Postconditioning During PCI for STEMI Fails to Provide Early Benefit in Randomized Trial

November 18, 2016—Recent research from the Minneapolis Heart Institute Foundation has found that postconditioning­, the application of brief periods of ischemia during the initial phase of reperfusion, failed to show an early benefit for patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) and stenting.

The researchers undertook the study after their earlier findings in a previously published small, nonrandomized study demonstrated that patients who underwent postconditioning had improved left ventricular (LV) function following myocardial infarction. The recent clinical trial attempted to improve upon previous trials from Europe and Asia that found postconditioning had mixed results in the setting of STEMI.

“We sought to study the most optimal patient population with STEMI that could benefit from postconditioning to see if it is really effective,” commented Jay Traverse, MD, Principal Investigator of the study. “To accomplish that, we only enrolled patients with a totally occluded major coronary artery on presentation without evidence of collateral blood flow, with limited ischemic times between 1 and 6 hours, and no evidence of preinfarction angina, a powerful mitigator of infarct size.”

The MRI-based study randomized 165 patients to postconditioning followed by PCI and stenting versus routine primary PCI and stenting. The postconditioning intervention consisted of four, 30-second balloon inflations separated by 30 seconds of reperfusion. A total of 101 patients met final enrollment criteria and underwent MRI measurements of infarct size and myocardial salvage 1 to 3 days after PCI.

“Unfortunately, we found that the addition of postconditioning to primary PCI had no effect on infarct size and myocardial salvage. In the postconditioning group (n = 53), mean infarct size was 21.1 g versus 20.4 g in the control group (n = 48), and the myocardial salvage index was 16.8 in the postconditioning group and 15.9 in the control group,” said Dr. Traverse. “No benefit of postconditioning was observed when the data was stratified by ischemic times, sex, or age.”

The research team is analyzing follow-up MRIs from these patients taken at 3 months and 1 year. “It is possible that we may see a delayed benefit of postconditioning on LV function since previous studies have not examined this later time point,” explained Dr. Traverse.