In heart failure patients receiving cardiac resynchronization therapy, those with a narrow QRS complex and LV dyssynchrony had similar NYHA class reduction (0.9 vs 1.1) as those with a wide QRS.
Cohort (n=66)
Absolute Event Rate: 0.9% vs 1.1%
p-value: p=NS
OBJECTIVES: The purpose of this study was to evaluate the effects of cardiac resynchronization therapy (CRT) in heart failure patients with narrow QRS complex ( or =120 ms). Patients with narrow QRS complex are currently not eligible for CRT, and the potential effects of CRT are not well studied. METHODS: Thirty-three consecutive patients with narrow QRS complex and 33 consecutive patients with wide QRS complex (control group) were prospectively included. All patients needed to have LV dyssynchrony > or =65 ms on TDI, New York Heart Association (NYHA) functional class III/IV heart failure, and LV ejection fraction < or =35%. RESULTS: Baseline characteristics, particularly LV dyssynchrony, were comparable between patients with narrow and wide QRS complex (110 +/- 8 ms vs. 175 +/- 22 ms; p = NS). No significant relationship was observed between baseline QRS duration and LV dyssynchrony (r = 0.21; p = NS). The improvement in clinical symptoms and LV reverse remodeling was comparable between patients with narrow and wide QRS complex (mean NYHA functional class reduction 0.9 +/- 0.6 vs. 1.1 +/- 0.6 p = NS and mean LV end-systolic volume reduction 39 +/- 34 ml vs. 44 +/- 46 ml p = NS). CONCLUSIONS: Cardiac resynchronization therapy appears to be beneficial in patients with narrow QRS complex and severe LV dyssynchrony on TDI, with similar improvement in symptoms and comparable LV reverse remodeling to patients with wide QRS complex. The current results need confirmation in larger patient cohorts.
“This should put to rest the question of whether resynchronization has a role in patients with narrow QRS complexes. Clearly biventricular pacing cannot improve upon the native conduction system, and may actually cause harm through worsening interventricular dyssynchrony.”
Bleeker et al. (2006) conducted a cohort in Heart failure with left ventricular dyssynchrony (n=66). Narrow QRS complex (<120 ms) vs. Wide QRS complex (≥120 ms) was evaluated on Mean NYHA functional class reduction (p=NS). In heart failure patients receiving cardiac resynchronization therapy, those with a narrow QRS complex and LV dyssynchrony had similar NYHA class reduction (0.9 vs 1.1) as those with a wide QRS.