Predictors of mortality in high-risk patients with QT prolongation in a community hospital

Abstract

Aims: To determine predictors of mortality in patients with corrected QT interval (QTc) ≥ 500 ms in a community hospital.

Methods and results: In this retrospective observational study, we searched the electrocardiogram (ECG) database at Telemark Hospital Trust, Norway, from January 2004 to December 2014. Medication, electrolyte abnormalities, and medical conditions known to prolong the QT interval were recorded. From the medical records, we assessed whether the prolonged QTc was noted by the health care providers. We identified 1531 patients (age = 70 ± 15 years, 59% female) with an ECG with QTc ≥ 500 ms. All-cause mortality during 952 (range 0-4161) days of follow-up was 50% (n = 765/1531). Main predictors of mortality were aborted cardiac arrest [hazard ratio (HR) 2.40, 95% confidence interval (CI) 1.44-4.01; P = 0.001], cerebral stroke/head trauma (HR 2.28, 95% CI 1.70-3.05; P < 0.001), and heart failure (HR 1.74, 95% CI 1.43-2.12; P< 0.001). Females with prolonged QTc had better survival compared with males (P = 0.006). We constructed a risk-weighted QTc mortality score. QT prolongation was acknowledged in the medical records in 12% of the cases.

Conclusions: QTc ≥ 500 ms was associated with high all-cause mortality with increased mortality in males compared with females. A new QTc mortality score was constructed to predict mortality. Only a minority of cases with prolonged QTc ≥ 500 ms were acknowledged in the medical records.