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Abstract

Background: Acute Myocardial Infarction (AMI) remains a critical cardiovascular emergency frequently associated with conduction disturbances, including Right Bundle Branch Block (RBBB). The sudden onset of RBBB during AMI not only complicates electrocardiographic interpretation by masking ischemic changes but may also correlate with worse clinical outcomes such as arrhythmias and heart failure. Despite its clinical importance, limited local data exist regarding the frequency and characteristics of new-onset RBBB among AMI patients, highlighting a gap in regional cardiac research.
Objective: To determine the frequency of new-onset Right Bundle Branch Block in patients presenting with Acute Myocardial Infarction.
Methods: This descriptive cross-sectional study was carried out at the Department of Cardiology, Lady Reading Hospital, Peshawar, over a six-month period. A total of 131 patients aged 18 to 60 years, diagnosed with AMI based on standardized criteria, were enrolled using non-probability consecutive sampling. Patients with previously diagnosed RBBB, cardiac surgery, electrolyte abnormalities, or pregnancy were excluded. Standard 12-lead ECGs were performed on admission, and RBBB was identified by a QRS duration >120 milliseconds and an rSR′ pattern in lead V1. Data were analyzed using SPSS version 26, with chi-square or Fisher’s exact test applied for stratification. A p-value <0.05 was considered statistically significant.
Results: Among 131 AMI patients, 19 (14.5%) exhibited new-onset RBBB. Stratified analysis showed RBBB in 11 of 87 males (12.6%) and 8 of 44 females (18.2%) (p=0.41), and in 13 of 82 patients >50 years (15.9%) versus 6 of 49 aged ≤50 years (12.2%) (p=0.57). Diabetics showed a frequency of 17.6% compared to 12.5% in non-diabetics (p=0.43), while hypertensives had a rate of 16.7% versus 11.3% in non-hypertensives (p=0.47). No statistically significant associations were observed across BMI, socioeconomic class, or residential status.
Conclusion: New-onset RBBB was observed in a clinically relevant portion of AMI patients. Although no significant associations were found with baseline variables, the patterns suggest a possible link warranting further exploration in larger, outcome-based multicenter studies.