Abstract 18737: Prevalence and Outcome of Patients With Idiopathic QT Prolongation Identified Through an Institution-Wide QT-Alert System
Background: Since QT prolongation is a risk factor for sudden death, stroke, and all-cause mortality, we developed an electronic, institution-wide QT alert system to identify patients with significant QT prolongation (i.e. QTc≥500 ms if QRS <120 ms). These patients encountered a significant increased mortality within 1 year, and nearly 40% of patients with ≥4 QTc inciting factors have died. Herein, we examined the patients with ≤1 identifiable QTc inciting factor.
Methods: Between November 2010 and June 2011, 53,732 patients underwent ECG-evaluation, 1,145 QT-alerts (2.1%) were triggered, and 470 of the QT-alerted patients had ECG-isolated QT prolongation. Clinical, laboratory, and therapeutic information were collected. Excluding female gender and bradycardia, other potential QT inciting factors (drugs, electrolyte disturbances, and co-morbidities) were synthesized into a pro-QT score and patients with a score of ≤1 were compared to patients with a pro-QT score >1.
Results: About one-third (N=150, 59% female) of this QT-alerted cohort had a pro-QT score of ≤1 including 42 patients with an established diagnosis of congenital long QT syndrome (LQTS). Excluding LQTS patients, the remaining 108 patients (60 female, age 59±25 years) were significantly more likely to have a QT prolonging cardiovascular co-morbidity (44%) than those with a QT-score >1 (29%; p=0.006). However, mortality was similar between those with a QT-score ≤1 (19%) and those with a QT-score >1 (27%, p=0.09). Fourteen patients (9 female; age 64±22 years; QTc 507±14 ms) had no discernible QT inciting factors (i.e. pro-QT score=0) including 6 patients with previously documented QT prolongation.
Conclusions: Only a minority of patients with ECG-isolated QT-prolongation (~3%) had no discernible QT-inciting factors other than female gender in 9. Careful scrutiny of these patients with seemingly idiopathic QT prolongation may identify novel QT provoking conditions. Alternatively, considering that 14 of 53,732 patients (1 in 3888) activated the alert system without obvious QT inciting factors and that congenital LQTS has an estimated prevalence of 1 in 2000, it is possible that this universal QT alert system has caught patients with yet to be diagnosed LQTS.
- © 2013 by American Heart Association, Inc.