P879Discharge medication and 1-year outcomes in patients with myocardial infarction and nonobstructive coronary artery disease: a nationwide registry-based study

Introduction Myocardial infarction with nonobstructive coronary arteries (MINOCA) occurs in 5% to 10% of all patients with myocardial infarction. Although these patients are often treated as if they had obstructive coronary artery disease (OCAD), optimal medical therapy for secondary prevention in MINOCA patients have not been prospectively studied. We hypothesize that the same treatment strategy as for OCAD is unlikely to be beneficial in MINOCA patients due to their heterogeneous nature. Purpose Characterize and assess the impact of discharge medication on 1-year mortality or hospitalization in patients with MINOCA. Methods Retrospective cohort study of consecutive patients with acute myocardial infarction (AMI) recorded in the Portuguese Registry of Acute Coronary Syndromes (ProACS) between 2010 and 1017. All patients who underwent coronary angiography and had no obstructive lesions (defined as <50% diameter stenosis) were included for analysis (n=829, 4.8% of a total of 17213). Patient demographics, clinical characteristics and medication at discharge were analyzed. The association between treatment and outcome was estimated by comparing treated and untreated groups using Cox proportional hazard models. The exposures considered were treatment at discharge with statins, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ACEi/ARBs), beta-blockers (BB), aspirin (ASA) or dual antiplatelet therapy (DAPT). The outcomes evaluated were 1-year all-cause mortality and 1-year hospitalization due to cardiovascular disease (CVD) Results 829 patients (54% male, mean age 65±13 years) were included. 67% had hypertension, 20% diabetes mellitus, 45% hyperlipidemia, 66% were overweight, 23% were current smokers, 5.5% had history of heart failure, 4.3% valvular heart disease, 8% cerebrovascular disease and 4.7% chronic kidney disease. The admission diagnosis was most frequently non-ST elevation MI (79.3%) and mean left ventricular ejection fraction (%) was 56±12. 4 patients died during hospitalization (0.5%). At discharge, aspirin was prescribed in 85.7% patients, clopidogrel in 54.8%, ticagrelor in 7.5%, DAPT in 57.7%, ACEi/ARB in 79.2%, beta-blocker in 69% and statins in 90.2%. 1-year mortality and 1-year CVD hospitalization was 3.8% and 9%, respectively. After adjusting for covariates in Cox regression analysis, we found no association between any medication at discharge and 1-year outcomes. Conclusion A high proportion of patients are prescribed antiplatelet therapy, including DAPT. We found no significant 1-year beneficial effect of treatment with statins, ACEi/ARBs, BB, aspirin or DAPT in MINOCA. This may be partially explained by the highly heterogenous population and relative short-term follow-up. In MINOCA patients, treatment should be individualized after an exhaustive diagnostic workup to identify the underlying cause (e.g. CAD with spontaneous autolysis of an intracoronary thrombus, myocarditis or takotsubo syndrome).