Clinical Spectrum and Outcome of Conduction Disturbances in Acute Myocardial Infarction in Thrombolytic Era at a Tertiary Care Centre

Abstract

Introduction: Significant number of deaths in Acute Myocardial Infarction (AMI) is attributed to conduction disturbances. Aim: To determine the incidence, pattern of conduction disturbances and their clinical outcome in AMI. Materials and Methods: This was a hospital-based study conducted at Sher-E-Kashmir Institute of Medical Sciences (SKIMS) Jammu and Kashmir, India, a tertiary care hospital from August 2015 to July 2017, in which a total of 429 patients with diagnosis of AMI were included. There were 89 (20.7%) patients with conduction disturbances, and 340 (79.3%) patients without conduction disturbances. They were examined clinically and Electrocardiography (ECG) and Echocardiography (Echo) and many other relevant routine clinical investigations were done to look for development of conduction disturbances and other complications of MI. Frequency (n) and percentage (%) analysis was done on collected data and Fischer's exact test and Chi-square test was conducted for p-value calculations and checked for significance. Results: Out of 429 patients 358 (83.40%) males and 71 (16.60%) females, mean age 57.6±12.39 years), 219 (51.04%) received thrombolysis. In those subjects with conduction disturbances, Atrioventricular (AV) blocks were found in 54 (12.58%) constituting the maximum subjects, followed by intraventricular blocks in 35 (8.1%). Among AV blocks, complete AV block in 45 (10.48%) with mostly transient nature and in intraventricular blocks where Right Bundle Branch Block (RBBB) 17 (3.96%) were the most common types. Intraventricular blocks were more common in anterior infarction and AV blocks in inferior infarction (p70 years, diabetes and worse Killip class at presentation were independent predictors of conduction disturbances. Temporary pacemaker requirement was more than permanent pacemaker 24 (26.9%) vs 5 (5.6%). Right coronary artery (RCA) was dominant artery among AV blocks, which was statistically significant (p-value 0.003). Mortality was about 12.9% amongst the subjects of Atrioventricular Node block and 25.7% amongst those of Intraventricular Blocks while it was 9.41% amongst the subjects without conduction disturbances (p-value 0.013). Mean duration of stay in the hospital was 7±2 days. Conclusion: Conduction blocks were more common in age >70 years, diabetics, in worse Killip class and in inferior infarction. However, no statistically significant correlation was found between occurrence of conduction blocks and various risk factors like hypertension and smoking.

Keywords

• atrioventricular blocks
• electrical disturbances
• heart attack
• morbidity
• mortality
• thrombolysis