Background: we have found that remote ischemic conditioning (rIC), adjunctive to primary angioplasty, increases myocardial salvage in patients with ST-segment elevation myocardial infarction (STEMI) and extensive myocardial area at risk (AAR). The present substudy aimed to evaluate the short-term effects of rIC on left ventricular (LV) function.
Methods and results: patients with a first STEMI were randomized to rIC (4 cycles of 5 minutes upper-limb ischemia) during transfer to primary percutaneous coronary intervention (pPCI) (n=123) versus pPCI alone (n=119). Ejection fraction (EF), LV volumes, (2D and 3D echocardiography and myocardial perfusion imaging), and speckle-tracking global longitudinal strain were compared between treatment groups. There was no significant difference in LV function at day 1 (EF-2D, 0.51±0.10 versus 0.49±0.10; P=0.22) and after 30 days (EF-2D, 0.54±0.08 versus 0.53±0.10) between the rIC and the pPCI-alone groups. In patients with extensive AAR ≥35% of LV (n=53), EF after 30 days was higher after rIC than after pPCI alone (EF-2D, 0.51±0.07 versus 0.46±0.09; P=0.05). In patients with anterior infarction (n=97), rIC preserved LV function on day 1 (EF-2D, 0.51±0.11 versus 0.46±0.11; P=0.03) and persistently after 30 days (EF-2D, 0.55±0.08 versus 0.50±0.11; P=0.04; EF-myocardial perfusion imaging, 0.55±0.10 versus 0.49±0.12; P=0.02). These patients had similar AAR, whereas rIC reduced infarct size from 16% to 7% of LV (P=0.01).
Conclusions: although no significant overall effect was observed, rIC seemed to result in modest improvement in LV function in high-risk patients prone to develop large myocardial infarcts. These results need to be confirmed in larger trials.