High-grade atrioventricular block in ST-segment elevation myocardial infarction patients: insights of a terciary centre

Background: High-grade atrioventricular block (HABV) is associated with poorer outcomes in the setting of acute coronary syndromes. Limited information is available on the incidence and death associated with HABV in STEMI patients (pts) receiving contemporary treatment. Aim: To evaluate the incidence of HABV and its impact on outcome of STEMI patients, in primary percutaneous coronary intervention era. Methods: We analysed retrospectively 1149 STEMI pts admitted, consecutively, in our coronary care unit, from July of 2009 to June 2014. They were divided in two groups: group 1 – pts without HABV, n=1057, 92%); group 2 – pts with HABV (n=92, 8%). For each group we compared clinical features and adverse events. Primary endpoint was the occurrence of death at 6 months; follow-up was completed in 99,8% of patients. Results: Patients of group 2 were older (62±13 vs 69±15;p<0.001), more frequent women (19% vs 30.4%;p=0.014), had higher prevalence of hypertension (57.3% vs 71.7%;p=0.008) and known aortic stenosis (1.7% vs 6.5%;p=0.002). On admission, group 2 presented more often Killip >1 (18.0 % vs 42.4%;p<0.001), cardiogenic shock (2.9% vs 23.1%;p<0.001), anaemia (20.7% vs 39.8%;p<0.001), renal insufficiency (eGFR<60 ml/min) (20.7% vs 50.6%;p<0,001) and higher prevalence of right systolic dysfunction (5% vs 25%;p<0.001). They required more often aminergic support (7.2% vs 42.4%;p<0.001), intra-aortic balloon pump (4.3% vs 9.6%;p=0.05) and mechanical ventilation (2.6% vs 14.5%;p<0.001). They also had higher prevalence of malignant arrhythmias at first 24h (6.5% vs 14.1%;p=0.017) and in-hospital mortality (3.7% vs 24.2%;p<0.001). Among 2nd group of patients, HAVB was present on admission in 43.5%; 15.2% (n=14) had anterior myocardial infarction (AMI) and 84.8% (n=78) inferior myocardial infarction (IMI). Those with AMI implanted temporary pacemaker more frequently (71.4% vs 60.3%), presented more often KK>1 (71.4% vs 37,2%;p<0.001), left ventricular dysfunction (100% vs 34.8%;p<0.001), but less right ventricular dysfunction (7.1% vs 28.4%;p<0.001). Compared with IMI pts, AMI pts had higher risk of in hospital [OR 9.04, 95% CI (2.87-28.50);p<0.001] and 6-month mortality [OR 10.88; 95% CI (3.33 – 35.53);p<0.001]. After adjusting for different baseline characteristics in multivariate analysis, HABV patients had higher risk of overall 6-month mortality compared to those without HABV [OR 2.18, 95% CI (1.25-3.79),p=0.006]. Conclusion: Besides low incidence of HABV, this complication continues to have a high risk of in-hospital and 6-month mortality and occurring with AMI the risk increases significantly.