex Differences in Advanced Heart Failure Therapies

This in-depth review of sex differences in advanced heart failure therapy summarizes the existing literature on implantable cardioverter defibrillators, biventricular pacemakers, mechanical circulatory support, and transplantation with a focus on utilization, efficacy/clinical effectiveness, adverse events, and controversies. One will learn about the controversies regarding efficacy/clinical effectiveness of implantable cardioverter defibrillators and understand why these devices should be implanted in women even if there are sex differences in appropriate shocks. Individuals will learn about the sex differences with biventricular pacemakers with respect to ventricular remodeling and reduction in heart failure hospitalizations/mortality, as well as, possible mechanisms. We will demonstrate sex differences in heart transplantation and waitlist survival. Despite similar survival for women and men with left ventricular assist devices, there are sex differences in adverse events. These devices do successfully bridge women and men to transplant, yet women are less likely than men to have a left ventricular assist at time of listing and time of transplantation. Finally, one will learn about the concerns regarding poor outcome for men who receive female donor hearts and discover this may not be due to sex, but rather size. More research is needed to better understand sex differences and further improve advanced heart failure therapy for both women and men.

Sex-Dependent QRS Guidelines for Cardiac Resynchronization Therapy Using Computer Model Predictions

Cardiac resynchronization therapy (CRT) is an important treatment for heart failure. Low female enrollment in clinical trials means that current CRT guidelines may be biased toward males. However, females have higher response rates at lower QRS duration (QRSd) thresholds. Sex differences in the left ventricle (LV) size could provide an explanation for the improved female response at lower QRSd. We aimed to test if sex differences in CRT response at lower QRSd thresholds are explained by differences in LV size and hence predict sex-specific guidelines for CRT. We investigated the effect that LV size sex difference has on QRSd between male and females in 1093 healthy individuals and 50 CRT patients using electrophysiological computer models of the heart. Simulations on the healthy mean shape models show that LV size sex difference can account for 50–100% of the sex difference in baseline QRSd in healthy individuals. In the CRT patient cohort, model simulations predicted female-specific guidelines for CRT, which were 9–13 ms lower than current guidelines. Sex differences in the LV size are able to account for a significant proportion of the sex difference in QRSd and provide a mechanistic explanation for the sex difference in CRT response. Simulations accounting for the smaller LV size in female CRT patients predict 9–13 ms lower QRSd thresholds for female CRT guidelines.

Sex-specific clinical outcomes after cardiac resynchronization therapy in left bundle branch block-associated idiopathic nonischemic cardiomyopathy: A NEOLITH II substudy

BACKGROUND

Sex differences in clinical outcomes for left bundle branch block (LBBB)-associated idiopathic nonischemic cardiomyopathy (NICM) after cardiac resynchronization therapy (CRT) are not well described.

METHODS

A retrospective cohort study at an academic medical center included subjects with LBBB-associated idiopathic NICM who received CRT. Cox regression analyses estimated the hazard ratios (HRs) between sex and clinical outcomes.

RESULTS

In 123 total subjects (mean age 62 years, mean initial left ventricular ejection fraction 22.8%, 76% New York Heart Association class III, and 98% CRT-defibrillators), 55 (45%) were men and 68 (55%) were women. The median follow-up time after CRT was 72.4 months. Similar risk for adverse clinical events (heart failure hospitalization, appropriate implantable cardioverter-defibrillator shock, appropriate antitachycardia pacing therapy, ventricular assist device implantation, heart transplantation, and death) was observed between men and women (HR, 1.20; 95% confidence interval [CI] 0.57-2.51; p = 0.63). This persisted in multivariable analyses. Men and women had similar risk for all-cause mortality in univariable analysis, but men had higher risk in the final multivariable model that adjusted for age at diagnosis, QRS duration, and left ventricular end-diastolic dimension index (HR, 4.55; 95% CI, 1.26-16.39; p = 0.02). The estimated 5-year mortality was 9.5% for men and 6.9% for women.

CONCLUSIONS

In LBBB-associated idiopathic NICM, men have higher risk for all-cause mortality after CRT when compared to women.

Sex Differences in the Management of Advanced Heart Failure

PURPOSE OF REVIEW

Heart failure (HF) is prevalent among women and remains a leading cause of morbidity and mortality in the United States. Currently, 3 million women live with HF and the prevalence is projected to continue to increase. The purpose of this review is to highlight sex differences in the use and response to evidence-based pharmacological, device, and advanced HF therapies, as well as explore emerging areas of research in sex differences in the treatment of HF.

RECENT FINDINGS

Under-representation of women in clinical HF trials has limited our understanding of sex-related differences in the treatment and outcomes of HF. Important sex differences exist in the use of evidence-based HF therapies and clinical response among women with HF. In general, women tend to obtain the same clinical benefit from evidence-based HF drug and device therapies, but the utilization rates of guideline-directed medical therapies remain poor compared to men. Future research efforts should focus on increasing the enrollment of women in HF trials to help gain helpful insight into sex-specific differences in treatment effects and subsequent clinical outcomes.

Interaction of Left Ventricular Size and Sex on Outcome of Cardiac Resynchronization Therapy Among Patients With a Narrow QRS Duration in the EchoCRT Trial

BACKGROUND

Longer QRS duration (QRSd) improves, but increased left ventricular (LV) end-diastolic volume (LVEDV) reduces, efficacy of cardiac resynchronization therapy (CRT). QRSd/LVEDV ratios differ between sexes. We hypothesized that in the EchoCRT (Echocardiography Guided Cardiac Resynchronization Therapy) trial enrolling patients with heart failure with QRSd <130 ms, those with larger LVEDV would deteriorate but those with the highest QRSd/LVEDV would improve with CRT.

METHODS AND RESULTS

Primary outcome in patients (n=787, 72% men, 93% New York Heart Association class III, QRSd <130 ms, LV ejection fraction ≤35%, LV dilation and dyssynchrony) randomized to CRT-ON or CRT-OFF and followed up for 19 months was compared according to LVEDV (height indexed) or QRSd/LVEDV ratio, in multivariable analysis. Structural remodeling was assessed echocardiographically 6 months after implantation. Patients with baseline LVEDV higher than or equal to median worsened with CRT (death/heart failure hospitalization: CRT-ON versus CRT-OFF, 35.2% versus 24.5% [hazard ratio, 1.64; 95% confidence interval, 1.11-2.42; P=0.012]), but those with LVEDV lower than median remained unaffected. Patients with the highest QRSd/LVEDV ratio improved with CRT (death/heart failure hospitalization in top quartile: 20.9% in CRT-ON [n=91] versus 28.3% in CRT-OFF [n=106] [hazard ratio, 0.64; 95% confidence interval, 0.34-1.24; P=0.188], versus the remaining quartiles: 31.7% in CRT-ON [n=300] versus 24.8% in CRT-OFF [n=290] [hazard ratio, 1.47; 95% confidence interval, 1.07-2.02; P=0.016], test for interaction P=0.046). QRSd and dyssynchrony were similar between groups. The 3-way test for interaction indicated no sex-specific effects. However, numerically, men with LVEDV higher than or equal to median accounted for worse outcomes of CRT-ON. Women, with the highest QRSd/LVEDV ratio exhibited significant reverse remodeling.

CONCLUSION

CRT has opposite effects among patients with heart failure with QRSd <130 ms according to LV size: worsening outcomes in patients with larger LV, but inducing beneficial effects in those with smaller LV.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT00683696.

Programming Cardiac Resynchronization Therapy for Electrical Synchrony: Reaching Beyond Left Bundle Branch Block and Left Ventricular Activation Delay

BACKGROUND

QRS narrowing following cardiac resynchronization therapy with biventricular (BiV) or left ventricular (LV) pacing is likely affected by patient-specific conduction characteristics (PR, qLV, LV-paced propagation interval), making a universal programming strategy likely ineffective. We tested these factors using a novel, device-based algorithm (SyncAV) that automatically adjusts paced atrioventricular delay (default or programmable offset) according to intrinsic atrioventricular conduction.

METHODS AND RESULTS

Seventy-five patients undergoing cardiac resynchronization therapy (age 66±11 years; 65% male; 32% with ischemic cardiomyopathy; LV ejection fraction 28±8%; QRS duration 162±16 ms) with intact atrioventricular conduction (PR interval 194±34, range 128-300 ms), left bundle branch block, and optimized LV lead position were studied at implant. QRS duration (QRSd) reduction was compared for the following pacing configurations: nominal simultaneous BiV (Mode I: paced/sensed atrioventricular delay=140/110 ms), BiV+SyncAV with 50 ms offset (Mode II), BiV+SyncAV with offset that minimized QRSd (Mode III), or LV-only pacing+SyncAV with 50 ms offset (Mode IV). The intrinsic QRSd (162±16 ms) was reduced to 142±17 ms (-11.8%) by Mode I, 136±14 ms (-15.6%) by Mode IV, and 132±13 ms (-17.8%) by Mode II. Mode III yielded the shortest overall QRSd (123±12 ms, -23.9% [P<0.001 versus all modes]) and was the only configuration without QRSd prolongation in any patient. QRS narrowing occurred regardless of QRSd, PR, or LV-paced intervals, or underlying ischemic disease.

CONCLUSIONS

Post-implant electrical optimization in already well-selected patients with left bundle branch block and optimized LV lead position is facilitated by patient-tailored BiV pacing adjusted to intrinsic atrioventricular timing using an automatic device-based algorithm.

Survival in Women Versus Men Following Implantation of Pacemakers, Defibrillators, and Cardiac Resynchronization Therapy Devices in a Large, Nationwide Cohort

Background

Whether outcomes differ between sexes following treatment with pacemakers (PM), implantable cardioverter defibrillators, and cardiac resynchronization therapy (CRT) devices is unclear.

Methods and Results

Consecutive US patients with newly implanted PM, implantable cardioverter defibrillators, and CRT devices from a large remote monitoring database between 2008 and 2011 were included in this observational cohort study. Sex‐specific all‐cause survival postimplant was compared within each device type using a multivariable Cox proportional hazards model, stratified on age and adjusted for remote monitoring utilization and ZIP‐based socioeconomic variables. A total of 269 471 patients were assessed over a median 2.9 [interquartile range, 2.2, 3.6] years. Unadjusted mortality rates (MR; deaths/100 000 patient‐years) were similar between women versus men receiving PMs (n=115 076, 55% male; MR 4193 versus MR 4256, respectively; adjusted hazard ratio, 0.87; 95% CI, 0.84–0.90; P<0.001) and implantable cardioverter defibrillators (n=85 014, 74% male; MR 4417 versus MR 4479, respectively; adjusted hazard ratio, 0.98; 95% CI, 0.93–1.02; P=0.244). In contrast, survival was superior in women receiving CRT defibrillators (n=61 475, 72% male; MR 5270 versus male MR 7175; adjusted hazard ratio, 0.73; 95% CI, 0.70–0.76; P<0.001) and also CRT pacemakers (n=7906, 57% male; MR 5383 versus male MR 7625, adjusted hazard ratio, 0.69; 95% CI, 0.61–0.78; P<0.001). This relative difference increased with time. These results were unaffected by age or remote monitoring utilization.

Conclusions

Women accounted for less than 30% of high‐voltage implants and fewer than half of low‐voltage implants in a large, nation‐wide cohort. Survival for women and men receiving implantable cardioverter defibrillators and PMs was similar, but dramatically greater for women receiving both defibrillator‐ and PM‐based CRT.