The relationship between mechanical dyssynchrony of the left ventricular myocardium and the degree of coronary artery occlusion in patients with coronary artery disease

Abstract

Background. The prevalence of chronic heart failure in the world is increasing; however, it is stabilizing in developed countries. One of the reasons for this stabilization is an improvement of acute coronary syndrome treatment and revascularization. Revascularization in patients with chronic coronary syndromes without signs of the left ventricular dysfunction is less effective. One of the promising methods for assessing left ventricular dysfunction is the detection of electrical and mechanical dyssynchrony of the myocardium (DM). However, mechanical dyssynchrony of the myocardium has not been sufficiently studied in patients with coronary artery (CA) disease. The purpose was to assess the relationship between mechanical myocardial dyssynchrony and the degree of coronary artery occlusion in patients with coronary artery disease who underwent revascularization. Materials and methods. One hundred and thirty-four patients with coronary artery disease (35 with myocardial infarction and 99 with chronic coronary syndromes) who underwent coronary angiography and revascularization of coronary arteries were included in the study. According to the results of coronary angiography, patients were divided into 3 groups: 12 had unchanged CA (group 1), 17 had atherosclerotic lesions of CA without signs of occlusion (group 2), and 105 patients were with CA occlusion. Among those with CA occlusion, 10 people had an occlusion of less than 50 %, 26 patients had occlusion from 50 to 80 %, 36 had more than 80 %, and 33 patients had complete occlusion of at least one coronary artery. In all patients, parameters of mechanical DM were determined by ultrasound method. Results. In the first group, 3 patients (25 %) had mechanical DM, in the second — 4 patients (23.5 %), in the group with coronary artery occlusion, 42 patients (40 %) had mechanical DM. In the group with complete CA occlusion, mechanical DM was detected in 18 (53 %) cases. Septal to posterior wall motion delay (SPWMD) did not differ significantly in the comparison groups; however, it increased significantly to 64.8 ± 43.2 ms in patients with complete CA occlusion compared with 40.8 ± 13.1 ms in the group with unchanged CA (p < 0.05). SPWMD had a significant correlation with the degree of CA occlusion (r = 0.254, p = 0.009). The interventricular mechanical delay increased significantly, to 61.3 ± 40.5 ms compared with 33.4 ± 3.4 ms in patients with unchanged CA (p < 0.05). Left ventricular filling time was significantly shorter in the group with complete CA occlusion compared to the patients with incomplete CA occlusion and those with unchanged CA (47.3 ± 10.4 ms vs. 54.2 ± 5.7 ms, respectively; p < 0.05). Left ventricular ejection time was not significantly different between comparison groups, but correlated significantly with the degree of CA occlusion (r = 0.241, p = 0.013). The early ventricular time deceleration, the time from the beginning of the QRS complex to the beginning of the peak systolic velocity did not differ significantly. The time to the peak systolic velocity was significantly longer in the group with complete CA occlusion (32.6 ± 8.5 ms), and had a significant correlation with the degree of CA occlusion (r = 0.26, p = 0.007). Conclusions. A third of patients with chronic coronary syndrome included in the study had DM. In the group with complete CA occlusion, the frequency of DM detection increased significantly and was diagnosed in half of cases. In patients with complete CA occlusion, DM manifested itself in a significant SPWMD, an increase in the period of pre-ejection into the aorta and, as a result, a significant increase in the interventricular mechanical delay. An increase in the time to peak systolic velocity was also found in the group of patients with complete CA occlusion. DM associated with left ventricular diastolic dysfunction was detected in a group of patients with complete CA occlusion and manifested itself in a reduced left ventricular filling time.