Medical therapy for secondary prevention in patients with myocardial infarction with non-obstructive coronary artery disease: long-term outcome of a Portuguese centre

Abstract

Abstract Background The outcomes of dual anti-platelet therapy (DAPT), β-blocker, renin-angiotensin-aldosterone system (RAAS) inhibitor and statin therapy are unknown in patients with myocardial infarction with non-obstructive coronary arteries (MINOCA). The aim of this study was to examine the effects of secondary prevention therapy at discharge on long-term outcomes in MINOCA. Methods Patients with MINOCA undergoing early coronary angiography between 2009 and 2016 were extracted from a clinical database. Patients were followed until 2018 for outcome events. All patients with a MINOCA diagnosis and without history of atrial fibrillation were included. A total of 646 consecutive patients were enrolled. The primary end point was major adverse cardiac events (MACE) defined as all-cause mortality, myocardial infarction (MI), stroke, and heart failure (HF). Secondary endpoints comprised all individual endpoints for the composite end-point. The relationship between treatments and outcomes was evaluated by using Kaplan-Meier survival analysis and Cox regression models. Results Mean age was 67.9±13.4 years and 31.6% were women. No patient was lost to follow-up. Mean left ventricular ejection fraction was 47.8±13.1%. At discharge, 87.2%, 82.5% and 79.5% of the patients were on statins, RAAS inhibitors and β-blockers, respectively. The majority (72.8%) were discharged on DAPT. During follow-up (Mdn 59 months), 303 (46.9%) patients experienced a MACE and 208 (33.4%) died. MI occurred in 98 patients (17.8%) and stroke in 31 patients (5.6%). HF admissions were also common (82, 14.9%). The hazard ratio (HR) for major adverse cardiac events was 0.31 (0.23–0.41) in patients on statins, RAAS inhibitors and β-blockers. For patients on DAPT the HR was 0.61 (0.48–0.78). In univariate Cox regression analyses, a reduced risk of MACE was found in patients using combined secondary prevention therapies (HR 0.58, 0.46–0.74). Regarding the individual endpoints, combined secondary prevention therapy reduced the risk of stroke (HR 0.45, 0.22–0.99, P=0.04) but not risk of future MI nor HF admissions. Patients in the combined therapy group had a higher median survival (66 months, IQR 27–82 months) than the group without secondary prevention (34.5 months, IQR 6.8–74 months; P<0.001 of Log Rank test for equality of survivor functions). In a multiple Cox regression analysis including RAAS inhibitors, statins, DAPT and β-blockers in the model, none of these drugs was associated with lower MACE, except for RAAS inhibitors. Conclusions The results indicate long-term beneficial effects of treatment with secondary prevention medical therapies in patients with MINOCA. Properly powered randomized clinical trials are warranted. Funding Acknowledgement Type of funding sources: None.