Heart remodeling in patients with acute Q-wave myocardial infarction in the presence of left bundle branch block

Abstract

The prevalence of left bundle branch block (LBBB) in the general population is 0.1–0.8 %, and in patients with ST-segment elevation Q-wave myocardial infarction (Q-MI) varies from 1 % to 15 %. The aim - to evaluate the structural and functional features of the heart in patients with acute Q-wave myocardial infarction in the presence of left bundle branch block. Materials and methods. The study involved 60 patients with Q-MI (40 men and 20 women), who were hospitalized in cardiology department for patients with myocardial infarction treatment of Zaporizhzhіa City Emergency and Urgent Care Clinic. Patients were divided into two groups: 40 patients with Q-MI and the LBBB (the mean age was 71.53 ± 1.23 years), 20 patients with Q-MI without LBBB (the mean age was 65.47 ± 2.25 years). Assessment of intracardiac hemodynamics were performed by echocardiography using a “MyLab50” (“Esaote”,Italy) ultrasound system on the recommendations of the American Society of Echocardiography. Results. Patients with acute Q-MI with LBBB were significantly older than patients who had acute Q-MI without LBBB (9.2 %, P < 0.05). Patients with anterior acute Q-MI prevailed among persons with LBBB (75 %). Thickening of the posterior wall (by 9.6 %; P < 0.05), an increase in LVMMI (by 11.2 %; P < 0.05), an increase in end-diastolic size (by 12.9 %; P < 0.05) and end-systolic size (by 18.6 %; P < 0.05); acceleration of MVE (by 18.3 %; P < 0.05); and an increase systolic pressure in the pulmonary artery (by 23.1 %; P < 0.05) were found in patients with Q-MI with LBBB compared to patients with Q-MI without LBBB. The analysis of contingency table revealed significant association between LBBB presence in patients with Q-MI and diabetes mellitus (χ 2 = 4.53; P < 0.05), female gender (χ 2 = 3.87; P < 0.05) and age over 65 years (χ 2 = 5.71; P < 0.05). In patients with acute Q-MI and LBBB a significant positive correlation between the QRS width and end-diastolic size (+0.49; P < 0.05), end-systolic size (+0.45; P < 0.05), systolic pressure in pulmonary artery (+0.31; P < 0.05) and diastolic size of right ventricle (+0.38; P < 0.05), and a negative correlation between the QRS width and ejection fraction (-0.71; P < 0.05) and IVRT (-0.37; P < 0.05) were noted. Conclusions. LBBB in patients with acute Q-MI is associated with female gender, age over 65 years and past history of diabetes mellitus. Acute Q-MI in the presence of LBBB is characterized by eccentric hypertrophy with an increase in the left ventricular size and pulmonary hypertension. QRS complex duration in patients with acute Q-MI and LBBB is associated with systolic function deterioration, left ventricular dilatation and pulmonary hypertension.