دانلود رایگان مقاله رابطه QRS و تشدید تاخیری رزونانس مغناطیسی قلبی

Abstract

Background: We explored the relationship between QRS characteristics and myocardial phenotype by delayed-enhancement cardiac magnetic resonance (DE-CMR) in patients with coronary heart disease (CHD). Methods and results: Eighty five consecutive patients with CHD that were referred for DE-CMR evaluation constituted the study population. Of a total of 1445 left ventricular (LV) segments evaluated, 346 (23.9%) segments had fibrosis. Compared to patients without pathological Q waves, patients with pathological Q waves showed a higher number of segments with fibrosis (5.9
3.1 vs. 2.7
2.8, p < 0.001), and lower left ventricular ejection fraction (LVEF) (42.9
13.6% vs. 51.8
18.3, p Z 0.01); whereas no significant differences were observed regarding LV size. When discriminated in according to the QRS duration tertiles, no significant differences were observed regarding the number of segments with fibrosis (p Z 0.34), whereas the highest QRS tertile was related to the presence of a low LVEF (p Z 0.005) and larger LV size (p Z 0.01). QRS fragmentation (fQRS), defined as the presence of an R0 or notching in the nadir of the R wave or the S wave, or the presence of >1 R0 in 2 contiguous leads, was significantly related to LV size (LV end diastolic volume 153.6
81.6 ml, vs. 111.5
41.4 ml, p Z 0.003), function (LVEF 43.2
15.9% vs. 53.6
16.3%, p Z 0.005), and extent of fibrosis (5.1
3.4 segments vs. 3.2
3.1 segments, p Z 0.01). Conclusions: In the present study, fQRS was the only QRS-derived variable systematically and more closely related to LV size, LV systolic function, and to the presence and extent of fibrosis.

QRS fragmentation

The presence of fQRS has been identified as a predictor of major adverse cardiac events and of SCD in patients with CHD, and has been shown to have a better predictive value than pathological Q waves for the detection of myocardial fibrosis.15,16 The presence of myocardial fibrosis is believed to cause an heterogeneous ventricular activation, leading to fQRS.17 Recently, fQRS in patients with CHD and preserved LV systolic function was related to the presence of subclinical global and regional LV dysfunction, as assessed by strain echocardiography.16 However, the evidence relating fQRS and myocardial fibrosis as assessed by DE is both scarce and controversial.18 In the present study, the presence of fQRS was highly related to LV remodeling, systolic dysfunction, and with the presence and extent of myocardial fibrosis.