Phenotypic profiles of heart failure during acute myocardial infarction and their association with de novo atrial fibrillation

Background

The incidence of new-onset atrial fibrillation (NOAF) in acute myocardial infarction (AMI) ranges widely, reported between 6% and 21% across studies. Its prognostic significance remains controversial, with conflicting evidence on its impact on heart failure and long-term mortality.

Purpose

To evaluate cardiac structural and functional characteristics associated with NOAF during AMI and their relation to 2-year heart failure hospitalization rates.

Methods

This prospective study enrolled 150 adults with AMI within 24 hours of onset. Patients were divided into two groups: 75 with NOAF and 75 maintaining sinus rhythm. Individuals with prior atrial fibrillation, major non-cardiac comorbidities limiting life expectancy, cognitive impairment, or substance abuse were excluded. Clinical, paraclinical, and echocardiographic assessments were performed, patients followed for 2 years to evaluate hospitalizations for heart failure and mortality outcomes.

Results

A total of 150 patients were included (mean age 67.4 ± 10.6 years). Patients with AMI and NOAF were older than those without (70.0 ± 9.9 vs. 64.7 ± 10.6 years, p = 0.001). Sex distribution was similar between groups.

Left atrial (LA) dimensions were comparable between the NOAF and sinus groups, with mean LA of 42.5 ± 5.0 mm versus 41.1 ± 4.5 mm, respectively (p = 0.12). However, LA volume was significantly higher in the NOAF group (59.8 ± 11.8 mL vs. 51.2 ± 10.0 mL; p < 0.001), and indexed LA volume was also elevated (32.9 ± 6.3 mL/m² vs. 26.7 ± 5.5 mL/m²; p < 0.001), with 44% of NOAF patients exceeding 34 mL/m² compared to 14.7% in the sinus cohort (p < 0.001). Right atrial dimensions were similar between groups. Ventricular mass indices were markedly higher in NOAF patients (LV mass 203.0 ± 56.5 g vs. 169.9 ± 56.9 g; LV mass index 112.5 ± 31.4 g/m² vs. 89.4 ± 32.0 g/m²; both p < 0.001), reflecting a predominance of eccentric hypertrophy (37.3% vs. 20.0%) and remodeling. Left ventricular ejection fraction was significantly reduced in the NOAF group (44.3 ± 12.7% vs. 50.5 ± 12.0%; p = 0.005). Categorically, HF with mildly reduced ejection fraction was present in 46.7% of NOAF patients versus 38.7% of sinus patients, and with reduced ejection fraction was observed in 16% versus 1.3%, respectively (p < 0.001).

Analyzing this cohort over a 2-year follow-up, hospitalizations for heart failure (figure 1) occurred in 28.7% of the total population (n = 43; 95% CI: 21–36%), being more frequent in the NOAF group (37.3%; 95% CI: 26–48%), reaching statistical significance (p = 0.030).

Conclusions

Patients who developed NOAF during AMI demonstrated larger left atria, higher ventricular mass, abnormal remodeling, and greater systolic dysfunction compared with those maintaining sinus rhythm. This adverse cardiac phenotype translated into a higher incidence of heart failure hospitalizations over 2 years, highlighting the prognostic impact of NOAF in this population.HF hospitalizations by rhytm statusFor image description, please refer to the figure legend and surrounding text.