Myocardial perfusion recovery induced by an α-calcitonin gene-related peptide analogue

Background Endogenous calcitonin gene-related peptide (CGRP) induces cardioprotective effects through coronary vasodilation. However, the systemic administration of CGRP induces peripheral vasodilation and positive chronotropic and inotropic effects. This study aims to examine the net effect on coronary perfusion of the systemically administered α-calcitonin gene-related peptide analogue, SAX, in rats during myocardial infarction. Methods Forty Sprague-Dawley rats underwent myocardial infarction. Following left anterior descending artery occlusion, [ 99m Tc]Tc-sestamibi was administered to determine the myocardial perfusion before treatment. Twenty minutes, 24 and 48 h after [ 99m Tc]Tc-sestamibi injection, the rats were treated with either SAX or placebo. Final infarct size was determined three weeks later by [ 99m Tc]Tc-sestamibi SPECT/CT scan. Results Thirty-one rats survived the surgery and 20 completed the follow-up SPECT/CT scan (SAX n = 12; Placebo n = 8). At baseline, there was no difference in size of perfusion defect between the groups ( P = .88), but at follow-up the SAX group had improved myocardial recovery compared to the placebo group ( P = .04), corresponding to a relative perfusion recovery of 55% in SAX-treated rats. Conclusion The CGRP analogue, SAX, has a cardioprotective effect in this rat model of myocardial infarction, improving myocardial perfusion recovery after chronic occlusion of the coronary artery.