Cardiac Resynchronization Therapy in Heart Failure Patients with Narrow QRS

Abstract

Background: Cardiac resynchronization therapy (CRT) is an established therapy for severe symptomatic heart failure with depressed left ventricle (LV) systolic function and a wide QRS >120 ms. However only 30% heart failure patients will fulfill this criteria. Studies have demonstrated benefits of CRT with narrow QRS <120 ms with mechanical dyssynchrony. Aim: The aim of study was to evaluate the benefit of CRT in heart failure patients with narrow QRS <120 ms with mechanical dyssynchrony. Methods: 72 optimally managed heart failure patients in sinus rhythm, narrow QRS <120 ms, NYHA class III & IV, LV systolic EF <35% with mechanical dyssynchrony demonstrated by Tissue Doppler Imaging (TDI) were implanted with a CRT device. Clinical and echocardiography assessment was performed at baseline, 6 and 12 months. 55 patients completed 12 months follow up. Results: At 12 months 65 patients completed the study. There was significant improvement clinically in NYHA functional class (p<0.001) and 6 min walk (p<0.001). There was significant reduction of LV end systolic diameter (from 56.8±7.4 mm to 53.5±7.8 mm) p<0.001 and LV end diastolic from (66.3±7.6 to 63.8±7.3 mm) p<0.001. LV systolic EF improved significantly from (26.7±5.7% to 32.4±8.0%) p<0.001. Conclusions: CRT in heart failure with narrow QRS and mechanical dyssynchrony result in clinical improvement and LV reverse remodeling. CRT should be offered to heart failure patients with evidence of mechanical dyssynchrony.