Effects of cardiac resynchronisation on maximal and submaximal exercise performance in advanced heart failure patients with conduction abnormality

Cardiac Resynchronization Therapy: A Practical Guide for Patient Management After Device Implantation, Part II

This is the second of a two-part series on strategies for optimizing the delivery of cardiac resynchronization therapy (CRT). A previous article presented strategies to optimize CRT device functioning. This article focuses on patient-related aspects. The 2005 American College of Cardiology/American Heart Association (ACC/AHA) Guidelines for Managing Adults with Chronic Heart Failure now designate CRT as a class IA recommendation for stage C patients (QRS duration, > or = 120 milliseconds; left ventricular ejection fraction, < or = 35%) who remain symptomatic despite optimal medical therapy. While the evidence from prospective randomized controlled trials demonstrates consistent and concordant support for CRT in patients with symptomatic heart failure and ventricular dyssynchrony, a substantial minority of patients do not experience clinical improvement from CRT. In addition to device optimization, optimizing individual patient responses is essential. This article discusses measures for enhancing the patient's response to a CRT device.

Cardiac Resynchronization Therapy

Heart failure is a major health problem in the United States, associated with high morbidity, mortality, and economic burden. Despite recent advances in pharmacological treatments to attenuate disease progression, medications become relatively ineffective, resulting in worsening congestive symptoms and increased exercise intolerance. Cardiac resynchronization therapy provides a new adjunct for heart failure patients who remain symptomatic despite optimized medical therapies. This article discusses cardiac resynchronization therapy and measures that should be considered to ensure proper functioning of the device and improved quality of life for patients.

Cardiac resynchronization and death from progressive heart failure: a meta-analysis of randomized controlled trials

CONTEXT

Progressive heart failure is the most common mechanism of death among patients with advanced heart failure. Cardiac resynchronization, a pacemaker-based therapy for heart failure, enhances cardiac performance and quality of life, but its effect on mortality is uncertain.

OBJECTIVE

To determine whether cardiac resynchronization reduces mortality from progressive heart failure.

DATA SOURCES

MEDLINE (1966-2002), EMBASE (1980-2002), the Cochrane Controlled Trials Register (Second Quarter, 2002), The National Institutes of Health ClinicalTrials.gov database, the US Food and Drug Administration Web site, and reports presented at scientific meetings (1994-2002). Search terms included pacemaker, pacing, heart failure, dual-site, multisite, biventricular, resynchronization, and left ventricular preexcitation.

STUDY SELECTION

Eligible studies were randomized controlled trials of cardiac resynchronization for the treatment of chronic symptomatic left ventricular dysfunction. Eligible studies reported death, hospitalization for heart failure, or ventricular arrhythmia as outcomes. Of the 6883 potentially relevant reports initially identified, 11 reports of 4 randomized trials with 1634 total patients were included in the meta-analysis.

DATA EXTRACTION

Trial reports were reviewed independently by 2 investigators in an unblinded standardized manner.

DATA SYNTHESIS

Follow-up in the included trials ranged from 3 to 6 months. Pooled data from the 4 selected studies showed that cardiac resynchronization reduced death from progressive heart failure by 51% relative to controls (odds ratio [OR], 0.49; 95% confidence interval [CI], 0.25-0.93). Progressive heart failure mortality was 1.7% for cardiac resynchronization patients and 3.5% for controls. Cardiac resynchronization also reduced heart failure hospitalization by 29% (OR, 0.71; 95% CI, 0.53-0.96) and showed a trend toward reducing all-cause mortality (OR, 0.77; 95% CI, 0.51-1.18). Cardiac resynchronization was not associated with a statistically significant effect on non-heart failure mortality (OR, 1.15; 95% CI, 0.65-2.02). Among patients with implantable cardioverter defibrillators, cardiac resynchronization had no clear impact on ventricular tachycardia or ventricular fibrillation (OR, 0.92; 95% CI, 0.67-1.27).

CONCLUSIONS

Cardiac resynchronization reduces mortality from progressive heart failure in patients with symptomatic left ventricular dysfunction. This finding suggests that cardiac resynchronization may have a substantial impact on the most common mechanism of death among patients with advanced heart failure. Cardiac resynchronization also reduces heart failure hospitalization and shows a trend toward reducing all-cause mortality.