ABSTRACT
BACKGROUND: Previous studies report that the optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricular (LV) lateral and postero-lateral (PL) wall. However, little is known regarding whether pacing over an akinetic site impacts the contractile response and long-term outcome from CRT. METHODS AND RESULTS: A total of 38 patients with ischemic cardiomyopathy were studied for their acute hemodynamic and 12-month clinical response to CRT. The intraindividual percentage change in dP/dt (%DeltadP/dt), over baseline, was derived from the mitral regurgitation (MR) Doppler profile with CRT on versus off. Two-dimensional echocardiography was used for myocardial segmentation and determinination of akinetic sites. LV lead implant site was determined using angiographic and radiographic data and categorized as being "on" (group 1) or "off" (group 2) an akinetic site. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to primary endpoint was estimated by the Kaplan-Meier method. Clinical characteristics and acute hemodynamic response was similar in both (group 1 [n = 14]; %DeltadP/dt 48.8 +/- 67.4% vs group 2 [n = 24]; %DeltadP/dt 32.2 +/- 40.1%, P = 0.92). No difference in long-term outcome was observed (P = 0.59). In contrast, lead placement in PL or mid-lateral (ML) positions was associated with a better acute hemodynamic response when compared to antero-lateral (AL) positions (PL, %DeltadP/dt 45.7 +/- 50.7% and ML, %DeltadP/dt 45.1 +/- 58.8% vs AL, %DeltadP/dt 2.9 +/- 30.9%, respectively, P = 0.014). CONCLUSION: LV lead proximity to an akinetic segment does not impact acute hemodynamic or 12-month clinical response to CRT.
