Aims: In post-operative setting after cardiac surgery, the choice of the optimal ventricular pacing site remains an issue, particularly in patients with ischaemic cardiomyopathy. We aimed to investigate the impact of the left ventricular (LV) pacing site in an animal model of incremental myocardial ischaemia.
Methods and results: Three epicardial LV pacing leads were implanted in 10 pigs [LV1 in the territory of the left anterior descending (LAD) artery, LV2 in the lateral border of this territory, LV3 in an anatomically opposed position]. A two-dimensional strain echocardiogram was performed at baseline and during two levels of incremental ischaemia, corresponding to 30 and 70% reduction of coronary flow in the LAD, during spontaneous sinus rhythm (SR) and during LV1, LV2, LV3, and multi-LV (LV1 + LV2 + LV3) pacing. At baseline (n = 10), LV + dP/dt(max) was decreased (P < 0.01) during LV1, LV2, LV3, and multi-LV pacing compared with SR. At first level of ischaemia (n = 7; 3 animals died from ventricular fibrillation), LV1 pacing (ischaemic area) induced a significant decrease in LV + dP/dt(max) compared with SR, LV2, LV3, and multi-LV pacing (P < 0.05). At second level of ischaemia (n = 6), LV1 pacing induced a significant decrease in LV + dP/dt(max) associated with an increase in the extent of myocardium with echocardiographic post-systolic shortening compared with SR, LV2, LV3, or multi-LV pacing (P < 0.05). In contrast, multi-LV pacing induced a significant haemodynamic improvement compared with SR, LV1, LV2, and LV3 (P < 0.05).
Conclusions: Pacing within an ischaemic area has detrimental impact on acute global and regional LV function. More studies are needed to assess the impact of multi-LV pacing in chronic ischaemic conditions.