The impact of left ventricular size on response to cardiac resynchronization therapy

Case Studies of Cardiac Resynchronization Therapy "Nonresponders"

Outcomes following cardiac resynchronization therapy (CRT) vary widely, with some patients experiencing normalization of left ventricular function to some who seem to be harmed by biventricular pacing. The care of CRT patients postoperatively is complex and requires input from physicians specializing in electrophysiology, heart failure, and often cardiac imaging. In this section, cases of apparent CRT suboptimal response from a dedicated CRT optimization clinic are presented.

Progression of cardiac disease in patients with lamin A/C mutations

Aims

We aimed to study the progression of cardiac dysfunction in patients with lamin A/C mutations and explore markers of adverse cardiac outcome.

Methods and results

We followed consecutive lamin A/C genotype-positive patients divided into tertiles according to age. Patients underwent repeated clinical examinations, electrocardiograms (ECGs), and echocardiograms. We followed left ventricular (LV) and right ventricular (RV) size and function, and the severity atrioventricular-valve regurgitations. Outcome was death, LVAD implant, or cardiac transplantation. We included 101 patients [age 44 (29–54) years, 39% probands, 50% female]. We analysed 576 echocardiograms and 258 ECGs during a follow-up of 4.9 (interquartile range 2.5–8.2) years. The PR-interval increased at young age from 204 ± 73 to 212 ± 69 ms (P < 0.001), LV ejection fraction (LVEF) declined from middle age from 50 ± 12% to 47 ± 13% (P < 0.001), while LV volumes remained unchanged. RV function and tricuspid regurgitation worsened from middle age with accelerating rates. Progression of RV dysfunction [odds ratio (OR) 1.3, 95% confidence interval (CI) (1.03–1.65), P = 0.03] and tricuspid regurgitation [OR 4.9, 95% CI (1.64–14.9), P = 0.004] were associated with outcome when adjusted for age, sex, comorbidities, LVEF, and New York Heart Association functional class.

Conclusion

In patients with lamin A/C genotype, electrical disease started at young age. From middle age, LV function deteriorated progressively, while LV size remained unchanged. Worsening of RV function and tricuspid regurgitation accelerated in older age and were associated with outcome. Our systematic map on cardiac deterioration may help optimal monitoring and prognostication in lamin A/C disease.

A new method to recommend left ventricular lead positions for improved CRT volumetric response and long-term prognosis

OBJECTIVES

Using ECG-gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), we sought to develop and validate a new method to recommend left ventricular (LV) lead positions in order to improve volumetric response and long-term prognosis after cardiac resynchronization therapy (CRT).

METHODS

Seventy-nine patients received gated SPECT MPI at baseline, and echocardiography at baseline and follow-up. The volumetric response referred to a reduction of ≥ 15% in LV end-systolic volume 6 months after CRT. After excluding apical, septal, and scarred segments, there were three levels of recommended segments: (1) the optimal recommendation: the latest contracting viable segment; (2) the 2nd recommendation: the late contracting viable segments whose contraction delays were within 10° of the optimal recommendation; and (3) the 3rd recommendation: the viable segments adjacent to the optimal recommendation when there was no late contracting viable segment.

RESULTS

After excluding 11 patients whose LV lead was placed in apical or scarred segments, 75.6% of the patients concordant to recommended LV segments (n = 41) responded to CRT while 51.9% of those with non-recommended LV lead locations (n = 27) were responders (P = .043). Response rates were 76.9%, 76.9% , and 73.3% (P = .967), respectively, when LV lead was implanted in the optimal recommendation (n = 13), the 2nd recommendation (n = 13), and the 3rd recommendation (n = 15). LV leads placed at recommended segments reduced composite events of all-cause mortality or heart failure (HF) rehospitalization compared with pacing at non-recommended segments (log-rank χ2 = 5.623, P = .018).

CONCLUSIONS

Pacing in the recommended LV lead segments identified on gated SPECT MPI was associated with improved volumetric response to CRT and long-term prognosis.

Cardiac Resynchronization Therapy in Non-Ischemic Cardiomyopathy: Role of Multimodality Imaging

Non-ischemic cardiomyopathy encompasses a heterogeneous group of diseases, with a generally unfavorable long-term prognosis. Cardiac resynchronization therapy (CRT) is a useful therapeutic option for patients with symptomatic heart failure, currently recommended by all available guidelines, with outstanding benefits, especially in non-ischemic dilated cardiomyopathy. Still, in spite of clear indications based on identifying a dyssynchronous pattern on the electrocardiogram (ECG,) a great proportion of patients are non-responders. The idea that multimodality cardiac imaging can play a role in refining the selection criteria and the implant technique and help with subsequent system optimization is promising. In this regard, predictors of CRT response, such as apical rocking and septal flash have been identified. Promising new data come from studies using cardiac magnetic resonance and nuclear imaging for showcasing myocardial dyssynchrony. Still, to date, no single imaging predictor has been included in the guidelines, probably due to lack of validation in large, multicenter cohorts. This review provides an up-to-date synthesis of the latest evidence of CRT use in non-ischemic cardiomyopathy and highlights the potential additional value of multimodality imaging for improving CRT response in this population. By incorporating all these findings into our clinical practice, we can aim toward obtaining a higher proportion of responders and improve the success rate of CRT.

Long-Term Outcomes in Patients With a Left Ejection Fraction ≤15% Undergoing Cardiac Resynchronization Therapy

OBJECTIVES

This study aimed to determine the long-term outcomes and predictors of left ventricular (LV) ejection fraction (LVEF) improvement in patients with severe cardiomyopathies undergoing cardiac resynchronization therapy (CRT).

BACKGROUND

Whether patients with severe LV dysfunction benefit from CRT or have reached a point in disease severity past the point at which CRT is beneficial is unknown.

METHODS

We collected clinical and echocardiographic data on 420 patients with an LVEF of ≤15% and a QRS duration of ≥120 ms undergoing CRT at the Cleveland Clinic and 2 hospitals in the Johns Hopkins Health System between April 2003 and May 2014. Multivariate models were created to determine factors associated with response to CRT, defined as an absolute improvement in LVEF of >5% and survival free of LVAD and heart transplant. Procedure-related deaths were also collected.

RESULTS

A total of 298 patients had pre- and appropriately timed post-CRT echocardiograms, of whom 145 (48.7%) met the criteria for response. In multivariate analysis, LV size and left bundle branch block (LBBB) were associated with response. Among the most dilated quintile (LV end-diastolic diameter [LVEDD] of >7.8 cm), 30.4% met the criteria for response. In multivariate analysis, smaller LV end-diastolic dysfunction and presence of LBBB were associated with improved survival free of heart failure and LVAD over a mean follow-up period of 5.2 years. There were no procedure-related deaths.

CONCLUSIONS

Patients with severe LV dysfunction respond to CRT, although at a lower rate compared to traditional CRT candidates. Smaller LV size and LBBB are important predictors of positive outcomes in this population. Even among the most dilated patients, 30.4% realized a meaningful improvement in LVEF with CRT. The CRT implant procedure itself appears well tolerated.

Left ventricular dimensions predict risk of appropriate shocks but not mortality in cardiac resynchronization therapy-defibrillator recipients with left bundle-branch block and non-ischemic cardiomyopathy

Aims

Patients with non-ischaemic cardiomyopathy (NICM) and left bundle-branch block (LBBB) often benefit markedly from cardiac resynchronization therapy (CRT). Cardiac resynchronization therapy responders have a lower risk of appropriate device shocks from CRT-defibrillators (CRT-D) than do non-responders. Larger baseline left ventricular (LV) dimensions may be associated with less CRT response and thus greater risk of appropriate shocks.

Methods and results

We analysed all (n = 249; 55% female) primary prevention CRT-D recipients at our institution with LBBB, NICM, and measured LV dimensions prior to device implant for the outcomes of (i) appropriate shocks, (ii) any appropriate tachyarrhythmia therapies, and (iii) risk of death, transplant, or left ventricular assist device (LVAD). During 59 months (interquartile range 21.5-91.5) follow-up, 19 (8%) patients received ≥1 appropriate shock, and 67 (27%) patients died, received a transplant, or required LVAD. Receiver-operating characteristic analysis of LV end-diastolic diameter (LVEDD) per meter height vs. appropriate shock(s) revealed an area under the curve of 0.75 (95% CI 0.65-0.85; P < 0.001). No patient with indexed LVEDD <3.36 cm/m (n = 76) received a shock. There was no statistically significant difference in risk of death, transplant, or LVAD (corrected HR 1.67, 95% CI 0.90-3.03; P = 0.103) in patients with indexed LVEDD above this cut-off compared to those with smaller dimension. Among 102 patients with paired quantitative echocardiograms, there was no difference in LVEF change between patients with indexed LVEDD <3.36 cm/m (n = 27; median 11%) and larger (n = 75; median 14%).

Conclusion

Patients with LVEDD <3.36 cm/m height prior to CRT-D implant in the setting of NICM and LBBB have minimal risk of appropriate shocks but similar risk of death, transplant- and LVAD and similar extent of LV functional improvement as patients with larger LVEDD. CRT-pacemakers may be appropriate in such patients.

Sex-specific mortality differences in heart failure patients with ischemia receiving cardiac resynchronization therapy

Background

Recent studies have reported prognosis differences between male and female heart failure patients following cardiac resynchronization therapy (CRT). However, the potential clinical factors that underpin these differences remain to be elucidated.

Methods

A meta-analysis was performed to investigate the factors that characterize sex-specific differences following CRT. This analysis involved searching the Medline (Pubmed source) and Embase databases in the period from January 1980 to September 2016.

Results

Fifty-eight studies involving 33445 patients (23.08% of whom were women) were analyzed as part of this study. Only patients receiving CRT with follow-up greater than six months were included in our analysis. Compared with males, females exhibited a reduction of 33% (hazard ratio, 0.67; 95% confidence interval, 0.62–0.73; P < 0.0001) and 42% (hazard ratio, 0.58; 95% confidence interval, 0.46–0.74; P = 0.003) in all-cause mortality and heart failure hospitalization or heart failure, respectively. Following a stratified analysis of all-cause mortality, we observed that ischemic causes (p = 0.03) were likely to account for most of the sex-specific differences in relation to CRT.

Conclusion

These data suggest that women have a reduced risk of all-cause mortality and heart failure hospitalization or heart failure following CRT. Based on the results from the stratified analysis, we observed more optimal outcomes for females with ischemic heart disease. Thus, ischemia are likely to play a role in sex-related differences associated with CRT in heart failure patients. Further studies are required to determine other indications and the potential mechanisms that might be associated with sex-specific CRT outcomes.

Predictors of response to cardiac resynchronization therapy: A prospective cohort study

INTRODUCTION

Cardiac resynchronization therapy (CRT) has modified the prognosis of chronic heart failure (HF) with left ventricular systolic dysfunction. However, 30% of patients do not have a favorable response. The big question is how to determine predictors of response.

AIMS

To identify baseline characteristics that might influence echocardiographic response to CRT.

METHODS AND RESULTS

We performed a prospective single-center hospital-based cohort study of consecutive HF patients selected to CRT (NYHA class II-IV, left ventricular ejection fraction (LVEF) <35% and QRS complex ≥120 ms). Responders were defined as those with a ≥5% absolute increase in LVEF at six months. Clinical, electrocardiographic, laboratory, echocardiographic, autonomic, endothelial and cardiopulmonary function parameters were assessed before CRT device implantation. Logistic regression models were used. Seventy-nine patients were included, 54 male (68.4%), age 68.1 years (standard deviation 10.2), 19 with ischemic etiology (24%). At six months, 51 patients (64.6%) were considered responders. Although by univariate analysis baseline tricuspid annular plane systolic excursion (TAPSE) and serum creatinine were significantly different in responders, on multivariate analysis only TAPSE was independently associated with response, with higher values predicting a positive response to CRT (OR=1.13; 95% CI: 1.02-1.26; p=0.020). TAPSE ≥15 mm was strongly associated with response, and TAPSE <15 mm with non-response (p=0.005). Responders had no TAPSE values below 10 mm.

CONCLUSION

From a range of clinical and technical baseline characteristics, multivariate analysis only identified TAPSE as an independent predictor of CRT response, with TAPSE <15 mm associated with non-response. This study highlights the importance of right ventricular dysfunction in CRT response. ClinicalTrials.gov identifier: NCT02413151.

Left Ventricular Size does not Modify the Effect of QRS Duration in Predicting Response to Cardiac Resynchronization Therapy

BACKGROUND

QRS duration (QRSd) may be impacted by both left ventricular (LV) dilatation and conduction delay. It is possible therefore that the same QRSd may portend significantly different amounts of LV activation delay in patients with small versus large left ventricles. We hypothesized that LV size modifies the effect of QRSd on predicting outcomes in patients undergoing CRT implant.

METHODS

We extracted data on consecutive patients presenting for initial CRT implant. In patients with a follow-up echocardiogram, response was defined as an absolute improvement in LV ejection fraction ≥5%. Multivariate models were created to determine if left ventricular end-diastolic diameter (LVEDD) modified the effect of QRSd on its association with both long-term survival free of left ventricular assist device (LVAD) and heart transplant and echocardiographic response.

RESULTS

464 patients met inclusion criteria. At a mean follow-up of 4.9 ± 2.6 years, there were 210 deaths, 13 heart transplants, and 12 LVAD placements. There was a weak but significant correlation between baseline QRSd and LVEDD (Spearman's Rho 0.106, P < 0.001). In a multivariate analysis, there was no evidence of effect modification of LVEDD on QRSd (LVEDDi*QRS interaction term HR 1.0 [0.995-1.006], P = 0.94). Note that 305 patients had a follow-up echocardiogram, of whom 193 met the criteria for response. In a multivariate analysis, there was no evidence of effect modification of LVEDD on QRSd (LVEDDi*QRS interaction term odds ratio 0.998 (0.988-1.008), P = 0.65).

CONCLUSION

LV size does not modify the effect of QRSd and its association with outcomes following CRT. The correlation between LV size and QRSd in patients with a QRSd ≥ 120 ms is weak.

T-wave area as biomarker of clinical response to cardiac resynchronization therapy

AIMS

There is increasing evidence that left bundle branch block (LBBB) morphology on the electrocardiogram is a positive predictor for response to cardiac resynchronization therapy (CRT). We previously demonstrated that the vectorcardiography (VCG)-derived T-wave area predicts echocardiographic CRT response in LBBB patients. In the present study, we investigate whether the T-wave area also predicts long-term clinical outcome to CRT.

METHODS AND RESULTS

This is a retrospective study consisting of 335 CRT recipients. Primary endpoint were the composite of heart failure (HF) hospitalization, heart transplantation, left ventricular assist device implantation or death during a 3-year follow-up period. HF hospitalization and death alone were secondary endpoints. The patient subgroup with a large T-wave area and LBBB 36% reached the primary endpoint, which was considerably less (P < 0.01) than for patients with LBBB and a small T-wave area or non-LBBB patients with a small or large T-wave area (48, 57, and 51%, respectively). Similar differences were observed for the secondary endpoints, HF hospitalization (31 vs. 51, 51, and 38%, respectively, P < 0.01) and death (19 vs. 42, 34, and 42%, respectively, P < 0.01). In multivariate analysis, a large T-wave area and LBBB were the only independent predictors of the combined endpoint besides high creatinine levels and use of diuretics.

CONCLUSION

T-wave area may be useful as an additional biomarker to stratify CRT candidates and improve selection of those most likely to benefit from CRT. A large T-wave area may derive its predictive value from reflecting good intrinsic myocardial properties and a substrate for CRT.

ECG Patterns In Cardiac Resynchronization Therapy

Cardiac resynchronization therapy is an established treatment modality in heart failure. Though non-response is a serious issue. To address this issue, a good understanding of the electrical activation during underlying intrinsic ventricular activation, biventricular as well as right- and left ventricular pacing is needed. By interpreting the 12-lead electrocardiogram, possible reasons for suboptimal treatment can be identified and addressed. This article reviews the literature on QRS morphology in cardiac resynchronization therapy and its role in optimization of therapy.

More Favorable Response to Cardiac Resynchronization Therapy in Women Than in Men

Background—

Data on sex difference in response to cardiac resynchronization therapy (CRT) remain controversial. We conducted a meta-analysis to summarize all published studies to determine whether sex-based differences in response to CRT exist.

Methods and Results—

We performed a literature search using MEDLINE (source PubMed; January 1966 to March 2014) and EMBASE (January 1980 to March 2014) with no restrictions. Pooled effect estimates were obtained by using random-effects meta-analysis. Seventy-two studies involving 33 434 patients were identified. Overall, female patients had better outcomes from CRT compared with male patients, with a significant 33% reduction in the risk of death from any cause (hazard ratio, 0.67; 95% confidence interval, 0.61–0.74; P <0.001), 20% reduction in death or hospitalization for heart failure (hazard ratio, 0.80; 95% confidence interval, 0.71–0.90; P <0.001), 41% reduction in cardiac death (hazard ratio, 0.59; 95% confidence interval, 0.42–0.84; P <0.001), and 41% reduction in ventricular arrhythmias or sudden cardiac death (hazard ratio, 0.59; 95% confidence interval, 0.49–0.70; P <0.001). These more favorable responses to CRT in women were consistently associated with greater echocardiographic evidence of reverse cardiac remodeling in women than in men.

Conclusions—

Women obtained greater reductions in the risk of death from any cause, cardiac cause, death or hospitalization for heart failure, and ventricular arrhythmias or sudden cardiac death with CRT therapy compared with men, with consistently greater echocardiographic evidence of reverse cardiac remodeling in women than in men. Further studies are needed to investigate the exact reasons for these results and determine whether indications for CRT in women should be different from men.

Predictors for cardiac resynchronization therapy response: the importance of QRS morphology and left ventricular lead position

Although cardiac resynchronization therapy (CRT) is a well-established treatment for a subset of patients with chronic heart failure, a considerable proportion of eligible patients still fail to benefit from this treatment. The aim of this study was to identify potential independent predictors for being a responder to CRT. A single-center, retrospective analysis was conducted in 193 consecutive patients with heart failure and wide QRS complex who successfully underwent CRT device implantation from January 2006 to October 2012. Clinical characteristics, left ventricular lead position (LV-Ps), electrocardiography and echocardiography were evaluated before and 12 months after CRT. Response to CRT was defined as an absolute increase of ≥ 5% in left ventricular ejection fraction (LVEF) compared with baseline at 12 months after CRT implantation without heart failure rehospitalization or any cause of death. There were 132 responders (68%) and 61 nonresponders (32%). By univariate logistic analysis, the presence of non-left bundle branch block (non-LBBB) and QRS duration, chronic atrial fibrillation (AF), history of ventricular tachycardia (VT), degree of tricuspid regurgitation and left atrium dimension (LAD) at baseline, ΔQRS duration, and LV-Ps were associated with predicting a response to CRT. However, on multivariate analysis, only optimal LV-Ps and presence of non-LBBB remained independently predictive for a CRT response, with an odds ratio of 2.53 (95% confidence interval [CI]: 1.13-5.66, P = 0.023), 0.15(95% CI: 0.05-0.45, P = 0.001), respectively. Kaplan-Meier analysis revealed that patients with nonoptimal LV-Ps or non-LBBB morphology had a significantly higher rate of mortality or heart failure rehospitalization as compared with those with optimal LV-Ps or LBBB morphology (P < 0.05).

Characteristics of responders to cardiac resynchronization therapy: the impact of echocardiographic left ventricular volume

BACKGROUND

One-third of patients who receive cardiac resynchronization therapy (CRT) are classified as nonresponders. Characteristics of responders to CRT have been studied in multiple clinical trials.

HYPOTHESIS

Independent predictors of CRT response may be identified by studying a series of patients in routine clinical practice.

METHOD

One hundred twenty-five patients were examined retrospectively from a multidisciplinary CRT clinic program. Echocardiographic CRT response was defined as a decrease in left ventricular (LV) end-systolic volume of ≥15% and/or absolute increase of 5% in LV ejection fraction at the 6-month visit.

RESULTS

There were 81 responders and 44 nonresponders. By univariate analyses, female sex, nonischemic cardiomyopathy etiology, baseline QRS duration, the presence of left bundle branch block (LBBB), and left ventricular end-diastolic volume (LVEDV) index predicted CRT response. However, multivariate analysis demonstrated that only QRS duration, LBBB, and LVEDV index were independent predictors (QRS width, odds ratio [OR]: 1.027, 95% confidence interval [CI]: 1.004-1.050, P = 0.023; LBBB, OR: 3.568, 95% CI: 1.284-9.910, P = 0.015; LVEDV index, OR: 0.970, 95% CI: 0.953-0.987, P = 0.001). Although female sex and nonischemic etiology were associated with an improved CRT response on univariate analyses, after adjusting for LV volumes they were not independent predictors.

CONCLUSIONS

QRS width, LBBB, and LVEDV index are independent predictors for echocardiographic CRT response. Previously reported differences in CRT response for sex and cardiomyopathy etiology are associated with differences in baseline LV volumes in our clinical practice.