Relationship between QRS characteristics and delayed-enhancement cardiac magnetic resonance in patients with ischemic cardiomyopathy

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 = 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 = 0.34), whereas the highest QRS tertile was related to the presence of a low LVEF ( p = 0.005) and larger LV size ( p = 0.01). QRS fragmentation (fQRS), defined as the presence of an R′ or notching in the nadir of the R wave or the S wave, or the presence of >1 R′ 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 = 0.003), function (LVEF 43.2 ± 15.9% vs. 53.6 ± 16.3%, p = 0.005), and extent of fibrosis (5.1 ± 3.4 segments vs. 3.2 ± 3.1 segments, p = 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.