LAUSR

Background: Complete heart block (CHB) is a medical emergency and usually requires immediate intervention. Either cardiac ischemia or non-ischemic conditions can cause CHB. Aim: To compare baseline clinical characteristics associated with ischemic versus non-ischemic causes of CHB and their outcomes. Materials and Methods: This was a single centre retrospective, observational study. Consecutive 250 patients with CHB from January-December 2016 were included. Patients were characterized into non-ischemic and ischemic groups based on cardiac marker elevation, electrocardiogram changes and/or cardiac catheterization findings. In all patients, demographics, pre-existing comorbidities, prior use of nodal blocking agents and ejection fraction (EF) were recorded. The primary outcome was all-cause mortality and secondary outcome was pacemaker implantation. Statistics Analysis: Mean and standard deviation were calculated for all continuous variables. Percentages were calculated for all categorical variables. Unpaired student’s ‘t’ test was utilized to find out the difference between means and to calculate the significance level and p-value. RESULTS: Out of 250 patients, 137 had ischemic and 113 had non-ischemic CHB. The mean age was 60.54 years in ischemic group and 61.32 years in the non-ischemic group (p=0.58). Patients with ischemic CHB had a lower mean EF [44.2%v/s 55.2% (p<0.01)]. In the ischemic group 55 patients (40%) presented with cardiogenic shock compared to 6 (0.07%) in the non-ischemic group (p<0.001). There was no statistically significant difference in terms of gender, hypertension, thyroid dysfunction, prior usage of nodal blocking agents and electrolytes and statistically significant difference was present between ischemic and non ischemic groups in diabetes mellitus (DM) (56.9% vs 45%p=0.006), dyslipidaemia (13.1%vs0.5%p=0.001) and smoking (31.3%v/s14.1%p<0.001). In the ischemic group 112 patients had inferior wall myocardial infarction (IWMI) (81.7%) and 21 had anterior wall myocardial infarction (AWMI) (15.3%). RCA was the most common culprit vessel (73%). Seventy patients underwent percutaneous coronary intervention and 10 were referred for CABG. For outcomes,8 out of 113 (0.07%) patients with non-ischemic CHB died compared to 33 out of 137 (24.1%) ischemic CHB (p<0.001). Permanent pacemaker (PPI) was implanted in 76 out of 113 patients (67.2%) in the non-ischemic group compared to 14 out of 137 (10.2%) in the ischemic group (p<0.001). Out of the patients who underwent PPI, 9 had AWMI and 5 had IWMI. Conclusion: Patients with ischemic CHB have lower mean EF with majority having IWMI and had higher mortality. Risk factors like DM, dyslipidaemia and smoking are more frequent in the ischemic group and they are less likely to get a permanent pacemaker compared to non-ischemic CHB. In the ischemic group patients with AWMI got more PPI than IWMI.