“The mechanism of the reduction of myocardial edema by post-conditioning is unclear” note the authors of the report in the June 12 issue of the Journal of the American College of Cardiology. “Our data strongly suggest that it is most likely related to the infarct size-reducing effect because we found a good correlation between infarct size and myocardial edema.”
Dr. Franck Thuny, at the Universite de Lyon and Hopital Cardio-Vasculaire et Pneumologique Louis Pradel, Bron, and colleagues explain that myocardial edema is both a consequence and a cause of reperfusion injury during primary PCI, “with potentially severe consequences.” Post-conditioning during PCI, i.e., brief repeated periods of ischemia, has been shown to reduce infarct size in MI patients, but its effect on myocardial edema has not been documented in the clinical setting.
To investigate, the team randomized 50 patients with ST-segment elevation MI to revascularization by direct stenting with or without post-conditioning. Specifically, in the intervention group, within 1 minute of reflow the angioplasty balloon was re-inflated for 1 minute four times, each separated by 1 minute of reflow.
Myocardial edema was measured by cardiac MRI within 72 hours of admission. Post-conditioning was associated with a 32% reduction in the extent of myocardial edema, which averaged 23 versus 34 g per square meter body surface area (p=0.03) in the intervention and controls groups, respectively.
As expected, the investigators also saw a significant difference in infarct size in the two groups, at 13 vs 21 g/square meter (p=0.01), respectively.
“This randomized controlled trial demonstrated that angioplasty post-conditioning decreased myocardial edema in patients with STEMI,” Dr. Thuny and colleagues conclude. “Additional studies will be required to determine whether myocardial edema may be considered to be a new marker of myocardial reperfusion injury.”