Impact of smoking in MINOCA patients.

Background: Considerable research has been conducted in recent years on patients afflicted with myocardial infarction with nonobstructive coronary disease (MINOCA), focussing on its prognosis, prevalence and predisposing risk factors. Nevertheless, there remains a dearth of information regarding the baseline characteristics and outcomes of MINOCA patients with a history of smoking. This study endeavours to examine the in-hospital complications and baseline characteristics of a presumed MINOCA cohort comprising individuals with a history of smoking.

Methods: In this study, a total of 373 patients (85 current smokers and 283 non-smokers), who exhibited elevated troponin levels but had no evidence of obstructive coronary artery disease, were enrolled between 2010 and 2021. MINOCA patients had to fulfil the modified criteria for acute myocardial infarction (AMI) based on the 'Fourth Universal Definition of Myocardial Infarction', including an up- or downregulated troponin level with at least one value exceeding the 99th percentile, along with clinical evidence of infarction (e.g. ischaemic ECG changes, myocardial damage or coronary thrombus). Additionally, patients with less than 50% stenosis of a major epicardial vessel without intervention and those with alternative diagnoses mimicking troponin-positive nonobstructive coronary disease were excluded. It should be noted that there were five patients for whom data regarding smoking status were not available. The primary objective of this investigation was to evaluate the occurrence of various in-hospital events, including pulmonary oedema, invasive ventilation, cardiogenic shock, stroke, cardiopulmonary resuscitation, malignant cardiac arrhythmias, supraventricular arrhythmias, left ventricular thrombus, thromboembolic events and in-hospital mortality. Additionally, long-term cardiovascular events were assessed over an 11-year follow-up period.

Results: Baseline demographics in smokers and non-smokers showed notable differences in the prevalence of supraventricular arrhythmia, particularly atrial fibrillation (5.8% vs. 17.4%; p = .020), diabetes mellitus (DM) (10.5% vs. 19.7%; p = .051), kidney disease (9.3% vs. 15.9%; p = .075) and chronic obstructive pulmonary disease (COPD) (18.6% vs. 10.8%; p = .057). The occurrence of in-hospital cardiovascular events and mortality rates was found to be comparable between smokers and non-smokers. However, non-smokers experienced a higher incidence of long-term cardiovascular events compared to smokers. A multivariable Cox analysis for long-term outcomes indicated that individuals under the age of 50 who were smokers had a more favourable outcome. Nonetheless, the presence of DM, supraventricular tachycardia, pulmonary disease and neurological disease were all associated with a diminished long-term prognosis.

Conclusion: Although the long-term health outcomes for smokers are comparatively superior to those of non-smokers, this contrast can be attributed to the increased incidence of cardiovascular comorbidities and the older age distribution within the non-smoking population.