Collections > Master's Papers > Gillings School of Public Health > A Model for Remote Ischemic Conditioning in Prehospital ST-Elevation Myocardial Infarction Patients: A Systematic Review

Acute myocardial infarction is treated regularly with emergency coronary intervention, but this treatment comes with the risk of reperfusion injury. Remote ischemic conditioning (RIC) is a treatment that has the potential to reduce the impact of reperfusion injury, but it is unclear what effect it has on patients diagnosed with ST-elevation myocardial infarction (STEMI) when used before cardiac intervention. This systematic review was performed to identify and evaluate studies that assess whether RIC improves mortality, reduces myocardial injury, and leads to better clinical outcomes when used in patients at risk for reperfusion injury. Searches were performed in PubMed, EMBASE, and through April 2018 for clinical trials comparing RIC and standard care before patients with STEMI receive ether percutaneous coronary intervention (PCI) or thrombolytic intervention. Outcomes considered in this review include all-cause mortality, infarct size, ST-segment resolution, cardiac biomarker trends, left ventricular ejection fraction, and myocardial salvage index. One investigator selected qualifying trials, extracted data, and assessed the strength of evidence.Eleven studies (2,981 participants) were included in this review and most were found to demonstrate a low risk of bias. Evidence was found to be of moderate strength for four outcomes (all-cause mortality, infarct size, left ventricular ejection fraction, and myocardial salvage index), low strength for one outcome (ST-segment resolution), and very low strength for one outcome (cardiac biomarker trends). All-cause mortality was the only outcome for which the evidence showed no difference between RIC and standard care. Significant decreases in infarct size, when measured directly through imaging, was moderate, ranging from 2% to 6.5%, but varied widely when infarct size was measured using ST-segment resolution and cardiac biomarker trends as proxies. Myocardial salvage index was consistently shown to be improved in RIC patients but varied in magnitude from 8.7% to 50% higher median index scores. Most studies found higher left ventricular ejection fractions with magnitudes ranging from 2.6% to 10%. The evidence synthesized here shows that RIC improves intermediate cardiac outcomes but has not been shown to improve all-cause mortality.