Safety and efficacy of external electrical cardioversion in patients with left ventricular leads

Atrial arrhythmias lower the biventricular pacing percentage in cardiac resynchronization therapy (CRT) treated patients (pts) and have a high prevalence in this population. External electrical cardioversion (ECV) is commonly performed to restore sinus rhythm. There is a paucity of data on the safety and efficacy of ECV in pts with CRT devices.

Forty-three pts with CRT devices undergoing ECV at two centers were included prospectively. Devices were interrogated immediately prior to and after ECV, as well as after 4 weeks.

Devices (CRT-D in 38 and CRT-P in 5) were all implanted in left pectoral position, with predominantly bipolar left ventricular (LV) leads. Sixty-one shocks were delivered, all biphasic. Arrhythmia had recurred in 36 % of pts at follow-up (FU). There was a significant increase in LV lead threshold voltage and drop in bipolar LV lead impedance after ECV, which returned to normal at FU. An at least twofold increase in pacing threshold voltage at FU was seen in 2 LV leads and a 0.5 V increase in threshold in 3 LV leads. Overall, biventricular pacing significantly increased during FU.

ECV in CRT pts was safe and effective in this two-center study. A transient increase in LV lead pacing threshold was observed. Relevant changes in pacing threshold at FU occurred in five LV leads-identification and regular FU of these pts are necessary. Restoring SR through ECV significantly increased the biventricular pacing percentage but arrhythmia recurrence was frequent. CRT pts with atrial arrhythmias require close FU after ECV.