Clinical profile and incidence of 36-month cardiovascular events in patients with MINOCA: a regional registry of 126 patients in a tertiary cardiology hospital
Authors: Valente B P , Sanches F B , Monaco M I D , Naranjo G C S , Alves C H M , Menezes M P , Lijeron I J P , Souto M J S , Aguiar M G , Urdan R , Lemos L F M , Vilalva K H , Junior J R C , Helal L , Pavanello R 
Published: November 2023

Abstract

Introduction
Atherosclerotic plaque rupture is the main etiology of acute myocardial infarction (AMI). In 5% to 6% of AMIs, however, no obstructive lesions greater than 50% are observed, which are then classified as MINOCA (Myocardial Infarction with Non-obstructive Coronary Arteries).The paradigm of MINOCA as a benign condition has been revisited in recent years, as reduced survival rates and a higher risk of subsequent AMIs have been observed when compared to control groups.

Purpose
To describe the clinical profile and the risk of cardiovascular outcomes in patients diagnosed with MINOCA in a tertiary cardiology hospital between March 2000 and June 2022.

Methods
In this single-center cohort, all patients meeting the diagnostic criteria for MINOCA with (1) AMI, as follows: (a) no coronary stenosis ≥ 50% in any potential infarct-related artery; and (b) no other clinically overt specific cause for the acute presentation were evaluated with a median follow-up of 30(9.5-67.3) months. Information was obtained by medical chart. Sample characteristics were described in frequencies and median values(p25%-p75%). The incidence of a new cardiovascular event within 36 months after the MINOCA was estimated using the Kaplan-Meier method and the log-rank test applied to compare groups, accompanied by confidence intervals at 95% and an alpha of 5%(R 3.6.1 for MacOS).

Results
Of the 126 patients, 57.1% were women about 50 years of age (42.0-57.8). 20.6% had diabetes, 47.6% dyslipidemia, 60.3% hypertension and 20% a previous AMI. The predominant clinical presentation was NSTEMI (55.6%) (Table 1), and 7 patients had an episode of aborted sudden death during hospitalization. 38.1% of patients did not have an identified etiology. The most prevalent pathophysiological mechanism was plaque disruption (16.7%), followed by coronary thromboembolism (13.5%) and spontaneous coronary dissection (SCAD) (13.5%). Among the less frequent causes, we had vasospasm (7.1%) and myocardial bridge (2.4%). Only 3.2% underwent optical coherence tomography (OCT) or intravascular ultrasound (IVUS). No provocative testing was performed. 44.4% underwent cardiac magnetic resonance (CMR), within a median time to perform of 180.0 (60.0-707.5) days after the event. Regarding the discharged medical therapy, 79.4% had a beta-blocker and ACEI/ARB prescribed, 14.3% started anticoagulation and only 34.1% received DAPT. The incidence of a composite outcome (CV death, new AMI, stroke and cardiovascular hospitalization) at 36 months was 15% (CI95% 8.9%-24.6%)(Figure 2). The incidence of new MI was 6.3%(N=8), of stroke 2.4% (N=3), and of cardiovascular hospitalization 17.5%(N=22), with only one death.

Conclusion
The risk of the primary outcome in 36 months is worthy of note. Notably, most of the incidence was attributable to CV hospitalization. An important number of patients were discharged without a known etiology for their clinical presentation, and, consequentially, lacked individualized treatment.Figure 1.Outcomes