Four-Year Efficacy of Cardiac Resynchronization Therapy on Exercise Tolerance and Disease Progression

Electrical storm in patients with biventricular implantable cardioverter defibrillator: incidence, predictors, and prognostic implications

BACKGROUND

The aim of the present study was to evaluate the incidence, predictors, and related outcomes of patients with heart failure (HF) treated with cardiac resynchronization therapy with an implantable cardioverter defibrillator (CRT-D) who experienced electrical storm (ES). Electrical storm was defined as the occurrence of >or=3 episodes in 24 hours of sustained ventricular tachyarrhythmias.

METHODS

A total of 631 patients with HF (90% male, mean 66+/-9 years) consecutively received a CRT-D device. At baseline, the mean left ventricular ejection fraction was 26%+/-7%, the QRS duration was 164+/-33 milliseconds, and the mean New York Heart Association class was 3.3+/-0.3.

RESULTS

During a mean follow-up of 19+/-11 months, 2,419 ventricular tachyarrhythmia episodes were appropriately detected in 141 (22%) patients. Electrical storm occurred in 45 (7%) of 631 patients. Kaplan-Meier analysis and multivariable Cox regression showed that ES is more frequent in secondary prevention (hazard ratio 2.3, 95% CI 1.2-4.3, P=.015) and in nonischemic patients (hazard ratio 2.0, 95% CI 1.1-3.8, P=.028). In patients who presented ES, CRT was associated with only marginal nonsignificant improvements of New York Heart Association class and left ventricular ejection fraction. Hospitalizations and death due to HF were more frequent in patients with ES compared with those without ES, amounting to 16.8 (4.3) versus 8.6 (0.9) per 100 patient-years (P = .018) and 7.7 versus 2.7 per 100 patient-years (P=.014), respectively.

CONCLUSIONS

Electrical storm affect only 7% of CRT-D recipients and occurred more frequently in nonischemic patients with HF with biventricular implantable cardioverter defibrillators implanted for secondary prevention. Electrical storm was associated with worse HF morbidity and mortality.

Efficacy of LOw-dose DObutamine stress-echocardiography to predict cardiac resynchronization therapy response (LODO-CRT) multicenter prospective study: design and rationale

BACKGROUND

Although cardiac resynchronization therapy (CRT) has a well-demonstrated therapeutic effect in selected patients with advanced heart failure on optimized drug therapy, nonresponder rate remains high. The LODO-CRT is designed to improve patient selection for CRT. Design and rationale of this study are presented herein.

METHODS

LODO-CRT is a multicenter prospective study, started in late 2006, that enrolls patients with conventional indications for CRT (symptomatic stable New York Heart Association class III-IV on optimized drug therapy, QRS > or =120 milliseconds, left ventricular [LV] dilatation, LV ejection fraction < or =35%). This study is designed to assess the predictive value of LV contractile reserve (LVCR), determined through dobutamine stress echocardiography (defined as an LV ejection fraction increase >5 units), in predicting CRT response during follow-up. Assessment of CRT effects will follow 2 sequential phases: in phase 1, CRT response end point is defined as LV end-systolic volume reduction > or =10% at 6 months; in phase 2, both LV end-systolic volume reduction and clinical status via a clinical composite score will be evaluated at 12 months follow-up. Predictive value of LVCR will be compared to other measures, such as LV dyssynchrony measures, through adjusted multivariable analysis. For the purpose of the study, target patient number is 270 (with 95% confidence, 80% power, alpha < or = .05). Enrollment should be complete by the end of 2008.

CONCLUSIONS

The LODO-CRT trial is testing the hypothesis that LVCR assessment, using low-dose dobutamine stress echocardiography test, should effectively predict positive response to CRT both in terms of the reverse remodeling process as well as favorable long-term clinical outcome. Moreover, the predictive value of LVCR will be compared to that of conventional intra-LV dyssynchrony measures.

The place of hybrid therapies with drugs to supplement nonpharmacological therapies in atrial fibrillation

Atrial fibrillation (AF) is one of the most common cardiac arrhythmias, and its prevalence continues to rise as the aged population increases. Comparative studies of rhythm control and rate control have been equivocal; however, the benefits of rhythm control may have been offset by the limitations of antiarrhythmic drugs. More recently, nonpharmacological therapies have emerged that provide hope of more effective rhythm control. Catheter ablation techniques have gained favour with high success rates in specialized centers, although these techniques are not without complications and require considerable expertise. Pacing therapies designed to reduce harmful right ventricular pacing and increase physiological pacing have shown benefit in AF patients with bradycardia. Despite this progress, no single modality confers benefit for all patients. Strategies to combine these treatment modalities in a hybrid approach has shown increasing promise for subgroups of AF patients.

Atrial fibrillation in recipients of cardiac resynchronization therapy device: 1-year results of the randomized MASCOT trial

BACKGROUND

Atrial fibrillation (AF) is associated with increased morbidity and mortality in patients suffering from heart failure (HF). Patients in New York Heart Association HF classes III or IV, with systolic dysfunction and a wide QRS, are candidates for cardiac resynchronization therapy (CRT), and might benefit from atrial overdrive pacing (AOP).

METHODS

The Management of Atrial fibrillation Suppression in AF-HF COmorbidity Therapy (MASCOT) trial enrolled 409 CRT device recipients (79% men), who were randomly assigned to AOP ON (n = 197), versus AOP OFF (n = 197) and followed up for 1 year. Their mean age was 68 +/- 10 years, left ventricular ejection fraction 25 +/- 6%, QRS duration 163 +/- 29 milliseconds. New York Heart Association class III was present in 86% of patients and 19% had a history of paroxysmal AF. The primary study end point was incidence of permanent AF at 1 year.

RESULTS

Atrial overdrive pacing increased the percentage of atrial pacing from 30% to 80% (P < .0001), was well tolerated, and did not interfere with (a) delivery of CRT (95% mean ventricular pacing in both groups), (b) response to CRT (70% responders in the control vs 67% in the treatment group), or (c) cardiac function (left ventricular ejection fraction increased from 24.5% +/- 6.2% to 32.7% +/- 10.9% in the control and from 25.8% +/- 6.8% to 33.1% +/- 12.6% in the treatment group). The incidence of permanent AF was 3.3% in both groups. By logistic regression analysis, a history of AF (P < .001) and absence of antiarrhythmic drugs (P = .002) were associated with permanent AF.

CONCLUSIONS

In this first trial of a specific AF prevention algorithm in CRT recipients, AOP was safe and did not worsen HF. The prevention algorithm did not lower the 1-year incidence of AF.

Comparison of benefits and mortality in cardiac resynchronization therapy in patients with atrial fibrillation versus patients in sinus rhythm (Results of the Spanish Atrial Fibrillation and Resynchronization [SPARE] Study)

The efficacy of cardiac resynchronization therapy (CRT) in patients with atrial fibrillation (AF) and the need for atrioventricular junction ablation in these patients is controversial. The aim of the study was to analyze CRT results in patients with permanent AF. A total of 470 consecutive patients who underwent CRT in 6 centers were included in this study. Of these patients, 126 (27%) had permanent AF. Patients were evaluated at baseline and 12 months. No difference was found in the magnitude of improvement experienced by patients with AF compared with those in sinus rhythm (SR) with respect to quality of life, distance in 6-minute walking test, and left ventricular reverse remodeling. Despite the beneficial effects of CRT, death from refractory heart failure at 12 months was higher in patients with AF (17 of 126; 13.5%) than those in SR (14/344; 4.1%; p <0,001). Furthermore, permanent AF was an independent predictive factor for mortality from refractory heart failure (hazard ratio 5.4, 95% confidence interval 1.9 to 15.1). In conclusion, patients with AF treated with CRT who survived at the 12-month follow-up had the same functional improvement and remodeling as those in SR. However, AF was an independent risk factor for mortality from heart failure after CRT implantation.

Implantable device therapy

Sudden cardiac death (SCD) accounts for two-thirds of fatal events related to heart disease. Coronary heart disease and non-ischemic cardiomyopathy are the most common causes of SCD. Data from major randomized trials have consistently shown that therapy with an implantable cardioverter defibrillator (ICD) results in a significant and meaningful effect on survival through a reduction in the risk of SCD in these population. These data have resulted in a marked increase in the application of implantable device therapy in the past 2 decades from secondary prevention with an implantable cardioverter/defibrillator (ICD) in survivors of a cardiac arrest to primary prevention of SCD in asymptomatic patients with ischemic and non-ischemic left ventricular dysfunction, and prevention of symptomatic heart failure progression and death with cardiac resynchronization therapy (CRT), and devices that combine CRT and ICD therapies (CRT-D). However, there are still areas of uncertainty regarding device therapy that include inconsistent benefit in risk-subgroups of patients with low ejection fraction; increased risk of heart failure after life-prolonging ICD therapy, and a considerable rate of device malfunction despite increasing sophistication. In the present review we focus on current data regarding the clinical indications as well as the safety and efficacy of implantable device therapy, including ICD, CRT, and CRT-D.

Management of atrial fibrillation in patients with heart failure

BACKGROUND

There is a well-documented relationship and a complex interaction between atrial fibrillation (AF) and heart failure. The coexistence of these 2 clinical entities renders their management even more challenging.

METHODS AND RESULTS

We searched current literature to review the management of AF in patients with heart failure. The cornerstones of AF treatment are rate control, cardioversion, and maintenance of sinus rhythm (SR), and prevention of thromboembolism. The issue of rhythm versus rate control remains unresolved. Nonpharmacologic therapies such as radiofrequency catheter ablation of the atrioventricular node with permanent pacemaker implantation, curative catheter ablation of AF, and cardiac resynchronization therapy are emerging and may alter the management of these patients.

CONCLUSION

Treatment of atrial fibrillation in the setting of heart failure encompasses a variety of approaches including drugs, devices, and ablation. Larger randomized trials are required to clarify the management of such patients.

A randomized comparison of triple-site versus dual-site ventricular stimulation in patients with congestive heart failure

OBJECTIVES

We compared the effects of triple-site versus dual-site biventricular stimulation in candidates for cardiac resynchronization therapy.

BACKGROUND

Conventional biventricular stimulation with a single right ventricular (RV) and a single left ventricular (LV) lead is associated with persistence of cardiac dyssynchrony in up to 30% of patients.

METHODS

This multicenter, single-blind, crossover study enrolled 40 patients (mean age 70 +/- 9 years) with moderate-to-severe heart failure despite optimal drug treatment, a mean LV ejection fraction of 26 +/- 11%, and permanent atrial fibrillation requiring cardiac pacing for slow ventricular rate. A cardiac resynchronization therapy device connected to 1 RV and 2 LV leads, inserted in 2 separate coronary sinus tributaries, was successfully implanted in 34 patients. After 3 months of biventricular stimulation, the patients were randomly assigned to stimulation for 3 months with either 1 RV and 2 LV leads (3-V) or to conventional stimulation with 1 RV and 1 LV lead (2-V), then crossed over for 3 months to the alternate configuration. The primary study end point was quality of ventricular resynchronization (Z ratio). Secondary end points included reverse LV remodeling, quality of life, distance covered during 6-min hall walk, and procedure-related morbidity and mortality. Data from the 6- and 9-month visits were combined to compare end points associated with 2-V versus 3-V.

RESULTS

Data eligible for protocol-defined analyses were available in 26 patients. No significant difference in Z ratio, quality of life, and 6-min hall walk was observed between 2-V and 3-V. However, a significantly higher LV ejection fraction (27 +/- 11% vs. 35 +/- 11%; p = 0.001) and smaller LV end-systolic volume (157 +/- 69 cm(3) vs. 134 +/- 75 cm(3); p = 0.02) and diameter (57 +/- 12 mm vs. 54 +/- 10 mm; p = 0.02) were observed with 3-V than with 2-V. There was a single minor procedure-related complication.

CONCLUSIONS

Cardiac resynchronization therapy with 1 RV and 2 LV leads was safe and associated with significantly more LV reverse remodeling than conventional biventricular stimulation.

Long-term survival in patients undergoing cardiac resynchronization therapy: the importance of performing atrio-ventricular junction ablation in patients with permanent atrial fibrillation

AIMS

To investigate the effects of cardiac resynchronization therapy (CRT) on survival in heart failure (HF) patients with permanent atrial fibrillation (AF) and the role of atrio-ventricular junction (AVJ) ablation in these patients.

METHODS AND RESULTS

Data from 1285 consecutive patients implanted with CRT devices are presented: 1042 patients were in sinus rhythm (SR) and 243 (19%) in AF. Rate control in AF was achieved by either ablating the AVJ in 118 patients (AVJ-abl) or prescribing negative chronotropic drugs (AF-Drugs). Compared with SR, patients with AF were significantly older, more likely to be non-ischaemic, with higher ejection fraction, shorter QRS duration, and less often received ICD back-up. During a median follow-up of 34 months, 170/1042 patients in SR and 39/243 in AF died (mortality: 8.4 and 8.9 per 100 person-year, respectively). Adjusted hazard ratios were similar for all-cause and cardiac mortality [0.9 (0.57-1.42), P = 0.64 and 1.00 (0.60-1.66) P = 0.99, respectively]. Among AF patients, only 11/118 AVJ-abl patients died vs. 28/125 AF-Drugs patients (mortality: 4.3 and 15.2 per 100 person-year, respectively, P < 0.001). Adjusted hazard ratios of AVJ-abl vs. AF-Drugs was 0.26 [95% confidence interval (CI) 0.09-0.73, P = 0.010] for all-cause mortality, 0.31 (95% CI 0.10-0.99, P = 0.048) for cardiac mortality, and 0.15 (95% CI 0.03-0.70, P = 0.016) for HF mortality.

CONCLUSION

Patients with HF and AF treated with CRT have similar mortality compared with patients in SR. In AF, AVJ ablation in addition to CRT significantly improves overall survival compared with CRT alone, primarily by reducing HF death.

Persistent atrial fibrillation worsens heart rate variability, activity and heart rate, as shown by a continuous monitoring by implantable biventricular pacemakers in heart failure patients

BACKGROUND

Atrial fibrillation (AF) induces loss of atrial contribution, heart rate irregularity, and fast ventricular rate.

OBJECTIVES

The objectives of the study were to accurately measure AF incidence and to investigate the mutual temporal patterns of AF and heart failure (HF) in patients indicated to cardiac resynchronization therapy.

METHODS

Four hundred ten consecutive patients (70% male, age 69 +/- 11) with advanced HF (NYHA = 3.0 +/- 0.6), low ejection fraction (EF = 27 +/- 9%), and ventricular conduction delay (QRS = 165 +/- 29 ms) received a biventricular pacemaker. Enrolled patients were divided into two groups: G1 = 249 patients with no AF history, G2 = 161 patients with history of paroxysmal/persistent AF.

RESULTS

In a median follow-up of 13 months, AF episodes longer than 5 minutes occurred in 105 of 249 (42.2%) G1 patients and 76 of 161 (47.2%) G2 patients, while AF episodes longer than one day occurred in 14 of 249 (5.6%) G1 patients and in 36 of 161 (22.4%) G2 patients. Device diagnostics monitored daily values of patient activity, night heart rate (NHR), and heart rate variability (HRV). Comparing 30-day periods before AF onset and during persistent AF, significant (P < 0.0001) changes were observed in patient activity, which decreased from 221 +/- 13 to 162 +/- 12 minutes, and in NHR, which increased from 68 +/- 3 to 94 +/- 7 bpm. HRV significantly decreased (from 75 +/- 5 ms before AF onset to 60 +/- 6 ms after AF termination). NHR during AF was significantly (P < 0.01) and inversely correlated (R(2)= 0.73) with activity, with a significant lower activity associated with NHR >or= 88 bpm.

CONCLUSION

AF is frequent in HF patients. Persistent AF is associated with statistically significant decrease in patient activity and HRV and NHR increase.

Remission of left ventricular systolic dysfunction and of heart failure symptoms after cardiac resynchronization therapy: temporal pattern and clinical predictors

BACKGROUND

The aim of the study was to determine whether cardiac resynchronization therapy (CRT) may induce a heart failure (HF) remission phase (recovery to New York Heart Association functional class I-II and regression of left ventricular [LV] dysfunction: LV ejection fraction [EF] > or = 50%) and to define the incidence and predictors of such a process.

METHODS

Cardiac resynchronization therapy devices were successfully implanted in 520 consecutive HF patients from 1999 to 2006 (mean age 66 years, 82% male sex, New York Heart Association class > or = II, LVEF 28%, QRS 164 milliseconds, 6-minute hall walk distance 302 m) at our institution. Follow-up data were prospectively collected every 3 to 6 months. Continuous variables were stratified in tertiles.

RESULTS

Over a median follow-up of 28 months, 26% of patients achieved LV remission (rate: 16 per 100 person-years). At univariate analysis, female sex (P = .032), non-coronary artery disease (CAD) etiology (P < .001), mitral regurgitation < 2/4 (P = .022), higher EF tertile (P < .001), lower diameter and volume tertiles (both P < .001), previous conventional right ventricle pacing (P = .029), and post-CRT-paced QRS (P = .008) predicted remission. At multivariate analysis, non-CAD etiology, LVEF 30% to 35%, and LV end-diastolic volume < 180 mL were strongly associated with HF remission phase (all P < .001). Concomitance of these 3 factors yielded a significantly higher remission rate compared with either no or only 1 factor (respectively, 60 vs 7 and 11 per 100 person-years, P < .001).

CONCLUSIONS

Cardiac resynchronization therapy induces HF remission phase in 26% of patients, even after 3 years. Non-CAD etiology and moderately compromised LV function at baseline may easily predict this process.

Fusion beat in patients with heart failure treated with left ventricular pacing: may ECG morphology relate to mechanical synchrony? A pilot study

BACKGROUND

Electrical fusion between left ventricular pacing and spontaneous right ventricular activation is considered the key to resynchronisation in sinus rhythm patients treated with single-site left ventricular pacing.

AIM

Use of QRS morphology to optimize device programming in patients with heart failure (HF), sinus rhythm (SR), left bundle branch block (LBBB), treated with single-site left ventricular pacing.

METHODS AND RESULTS

We defined the "fusion band" (FB) as the range of AV intervals within which surface ECG showed an intermediate morphology between the native LBBB and the fully paced right bundle branch block patterns.Twenty-four patients were enrolled. Echo-derived parameters were collected in the FB and compared with the basal LBBB condition. Velocity time integral and ejection time did not improve significantly. Diastolic filling time, ejection fraction and myocardial performance index showed a statistically significant improvement in the FB. Interventricular delay and mitral regurgitation progressively and significantly decreased as AV delay shortened in the FB. The tissue Doppler asynchrony index (Ts-SD-12-ejection) showed a non significant decreasing trend in the FB. The indications provided by the tested parameters were mostly concordant in that part of the FB corresponding to the shortest AV intervals.

CONCLUSION

Using ECG criteria based on the FB may constitute an attractive option for a safe, simple and rapid optimization of resynchronization therapy in patients with HF, SR and LBBB.

[Electrotherapy of cardiac failure]

Intracardiac conduction disturbances, mostly manifested as a left bundle branch block (LBBB), are common findings in cardiac failure and associated with a poor prognosis. LBBB is a marker of disease progression and also leads to worsened cardiac hemodynamics by dyssynchronous contraction that can accelerate progression of the underlying disease. Cardiac resynchronization therapy (CRT) can reduce the negative effects of these disturbances leading to improvement in hemodynamics and long-term improvement in cardiopulmonary exercise tolerance, reduction of left ventricular volumes and functional mitral regurgitation. Prospective multicenter studies, such as the CARE-HF and COMPANION trials have demonstrated reduced mortality with CRT or combined treatment with defibrillator capability (CRT-D). Thus, CRT has been adopted in the current guidelines of cardiology societies. Nevertheless, there are a number of open issues with CRT, such as the high number of non-responders or the value of CRT in patients with atrial fibrillation, narrow QRS complex and mild cardiac failure or asymptomatic left ventricular dysfunction. In addition, the question whether every CRT patient needs a device with defibrillating capabilities is not fully resolved, at least for patients with dilative cardiomyopathy.

Management of atrial fibrillation

Atrial fibrillation is the most common sustained cardiac rhythm disorder, and confers a substantial mortality and morbidity from stroke, thromboembolism, heart failure, and impaired quality of life. With the increasingly elderly population in the developed world, as well as improvements in the management of myocardial infarction and heart failure, the prevalence of atrial fibrillation is increasing, resulting in a major public-health problem. This Review aims to provide an overview on the modern management of atrial fibrillation, with particular emphasis on pharmacological and non-pharmacological approaches. Irrespective of a rate-control or rhythm-control strategy, stroke prevention with appropriate thromboprophylaxis still remains central to the management of this common arrhythmia. Electrophysiological approaches could hold some promise for a curative approach in atrial fibrillation.

Comparison of usefulness of cardiac resynchronization therapy in patients with atrial fibrillation and heart failure versus patients with sinus rhythm and heart failure

The prevalence of atrial fibrillation (AF) in patients with heart failure is high, but data about the effects of cardiac resynchronization therapy (CRT) in patients with chronic AF are scarce. In this prospective observational study of 263 consecutive patients, CRT was performed in 96 patients (37%) with chronic AF and 167 patients (63%) with sinus rhythm (SR). Echocardiographic and clinical parameters were evaluated at baseline and 3 and 12 months. Reverse left ventricular (LV) remodeling is defined as LV end-systolic volume decrease > or =10%. Hospitalization rates for heart failure in the year before and after implantation were compared. Baseline characteristics between patients with and without AF were similar, but the AF group had smaller LV end-systolic and end-diastolic volumes and larger left atrial dimensions. New York Heart Association class, 6-minute walking distance, quality-of-life score, LV ejection fraction, and mitral regurgitation improved significantly at 3 and 12 months in both groups, and the changes were similar. Reverse LV remodeling after 3 and 12 months was 74% and 82% (AF group) versus 77% and 83%, respectively (SR group, p = 0.79). After 1 year, cardioversion had occurred in 25% of patients with AF. In the year after implantation, significant decreases in hospitalizations for heart failure in both groups (84% and 90%) were documented. Long-term mortality was almost equal in both groups. In conclusion, this large-scale study shows that the benefit of CRT in patients with chronic AF and heart failure is similar to that in patients with SR. Patients with chronic AF and heart failure should be considered candidates for CRT.

Resynchronization therapy in the context of atrial fibrillation: Benefits and limitations

Atrial fibrillation (AF) and heart failure often coexist and are believed to directly predispose to each other. Cardiac resynchronization does not prevent or increase the induction of AF. However, new onset of AF does not seem to diminish the beneficial effects of CRT on symptoms, cardiac function and, more importantly, all-cause mortality if appropriate ventricular rate control by beta-blockers and digoxin is being achieved. While a pharmacological approach to control ventricular rate may be sufficient in most patients with paroxysmal AF or AF of shorter duration in those with permanent AF ablation strategies may be necessary. Observational studies and one randomized trial indicate a potential benefit of CRT in heart failure patients with chronic AF; particularly, biventricular pacing was superior compared to conventional right-univentricular stimulation. However, recent results suggest that even relatively high percentage biventricular capture may be inadequate, and that the benefits of CRT may only be extended to chronic AF patients with previous AV junctional ablation. Well designed and powered clinical trials are required before pacemaker dependency is created in large numbers of heart failure patients.

Therapeutic and diagnostic role of electrical devices in acute heart failure

Electrical devices, Cardiac Resynchronization Therapy (CRT) pacemakers, the Implantable Cardiac Defibrillator (ICD) and a combination of both, constitute an important line of treatment in the therapy of moderate to severe chronic heart failure. The effectiveness of these devices in the treatment of acute decompensated heart failure has yet to be systematically evaluated. However, the beneficial clinical effects of CRT translate into a marked reduction of heart failure-related hospitalization. Devices also offer unique diagnostic applications by continuous measurement of clinically useful physiological parameters over time. Of particular interest, monitoring of intrathoracic impedance and right ventricular pressures allows to detect changes in volume load in an early stage prior to the development of clinical symptoms. This information could be helpful to stop further progression to acute cardiac decompensation and to avoid hospitalization and acute clinical events. Using modern telecommunication technology, patients can also be remotely monitored in their daily living environment. In consequence, the incorporation of device technology into heart failure management programs calls for a close cooperation between heart failure specialists and electrophysiologists. This review addresses therapeutic and diagnostic aspects of device therapies in the context of acute heart failure.

Long-term survival of patients with heart failure and ventricular conduction delay treated with cardiac resynchronization therapy

This multicenter longitudinal observational trial was designed to analyze the long-term outcome of patients with heart failure (HF) treated with cardiac resynchronization therapy (CRT) alone or with implantable cardioverter-defibrillator (ICD) backup in a daily practice scenario. It is unknown whether the magnitude of survival benefits conferred by CRT in a daily practice scenario is comparable to what has been observed in randomized controlled trials and whether this benefit is sustained over the long term. The outcome of 1,303 consecutive patients with ischemic or nonischemic cardiomyopathy on optimal pharmacologic therapy treated from August 1, 1995 to August 1, 2004 at 4 European centers with CRT alone (44%) or with ICD backup for symptomatic HF and prolonged QRS duration was assessed. Cumulative event-free survival was evaluated for a combined end point, defined as death from any cause, urgent transplantation, or implantation of a left ventricular assist device. The cumulative incidence of competing events, HF, sudden cardiac death, and noncardiac death, was also assessed. Event-free survival was similar across the different centers. At 1 and 5 years, cumulative event-free survivals were 92% (95% confidence interval [CI] 91 to 94) and 56% (95% CI 48 to 64), respectively. The cumulative incidence of HF deaths was 25.1% (95% CI 19 to 31.7), whereas that of sudden death was 9.5% (95% CI 5.1 to 15.7). Using multivariate analysis, CRT with an ICD backup was associated with a nonsignificant decrease in mortality by 20% (hazard ratio 0.83, 95% CI 0.58 to 1.17, p = 0.284), with a highly significant protective effect against sudden cardiac death (hazard ratio 0.04, 95% CI 0.04 to 0.28, p <0.002). In conclusion, patients with advanced HF and a wide QRS complex routinely treated with CRT have a favorable long-term outcome that was reproducible at different centers. The leading cause of death in these patients remained HF, and this mode of death was competing with other causes in determining outcome. Total mortality was 20% lower with ICD backup (95% CI 42% lower to 17% higher) due to a protective effect against sudden cardiac death.

Three Years of Cardiac Resynchronization Therapy: Could Superior Benefits be Obtained in Patients with Heart Failure and Narrow QRS?

AIM OF THE STUDY

To examine the long-term effects of cardiac resynchronization therapy (CRT) in patients presenting with heart failure (HF) and QRS </= 120 ms.

METHODS

This was a prospective, longitudinal study of 376 patients [mean age = 65 years, mean left ventricular (LV) ejection fraction (EF) = 29%, mean QRS duration = 165 ms, mean distance covered during a 6-minute hall walk (6-MHW) = 325 m], who underwent successful implantation of CRT systems. The QRS duration at baseline was </= 120 ms in 45 patients (12%) who were not pre-selected by echocardiographic criteria of dyssynchrony, and > 120 ms in the remaining 331 patients. The baseline characteristics of the 2 groups were similar. We evaluated indices of cardiac function, percentage of responders, and survival rates over a mean 28-month follow-up.

RESULTS

Both groups experienced similar long-term increases in 6-MHW, and decreases in New York Heart Association functional class and LV end-systolic volume (all comparisons P < 0.0001 in both groups). Time interaction of changes in LVEF and percentage of responders were significantly different (P = 0.03 and P = 0.004, respectively), in favor of the narrow QRS group, where the changes were sustained and persisted at 2 and 3 years. The long-term death rate from HF was lower in the group with narrow than in the group with wide QRS complex (P = 0.04; log-rank test).

CONCLUSIONS

CRT confers considerable long-term clinical, functional, and survival benefits in patients presenting with HF and narrow QRS, not preselected by echocardiographic criteria of dyssynchrony. Caution is advised before denying CRT to these patients on the basis of QRS width only.