Relationship between QRS duration, left ventricular volumes and prevalence of nonviability in patients with coronary artery disease and severe left ventricular dysfunction

Background: Patients with coronary artery disease (CAD), a QRS duration ≥120 ms and left ventricular ejection fraction (LVEF) ≤30% are potential candidates for cardiac resynchronization therapy (CRT). Our aim was to investigate the relationship between QRS duration, left ventricular volumes and prevalence of nonviable tissue in this patient population. Methods: We studied 132 patients (118 men, age 68±5 years) with CAD and LVEF ≤30% (mean LVEF 24±6%). LV volumes and myocardial viability were determined by gated myocardial perfusion imaging. Results: A QRS duration ≥120 ms was present in 91 patients (69%). Although there were no differences in LVEF, patients with longer QRS durations had significant larger end-diastolic and end-systolic volumes (p<0.01). Substantial nonviable tissue in the inferior or lateral wall was present in 29% of patients with a QRS duration ≥120 ms versus 7% of those with a QRS duration <<120 ms (p<0.01). Conclusions: An increased QRS duration is associated with more advanced remodeling in patients with CAD and poor LV function. Almost one third of these patients with a prolonged QRS duration have no viable tissue in the inferolateral wall, an area that is usually stimulated with CRT.