Heart failure: what proportion of patients satisfy the electrocardiographic criteria for cardiac resynchronization therapy?

BACKGROUND: Cardiac resynchronization therapy has emerged as a new therapeutic modality for patients with congestive cardiac failure and associated intraventricular conduction delay. The purpose of this study was to find out what proportion of Indian patients with congestive heart failure may be candidates for cardiac resynchronization therapy based on electrocardiographic characteristics. METHODS AND RESULTS: One hundred twenty-one consecutive patients with congestive cardiac failure due to various etiologies whose left ventricular ejection fraction was less than 40% were included in the study. Standard 12-lead electrocardiogram was recorded in all the patients, and various parameters (rhythm, conduction, QRS axis, chamber enlargement, chamber hypertrophy, and the presence of Q waves) were analyzed. The study population comprised 82 male (67.8%) and 39 female (32.2%) patients with a mean age of 53 +/- 13 years. Thirty-nine patients (32.2%) had NYHA class I-II symptoms, and 82 (67.8%) had NYHA class III-IV symptoms. The mean QRS duration was 111 +/- 27 ms. Bundle branch block was seen in 43 patients (35.5%), of whom 30 (24.8%) had left bundle branch block, and 13 (10.7%) had right bundle branch block. Of the 30 patients who had left bundle branch block, 19 (15.7%) had a QRS duration of between 120 and 149 ms, and 11 (9%) had a QRS duration > or = 150 ms. In the latter group, 7 patients (5.8%) were in NYHA classes III and IV. As the clinical severity of heart failure increased, the mean QRS duration also increased, but this increment was not statistically significant. CONCLUSIONS: Based on our data, it can be estimated that of the patients with heart failure who attend a tertiary care center, 2 5% of patients present with left bundle branch block. If we use the criteria for NYHA class III and IV congestive cardiac failure with QRS duration of > or = 150 ms in patients with left bundle branch block, 6% of patients are likely to need cardiac resynchronization therapy.