QRS and QT Interval Changes and Ventricular Arrhythmias Following Continuous Flow Mechanical Unloading of the Failing Human Heart

Purpose The effect of continuous flow left ventricular assist devices (CF-LVAD) on the arrhythmogenicity of the failing heart is a controversial issue. We sought to investigate the association of CF-LVAD unloading on the electrical properties of the failing heart including the incidence of sustained ventricular tachycardia (VT)/ ventricular fibrillation (VF). Methods and Materials The records of 80 CF-LVAD patients from the UTAH Cardiac Transplant Program implanted between 2008 and 2011 were retrospectively reviewed. 12-lead ECGs and ICD interrogations were reviewed. We examined 12 lead ECGs for QRS and QT intervals before, 4 and 12 weeks after CF-LVAD implant. ICD recording episodes of VT and VF were checked before and after LVAD implantation. Results The average age was 55±15 years (75% males) and 53% had non-ischemic cardiomyopathy. The QRS duration was found to be decreased at 4 weeks following CF-LVAD implant and this decrease was sustained at 12 weeks (Table). The QT interval also decreased at 4 and 12 weeks (Table). QRS and QT changes were observed in patients with both paced (n=43; 68.3%) and normal ventricular activation. Twenty eight patients had a history of sustained VT/VF pre CF-LVAD. Twenty one patients had VT/VF episodes following CF-LVAD implant; 8 patients presented with de novo arrhythmias. The majority of ventricular arrhythmias were monomorphic VTs (66.7%); 4 (50%) occurred in the first 4 weeks, while 4 (50%) occurred 4-12 weeks following CF-LVAD. Conclusions Chronic CF-LVAD unloading is associated with shortening of QRS and QT intervals. Ventricular arrhythmias occurred de novo following surgery despite those changes. Further studies are needed to understand the effect of unloading on the ventricular arrhythmogenic milieu and substrate. 4 Weeks post 12 weeks post Pre-LVAD LVAD LVAD P value QT 155±37 ms 128±34 ms 120±41 ms * QRS 446±62 ms 409±77 ms 404±78 ms * * Pre-LVAD to 4 weeks post LVAD