Background: The purpose of this study was to evaluate the influence of thrombus aspiration during primary percutaneous coronary intervention (PCI) on myocardial viability in patients with ST-segment elevation myocardial infarction (STEMI) using cardiac magnetic resonance imaging (MRI).
Methods and results: We performed cardiac MRI in 62 patients who underwent primary PCI for STEMI with manual thrombus aspiration. We divided the patients into two groups: those who had thrombus aspiration during primary PCI, which resulted in a successful procedure (n=47 patients; TA group) and those who had thrombus aspiration and an unsuccessful procedure (n=15 patients; non-TA group). Thrombus aspiration was defined as successful or unsuccessful, based on the histological evidence of atherothrombotic material in the aspirate samples. The infarct volume was quantified using delayed-contrast enhancement on cardiac MRI. The reference volume was defined as transmural myocardial volume at the infarcted segment. Myocardial viability was assessed by a transmurality index defined as the ratio of the infarct volume to the reference volume. Although baseline characteristics and the reference volume were comparable between the two groups (24.5 ± 12.5 ml for TA group versus 29.0 ± 9.6 ml for non-TA group; p = 0.21), the infarct size was significantly smaller in the TA group than in the non-TA group (12.2 ± 7.1 ml versus 17.4 ± 7.1 ml, respectively; p = 0.01). The transmurality index was also significantly lower in the TA group (49.3 ± 10.6% versus 60.9 ± 13.9%, respectively; p = 0.001).
Conclusion: Patients with successful TA showed more reduced infarct size and preserved myocardial viability than patients without TA. These effects of TA may lead to preserved left ventricular systolic function and better clinical outcomes.