Prolonged QRS associated with left bundle branch conduction defect is a prognostic red flag in asymptomatic patients at risk for heart failure (ACCF/AHA stages A and B): Insights from the DAVID-Berg study

Electrocardiographic abnormalities are often observed in patients with heart failure. One of the most frequent is prolonged QRS duration (QRS> 120ms), with a prevalence ranging from 14% to 47%, increasing in patients with lower left ventricular ejection fraction (LVEF) and higher New York Heart Association class. In patients with heart failure and reduced ejection fraction a prolonged QRS (electrocardiogram (ECG)) has been associated with poor outcome and, along with the presence of left bundle branch block (LBBB), is considered a marker of worse prognosis. Similar findings have been reported in patients with heart failure and preserved LVEF. Indeed, in the I-Preserve (Irbesartan in Patients with Heart Failure and Preserved Ejection Fraction) trial, those patients with prolonged QRS were more likely to have signs and symptoms of decompensated heart failure. These studies suggest that in symptomatic chronic heart failure patients may exist a direct correlation between QRS duration and structural/functional myocardial abnormalities. As a matter of fact, an ECG vector study of 146 patients with LBBB or right bundle branch block (RBBB) demonstrated that QRS prolongation was associated with myocardial infarction, ventricular hypertrophy and altered strain. Although the authors did not provide any clinical data regarding the study population, it could be inferred that comorbidities, associated with higher risk of myocardial ischaemia and hypertrophy (i.e. diabetes mellitus and hypertension) may have a crucial role in inducing a QRS prolongation. While QRS duration has been extensively investigated in symptomatic heart failure patients, no data have been reported in patients at high risk for heart failure (American College of Cardiology Foundation/ American Heart Association stages A and B). We aimed to assess whether the presence of a prolonged QRS is associated with poor outcome in a clinical setting of patients at high risk for heart failure enrolled in the prospective DAVID-Berg (Detection of Asymptomatic VentrIcular Dysfunction in Bergamo) study. Patients aged 55 to 80 years were screened between January 2008 and May 2009. We selected patients without signs and symptoms of heart failure and with at least one of the following criteria: (a) ischaemic heart disease, as defined by angina pectoris with documented ischaemic changes at stress test, or angiographic evidence of coronary stenosis >70% in