Reverse electrophysiologic remodeling after cardiac mechanical unloading for end-stage nonischemic cardiomyopathy

Abstract

Background: Left ventricular assist devices (LVAD)-induced unloading appear to cause reverse cardiac remodeling. However, its effect on arrhythmogenicity is a controversial issue, and prospective data are lacking. We sought to investigate the impact of LVAD-induced unloading on the electrical properties of the failing heart.

Methods: We prospectively studied the effects of LVAD therapy on QRS, QT, and QTc durations and ventricular arrhythmias from electrocardiograms and 24-hour ambulatory electrocardiograms recorded before and during 6 months of mechanical support in 12 LVAD patients and 7 other patients with advanced nonischemic cardiomyopathy untreated with LVAD.

Results: After 1 week of LVAD support, QTc duration had decreased from 479 ± 79 ms to 411 ± 57 ms (p = 0.037), and QRS duration from 150 ± 46 ms to 134 ± 32 ms (p = 0.029). At 6 months, QTc was found to be 372 ± 56 ms (p = 0.046 versus baseline, 15% shortening) and QRS 118 ± 25 ms (p = 0.028 versus baseline, 11% shortening). A strong correlation was found between QTc shortening and increase in left ventricular ejection fraction and decrease in left ventricular filling pressures. After 2 months of LVAD support, premature ventricular contractions had decreased from 3,507 ± 4,252 to 483 ± 417 in 24 hours (p = 0.043), ventricular couplets from 82 ± 99 to 29 ± 25 in 24 hours (p = 0.05), and ventricular runs from 9 ± 8 to 10 ± 9 (not significant). No patient died suddenly or suffered a symptomatic arrhythmic event during follow-up. No significant electrocardiographic, functional, or hemodynamic change was observed in the 7 patients untreated with LVAD.

Conclusions: The LVAD support caused progressive shortening of QTc and QRS intervals, consistent with reverse remodeling of the failing heart's electrical properties, accompanied by a decrease in frequency of ventricular arrhythmias.