Study Suggests Intracoronary Enalaprilat May Reduce Microvascular Damage During PCI

February 5, 2013—In the Journal of the American College of Cardiology, Fabio Mangiacapra, MD, et al published findings from the ProMicro study, which investigated the influence of intracoronary enalaprilat on coronary microvascular function and periprocedural outcome measures in patients with stable angina undergoing percutaneous coronary intervention (PCI) (2013;61:615–621).

As noted in the Journal of the American College of Cardiology, intracoronary angiotensin-converting enzyme inhibitors have been shown to relieve myocardial ischemia in stable patients and to improve epicardial flow in patients with ST-segment elevation myocardial infarction; however, it is still unclear whether these effects are mediated by a modulation of the coronary microcirculation.

The investigators randomly assigned 40 patients to receive either an intracoronary bolus of enalaprilat (50 μg) or placebo before elective PCI. The index of microvascular resistance was measured at baseline, 10 minutes after study drug administration, and after PCI. High-sensitivity cardiac troponin T was measured as a marker of myocardial injury.

The investigators reported that infusion of enalaprilat resulted in a significant reduction in index of microvascular resistance (27 ± 11 at baseline vs 19 ± 9 after drug vs 15 ± 8 after PCI), whereas a significant postprocedural increase in index of microvascular resistance was observed in the placebo group (24 ± 15 at baseline vs 24 ± 15 after drug vs 33 ± 19 after PCI). Index of microvascular resistance levels after PCI were significantly lower in the enalaprilat group (P < .001). Patients pretreated with enalaprilat also showed lower peak values (mean: 21.7 ng/mL, range: 8.2 to 34.8 ng/mL vs mean: 32.3 ng/mL, range: 12.6 to 65.2 ng/mL; P = .048), as well as periprocedural increases of high-sensitivity cardiac troponin T (mean: 9.9 ng/mL, range: 2.7 to 19 ng/ml vs mean: 26.6 ng/mL, range: 6.3 to 60.5 ng/mL; P = .025).

As stated in the Journal of the American College of Cardiology, intracoronary enalaprilat was found to improve coronary microvascular function and protect myocardium from procedure-related injury in patients with coronary artery disease undergoing PCI. Larger studies are warranted to investigate whether these effects of enalaprilat could result in a significant clinical benefit, advised the investigators.