Frequency of inter- and intraventricular dyssynchrony in patients with heart failure according to QRS width

Abstract Aims Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure patients with prolongation of QRS duration. Despite careful patient selection, some do not respond to CRT based on QRS complex duration. We sought to evaluate the presence of left ventricular dyssynchrony using tissue Doppler imaging (TDI) according to QRS duration in heart failure patients. Methods and results Ninety-nine patients (mean age 52.6 ± 15.3 years) with severe heart failure [left ventricular (LV) ejection fraction, 33.4 ms and Ts-diff >100 ms) were correlated with the QRS width and morphology. We found a greater IVMD in Group II patients, compared with patients in Group I (42.5 ± 22.3 vs. 26.8 ± 21, respectively, P < 0.001). Intraventricular dyssynchrony defined as Ts-SD ≥33.4 ms was found in 45.1% of patients in Group II compared with 23% of patients in Group I (P = 0.03). Similarly, the Ts-diff was prolonged in Group II patients compared with Group I (P = 0.02). By linear regression analysis, a weak relation was found between Ts-SD and QRS duration (P = 0.055). A substantial portion of patients with prolonged QRS did not exhibit ventricular dyssynchrony defined either as total asynchrony index ≥33.4 ms or as IVMD >40 ms. Conclusion A substantial proportion of patients with prolonged QRS (32.1%) did not exhibit inter- or intraventricular dyssynchrony, which may represent a limitation in identifying the ideal QRS interval for the selection of patients for CRT.