Diagnostic and Prognostic Values of the QRS-T Angle in Patients with Suspected Acute Decompensated Heart Failure

AIMS: The aim of this study was to investigate the diagnostic and prognostic utility of the QRS-T angle, an electrocardiogram (ECG) marker quantifying depolarization-repolarization heterogeneity, in patients with suspected acute decompensated heart failure (ADHF). METHODS AND RESULTS: We prospectively enrolled unselected patients presenting to the emergency department with symptoms suggestive of ADHF. The QRS-T angle was automatically derived from a standard 12-lead ECG recorded at presentation. The primary diagnostic endpoint was a final adjudicated diagnosis of ADHF. The primary prognostic endpoint was all-cause mortality during 2 years of follow-up. Among the 1915 patients enrolled, those with higher QRS-T angles were older, were more commonly male, and had a higher rate of co-morbidities such as arterial hypertension, coronary artery disease, or chronic kidney disease. ADHF was the final adjudicated diagnosis in 1140 (60%) patients. The QRS-T angle in patients with ADHF was significantly larger than in patients with non-cardiac causes of dyspnoea {median 110° [inter-quartile range (IQR) 46-156°] vs. median 33° [IQR 15-57°], P < 0.001}. The diagnostic accuracy of the QRS-T angle as quantified by the area under the receiver operating characteristic curve (AUC) was 0.75 [95% confidence interval (CI) 0.73-0.77, P < 0.001], which was inferior to N-terminal pro-B-type natriuretic peptide (AUC 0.93, 95% CI 0.92-0.94, P < 0.001), but similar to that of high-sensitivity troponin T (AUC 0.78, 95% CI 0.76-0.80, P = 0.09). The AUC of the QRS-T angle for discrimination between ADHF and non-cardiac dyspnoea remained similarly high in subgroups of patients known to be diagnostically challenging, including patients older than 75 years [0.71 (95% CI 0.67-0.74)], renal failure [0.79 (95% CI 0.71-0.87)], and atrial fibrillation at presentation [0.68 (95% CI 0.60-0.76)]. Mortality rates according to QRS-T angle tertiles were 4%, 6%, and 10% after 30 days (P < 0.001) and 24%, 31%, and 43% after 2 years (P < 0.001). After adjustment for clinical, laboratory, and ECG parameters, the QRS-T angle remained an independent predictor for 2 year mortality with a 4% increase in mortality for every 20° increase in QRS-T angle (P = 0.02). CONCLUSIONS: The QRS-T angle is a readily available and inexpensive marker that can assist in the discrimination between ADHF and non-cardiac causes of acute dyspnoea and may aid in the risk stratification of these patients.