Cardiac arrhythmia following acute myocardial infarction: a retrospective analysis of 27,648 hospitalized patients in a tertiary heart hospital

Arrhythmia frequently complicates acute myocardial infarction (AMI) and contributes to high morbidity and mortality. We aimed to investigate the prevalence, risk factors, and impact of cardiac arrhythmias in AMI patients at a tertiary heart hospital. This retrospective observational study included AMI patients who were admitted between January 1991 and May 2022. Patients' data were analyzed and compared according to the absence or presence of cardiac arrhythmias post-AMI. We hypothesized that arrhythmias are associated with higher mortality following AMI. During the study, 27,648 patients were hospitalized with AMI, of whom 2118 (7.7%) developed arrhythmia. Patients who developed arrhythmia had a higher average age compared to those without arrhythmia (57.2 vs. 54.8 years, p=0.001), and a larger proportion were male compared to female patients (85.2% vs. 14.8%, p=0.001). Atrial fibrillation was observed in 383 patients (18.1%). Ventricular tachycardia was found in 461 (21.8%), and ventricular fibrillation occurred in 526 patients (24.8%). Complete heart block was developed in 286 (13.5%) patients, 1st-degree atrioventricular (AV) block in 36 (1.7%), 2nd-degree AV block in 138 (6.5%), left bundle branch block in 81 (3.8%), and right bundle branch block in 118 (5.6%). The rate of β-blocker use has increased in the arrhythmias group at discharge compared to the on-admission rate (55.7% vs. 32.5%). However, it remained sub-optimal. Arrhythmias were associated with longer hospital stays and five times higher hospital mortality than the non-arrhythmia group. Multivariable logistic regression analysis indicated that arrhythmia was associated with increased mortality risk three times following AMI (adjusted odds ratio 3.01; 95% confidence interval 2.42-3.75, p=0.001). Almost one-tenth of patients hospitalized with AMI in Qatar developed arrhythmia with variable outcomes; however, the in-hospital mortality remained high. Addressing the risk factors and optimizing the prevention and treatment of AMI and arrhythmias is crucial to improving clinical outcomes. This study may underestimate the incidence of arrhythmias post-AMI as it did not report all types.