NHLBI-Sponsored Postconditioning Study Shows Delayed Benefit for STEMI Patients
Minneapolis, Minn. — January 14, 2019 — The first National Heart, Lung, and Blood Institute (NHLBI)-sponsored trial of postconditioning (PostC) in the United States found that following PostC, patients with ST-elevation myocardial infarction (STEMI) exhibit reduced microvascular obstruction (MVO) in the infarct zone and improved left ventricular remodeling compared to control at one year as assessed by cardiac magnetic resonance imaging (MRI). The clinical trial, published Jan. 3, 2019, online at Circulation Research, from the Minneapolis Heart Institute Foundation® (MHIF) and Abbott Northwestern Hospital (Minneapolis, Minn.,) observed that the early benefits of PostC were not seen in the days after heart attack, but rather, only became apparent during long-term follow-up.
“These findings may have significant implications for improving the long-term outlook for the nearly 250,000 patients each year who experience STEMI,” said Dr. Jay Traverse, principal investigator of the study. “When utilized during successful primary angioplasty and stenting, PostC may help patients’ hearts function better over time, with less enlargement. This could potentially reduce the patients’ risk of developing heart failure, which is the most common cause for hospital admission in the U.S.”
The standard treatment following a heart attack is primary percutaneous coronary intervention (PCI), with stenting to open the blocked artery. When PostC is used at the same time, cardiologists perform several sequential balloon inflations and deflations during the initial phase of blood flow restoration. This is thought to reduce reperfusion injury, which can minimize the extent of heart muscle damage. While PostC has previously been shown in animal models to significantly reduce infarct size and improve myocardial salvage, clinical trials have not consistently demonstrated a similar benefit in humans when measured by cardiac MRI several days after the procedure.
“Our findings suggest that the early benefits of PostC may not be readily apparent, and therefore long-term clinical and imaging follow-up should be performed in these patients,” said Dr. Traverse.
Study Protocol and Results
The randomized MHIF study of 122 STEMI patients with an occluded major epicardial artery utilized strict enrollment criteria to optimize the early benefits of PostC and assess its long-term effects on left ventricular function. Sixty-five patients received PostC (four 30-second balloon inflations/deflations) plus primary PCI, while 57 patients in the control group received PCI alone. Patients were required to 920 East 28th Street, Suite 100 Minneapolis, MN 55408 (612) 863-3833 mplsheart.org
have ischemic times between one and six hours and no evidence of pre-infarction angina or collateral blood flow. All patients underwent cardiac MRI prior to discharge on Day Two.
On baseline MRIs, the average infarct size was 16.4 percent of left ventricular (LV) mass with an average ischemic time of 150 minutes and 42 percent of patients had MVO. Mean left-ventricular ejection fraction (LVEF) measured the day after PCI was 49 percent.
The investigators found that PostC did not reduce infarct size (22.5 vs. 24 g.) or improve myocardial salvage compared to the control group (30.3 vs. 31.5 percent) when measured two days after PCI. However, at their 12-month follow-up MRI, patients randomized to PostC experienced much more favorable remodeling.
Left-ventricular end-diastolic volume (LVEDV) increased in the control group (157 to 165 ml), but decreased in the PostC group (157 to 150 ml; p < 0.05) where a significant decline in LV end-systolic volume (70 to 58 ml; P < 0.05) was also observed.
“These changes may be related to a beneficial effect of PostC on the development of MVO, which was significantly reduced in the PostC group,” said Dr. Traverse. “MVO is known to be associated with impaired recovery of the heart’s function. Perhaps PostC attenuates reperfusion injury in the microvasculature, making it less susceptible to the development of MVO,” said Dr. Traverse.
About the Minneapolis Heart Institute Foundation
The Minneapolis Heart Institute Foundation (MHIF) strives to create a world without heart and vascular disease. To achieve this bold vision, it is dedicated to improving the cardiovascular health of individuals and communities through innovative research and education.
- • Scientific Innovation and Research — MHIF is a recognized research leader in the broadest range of cardiovascular medicine and population health initiatives. Each year MHIF leads more than 175 active research projects and publishes more than 120 peer-reviewed studies. Cardiologists, hospitals and communities around the world adopt MHIF protocols to save lives, improve care and create healthier living opportunities.
- • Education and Outreach — MHIF provides more than 10,000 hours of education each year putting its research into practice to improve outcomes. And, MHIF leads cutting-edge, transformative population health research to connect, engage, inform and empower individuals and communities to improve their health.
The Minneapolis Heart Institute Foundation’s work is funded by generous donors and sponsors and supports research initiatives of Minneapolis Heart Institute® at Abbott Northwestern Hospital. Minneapolis Heart Institute® physicians provide care for patients at Abbott Northwestern Hospital in Minneapolis and at 38 community sites across Minnesota and western Wisconsin.