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MIAMI -- Easing the heart out of ischemia in an acute myocardial infarction gradually doesn't help stenting outcomes, a clinical trial showed.
Post-conditioning by pulsing a balloon catheter in 1 minute increments after stenting had no impact on return of full perfusion in the heart or complete resolution of ischemia, Joo-Yong Hahn, MD, of Samsung Medical Center and Sungkyunkwan University in Seoul, South Korea, and colleagues found.
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- Explain that a Korean trial found no benefit for post-conditioning for ST-segment-elevation myocardial infarction (STEMI) patients undergoing percutaneous coronary intervention (PCI) compared with conventional PCI.
- Note that specifically there was no significant improvement in ST-segment resolution, restoration of flow, or a composite outcome of cardiac death, reinfarction, severe heart failure, stent thrombosis, target vessel revascularization, or major adverse cardiovascular events at 1 month.
Mortality, reinfarction, and other clinical events pointed to no advantage of the strategy either, the group reported at the Transcatheter Cardiovascular Therapeutics meeting.
After a long period without oxygen, myocardial tissue suffers further damage when blood rushes back in suddenly, termed reperfusion injury.
It's hoped that ischemic conditioning would mitigate those effects, but prior studies have yielded mixed results for conditioning attempts after percutaneous coronary intervention (PCI), Hahn explained at a press conference.
The failure of this first large-scale trial likely means the end for the post-PCI strategy, explained Ajay Kirtane, MD, of New York-Presbyterian Hospital/Columbia University Medical Center in New York City, who moderated the press conference.
"This is a pretty definitive trial for post-conditioning," he told MedPage Today. "Now with this negative data in 700 patients with a pretty good surrogate endpoint, it'd be hard to imagine a lot of enthusiasm for initiating a new trial."
Still, the trial doesn't rule out a benefit of pre-conditioning done before stenting, Kirtane suggested.
Hahn's POST trial included 700 ST-segment elevation myocardial infarction (STEMI) patients undergoing primary PCI randomized to the conventional procedure or use of post-conditioning.
Post-conditioning was done immediately after restoring coronary blood flow to at least Thrombolysis in Myocardial Infarction (TIMI) grade 2. It involved four rounds of 1 minute of balloon occlusion of the infarct vessel then 1 minute of reflow.
For the primary endpoint, the post-conditioning group didn't achieve a higher rate of complete -- defined as greater than 70% -- resolution of the ST-segment on the electrocardiogram as a marker of ischemia (41% versus 42%, P=0.79).
None of the subgroups showed a greater benefit from post-conditioning either.
Restoration of full perfusion to TIMI grade 3 flow tended to be higher with post-conditioning at 92% versus 88% with conventional care, but the difference wasn't significant at P=0.08. Myocardial blush grade likewise didn't differ significantly between groups.
The 1-month mortality rate was actually 30% higher in the post-conditioning group but without a significant difference (4% versus 3%, P=0.53).
Nor was there any advantage to the strategy in terms of risk of cardiac death, reinfarction, severe heart failure, stent thrombosis, target vessel revascularization, or composite major adverse cardiovascular events at 1 month.
The researchers cautioned that the study wasn't double-blind and the sample size wasn't adequate to make definitive conclusions on clinical outcomes, for which it was underpowered.
Also, the trial excluded some groups of patients that might have stood to benefit from post-conditioning, such as those with hemodynamic instability, cardiogenic shock, or left main disease, they added.
Disclosures
Hahn reported having no conflicts of interest to disclose.
Primary Source
Transcatheter Cardiovascular Therapeutics
Source Reference: Hahn J-Y, et al "Effect of postconditioning on myocardial reperfusion during primary percutaneous coronary intervention" TCT 2012.