Spontaneous QRS complex narrowing predicts left ventricle reverse remodeling in CRT patients

Abstract

Mechanical cardiac dyssynchrony is an important component of cardiac remodeling during heart failure with reduced ejection fraction. Furthermore, echocardiographic assessment of left ventricle reverse remodelingrepresents the major tool to evaluate cardiac resynchronization therapy (CRT) response. In contrast, according to major randomized trialsmechanical dyssynchrony assessment failed and electrocardiographic proof of dyssynchrony is needed to indicate CRT, therefore; electrical reverse remodeling was suggested by few clinical studies conducted with a small number of patients. Additional information is required on the relationship between electrical (ERR) and structural reverse remodeling (SRR) in patients treated with cardiac resynchronization therapy. We investigated whether ERR defined as narrowing of the native electrocardiographic QRS duration after CRT might predict improvement in echocardiographic outcome. We collected 75 patients who underwent successful CRT device implantation in our department. Clinical, electrocardiographic and echocardiographic parameters were collected before implantation and after a variable duration of follow up in the outpatient clinic. SRR was defined as an improvement of LVEF > 5% and/or a reduction in LVESV > 15%. ERR was defined as a decrease in native QRS duration > 10 milliseconds (was recorded after switching off biventricular pacing). After a mean follow up duration of 69 months from the time of implantation, 51 patients had an echocardiographic response (SRR) and among 45 patients who had demonstrated an electrocardiographic response (ERR), 75% developed SRR (vs. 55% for those without ERR P = 0.07) and only 7.5% of them were ischemic cardiomyopathy. Mean QRS reduction was at 16 milliseconds in patients with SRR versus 8 milliseconds in patients without SRR (P = 0.02). Reversal electric remodeling as assessed by native QRS narrowing was associated with greater improvements in mean LVEF (16% vs. 10%, P = 0.1), mean LVEDV (85 mL vs. 35 mL, P = 0.04) and mean LVESV (77 mL vs. 37 mL, P = 0.1). Native QRS narrowing after initiation of CRT in patients with HFrEF was positively correlated tostructural reverse remodeling parameters assessed by echocardiography and consequently to the echocardiographic outcome.