Myocardial Infarction With Non-Obstructive Coronary Artery Disease: The Prognostic Role Of Infarct Size Predictors

Abstract Background In patients with Acute Myocardial Infarction (AMI) the levels of cardiac troponin T and absolute neutrophil count have been shown to correlate with infarct scar size and left ventricular ejection fraction (LVEF) as well as conferring a risk for major cardiovascular adverse events (MACE). In the context of myocardial infarction with non-obstructive coronary arteries (MINOCA) the prognostic role of such indicators has never been explored. Purpose To evaluate the prognostic role of known myocardial infarct size indicators in a MINOCA population compared to patients with obstructive AMI (Ob – AMI). Methods Among 1990 patients admitted to our coronary care unit from 2016 to 2019 with AMI, we enrolled 186 consecutive MINOCA patients according to the current ESC diagnostic criteria. We compared troponin peak levels, absolute neutrophil count at the time of hospital admission and LVEF in MINOCA patients versus Ob–AMI. Furthermore we assessed the prognostic value of these indicators. All-cause mortality and a composite end - point of all-cause mortality and myocardial re-infarction were evaluated. The median follow-up time was 19.6±12.9 months. Results MINOCA patients were more frequently females (64,9% vs 35,1%; p<0.001), non-smokers (42,3% vs 61,8%; p<0.001) with a lower prevalence of diabetes (9.9% vs 23.7%; p<0.001) compared to the Ob-AMI population. Conversely, no differences were found in hypertension and dyslipidemia. As far as infarct size predictors are concerned, MINOCA patients showed lower levels of troponin value and absolute neutrophil count measured at the time of hospital admission (1838.27±601.0 ng/L vs 13543±3350.6 ng/L; p<0.001, 6.7±1.36x109/L vs 7.1±1.29x109/L; p=0.001, respectively). Moreover, these patients exhibited a higher LVEF (56.1±10% vs 49.3±11%; p<0.001) as compared to Ob-AMI. Among our MINOCA patients, 13 (10.6%) all-cause deaths and 3 (4.3%) myocardial re-infarction were observed during follow-up. Multivariable Cox-regression model demonstrated that mean troponin level, absolute neutrophil count and LVEF were not independent predictors of MACE (HR = 1.0, 95% CI: 0.9–1.1, p=0.6; HR = 0.96, 95% CI: 0.9–1.1, p=0.187; HR = 0.9, 95% CI: 0.79–1.02, p=0. 12 respectively). Conclusion MINOCA patients show a similar prognosis compared to the worldwide AMI population. However, in this study the outcome in the MINOCA population was not influenced by commonly used infarct size predictors, in contrast to what is observed in Ob-AMI patients. These results once again emphasize both the complexity of MINOCA patients and the importance of a better understanding of the different underlying pathophysiological mechanisms. Funding Acknowledgement Type of funding source: None