Utility of QRS width and echocardiography parameters in an integrative algorithm for selecting heart failure patients with cardiac dyssynchrony.

Background: Cardiac resynchronization therapy (CRT) is an effective treatment in dilated cardiomyopathy (DCM). However, it has been demonstrated that mechanical dyssynchrony is not related to electrical dyssynchrony. We hypothesized that a new QRS width cutoff could be easier to use as a first step in the selection of patients with inter- and intraventricular dyssynchrony.

Methods: We included 58 patients with DCM. Electrocardiographic (PR interval and QRS width) and echocardiographic (left ventricular dimensions, systolic and diastolic function, dyssynchrony parameters) data were evaluated in all patients.

Results: According to QRS width, we divided the study population in two groups: Group 1, 25 patients having a narrow QRS (120 ms). Patients in Group 2 had larger left ventricles, with similar systolic function and more severe diastolic dysfunction than patients with narrow QRS. Interventricular dyssynchrony was more frequent in group 2 (54.5% vs 20%, p=0.01), while intraventricular dyssynchrony was highly prevalent in both groups (82.1% vs 72%, p=0.48). A QRS>140 ms best predicted the presence of interventricular dyssynchrony (sensitivity 78.2% and specificity 63.6%), while a QRS>150 ms best predicts intraventricular dyssynchrony (sensitivity 48.6% and specificity 80%).

Conclusions: Intraventricular dyssynchrony has a high prevalence in patients with DCM, irrespective of the QRS width. Using a higher QRS width cutoff (150 ms) might help in patient selection for CRT. Electrocardiography and echocardiography can be combined into a selection algorithm for patients receiving resynchronization therapy.