Left Ventricular Lead Location and the Risk of Ventricular Arrhythmias in the MADIT-CRT Trial
Does the left ventricular (LV) lead position affect the risk of ventricular tachycardia/ventricular fibrillation (VT/VF) during cardiac resynchronization therapy (CRT)?
This was a retrospective analysis of 797 patients who received an implantable cardioverter-defibrillator (ICD) with CRT for primary prevention of sudden death. All patients had New York Heart Association class I-II heart failure, an ejection fraction <30%, and QRS >130 ms. The LV lead position was evaluated by coronary venograms and chest X-rays. The primary endpoint was the first occurrence of VT/VF or death during a mean follow-up of 30.6 months.
The LV lead was positioned apically in 14% of patients, anteriorly in 18%, laterally in 56%, and posteriorly in 12%. The risk of VT/VF was 43% lower with a lateral or posterior LV lead than with an anterior lead. The risk of VT/VF was similar in patients with an anterior LV lead position and in patients with an ICD who did not receive CRT. Mortality did not differ significantly between patients with a posterior, lateral, or anterior LV lead.
Compared to an anterior lead position, a posterior or lateral LV lead position decreases the risk of VT/VF in patients undergoing CRT.
Some prior studies reported that CRT increases the risk of VT/VF in patients undergoing CRT, possibly because of heterogeneity of repolarization associated with epicardial pacing. However, other studies have indicated that CRT has an antiarrhythmic effect, possibly related to reverse remodeling. A reassuring finding of the present study is that there was no evidence of proarrhythmia from CRT.
Keywords: Tachycardia, Ventricular, Ventricular Fibrillation, Cardiac Resynchronization Therapy
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