RESUMO
BACKGROUND: Pacemaker-induced cardiomyopathy is a well described phenomenon in patients with preserved ejection fraction at the time of permanent pacemaker implant. One of the identified risk factors for pacemaker-induced cardiomyopathy is the degree of ventricular pacing burden. However, it is unclear how a high right ventricular pacing burden affects patients with depressed left ventricular function at the time of pacemaker implantation. We sought to assess the relationship between right ventricular pacing and change in left ventricular function over time. METHODS: We conducted an analysis of all patients who had received either a single or dual lead cardiac implantable electronic devices, excluding biventricular devices, and had a prior transthoracic echocardiogram demonstrating an ejection fraction of less than 50%. The primary end-point was the correlation between the percentage of ventricular pacing and the change in LV ejection fraction. RESULTS: Fifty eight patients with preceding heart failure had pacemakers implanted and had follow up echocardiograms. There was no correlation between the degree of ventricular pacing and the absolute change in LV function (r = .04, p = .979). None of the previously identified risk factors for pacemaker induced cardiomyopathy were predictive of a significant fall in ejection fraction. CONCLUSION: The degree of RV pacing and other established risk factors for pacemaker-induced cardiomyopathy in patients with normal left ventricular function at the time of implantation do not appear to carry the same risk in patients with pre-existing heart failure who receive either single or dual lead pacemakers.