In-hospital evolution of conduction disorders in acute myocardial infarction in the SAC-FAC National Registry of Infarction

Abstract

Introduction: Despite advancements in the treatment of infarction, the prognosis of those who survive the acute phase depends on factors such as age, heart failure, ventricular function and sex, among others. Previous studies showed higher mortality in patients with conduction disorders during infarction. Objetive: To evaluate the incidence and in-hospital evolution of conduction disorders in myocardial infarction (AMI). Material and methods: Prospective, observational, multicenter study in the Argentina Republic carried
out in 247 centers (all provinces and CABA) including a total of 1759 pts. with a diagnosis of STEMI up to 36 hours of evolution, carried out from March to December 2015. The patients were separated into 4 groups based on the presence of LBBB and right on the ECG of admission and 24 hours: Group I: no abnormalities driving (TC); Group II, Transient: TC only in ECG of admission; Group III, Recent: no CT on admission but present at 24 hours, Group IV: Permanent: CT on admission and 24 hours. Results: In the ECG of admission they presented CRBBB 81 pts (4.6%) and CLBBB 25 pts (1.4%); in the 24-h ECG the CRBBB was evident in 65 pts (3.7%), and CLBBB in 19 (1.1%). Distribution in groups I; II; III and IV for CRBBB was 95.4; 1.5; 0.6 and 2.5%; while for CLBBB it was 98.5; 0.4; 0.1 and 1%. Mortality in the different groups of CRBBB was I: 8.1%, II: 51.9%, III: 18.2% and IV: 7.4% (p <0.001); and of CLBBB: I: 8.4%, II:
85.7%, III: 0% and IV: 22.2% (p <0.001). Killip of II or more at admission in the CRBBB group: group I: 24% (4 pts), group II: 77.8% (21 pts), Group III: 54.5% (6 pts) and group IV: 35.2% (19 pts), (p <0.001); in CLBBB: group I: 25.1% (435 pts) group II: 71.4% (5 pts), group III 0%, group IV 33.3% (6 pts), (p <0.001). Cardiogenic shock: in CRBBB: group I: 7.6% (127 pts), group II: 37% (10 pts), group III: 18.2% (2 pts), Group IV 14.8% (8 pts), p (<0.001); in CLBBB: group I: 8.1% (141 pts), group II 57.1% (4 pts), group III: 0% Group IV 11.1% (2 pts), p (<0.001). Heart failure: in CRBBB: group I: 26.6% (443 pts), group II: 77.8% (21 pts), group III: 54.5% (6 pts), Group IV: 38.9% (21 pts), p (<0.001); in CLBBB: group I: 27.7% (480 pts), group II: 71.4% (5 pts), group III: 0%, Group IV 33.3% (6 pts), p (= 0.06). CRBBB was an independent predictor of mortality OR = 2,250. Conclusions: In the population of patients with acute myocardial infarction, conduction disorders are not frequent, right bundle branch block was present in almost 8.3%; those that were transient and permanent were associated with mortality, and transient ones had greater evolution to HF and cardiogenic shock.