Development and Validation of a Risk Score to Predict QT Interval Prolongation in Hospitalized Patients

Abstract

Background Identifying hospitalized patients at risk for QT interval prolongation could lead to interventions to reduce the risk of torsades de pointes (TdP). Our objective was to develop and validate a risk score for QT prolongation in hospitalized patients. Methods and Results In this study in a single tertiary care institution, consecutive patients (n=900) admitted to cardiac care units comprised the risk score development group (DG). The score was then applied to 300 additional patients in a validation group (VG). Corrected QT (QTc) interval prolongation (defined as QTc > 500 ms and/or an increase of > 60 ms from baseline) occurred in 274 (30.4%) and 90 (30.0%) patients in the DG and VG, respectively. Independent predictors of QTc prolongation included: female (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.1–2.0), diagnosis of myocardial infarction [2.5 (1.6–3.9)], sepsis [2.7 (1.5–4.8)], left ventricular dysfunction [2.7 (1.6–5.0)], administration of a QT-prolonging drug [2.8 (2.0–4.0)], ≥ 2 QT- prolonging drugs [2.6 (1.9–5.6)], or loop diuretic [1.4 (1.0–2.0)], age > 68 years [1.3 (1.0–1.8)], serum K+ < 3.5 mEq/L [2.1 (1.5–2.9)], and admitting QTc > 450 ms [2.3; CI (1.6–3.2)]. Risk scores were developed by assigning points based on Log ORs. Low, moderate and high risk ranges of 0–6, 7–10 and 11–21 points, respectively, best predicted QTc prolongation (C statistic = 0.823). A high risk score > 11 was associated with sensitivity = 0.74, specificity = 0.77, positive predictive value = 0.79 and negative predictive value = 0.76. In the VG, the incidences of QTc prolongation were 15% (low risk); 37% (moderate risk); 73% (high risk). Conclusions A risk score using easily obtainable clinical variables predicts patients at highest risk for QTc prolongation and may be useful in guiding monitoring and treatment decisions.

Effectiveness of a Clinical Decision Support System for Reducing the Risk of QT Interval Prolongation in Hospitalized Patients

“…The CDSS incorporated a validated risk score for QT c interval prolongation, 17 and patient information extracted by the CDSS was based on known risk factors for QT c interval prolongation that are included in this risk score. Development and validation of the QT c prolongation risk score have been described previously.…”

“…Development and validation of the QT c prolongation risk score have been described previously. 17 The QT c interval prolongation risk score is presented in Table 2. Serum magnesium concentrations are not included in the score because they were only obtained in 38% of patients admitted to the CCU.…”

“…Patients were classified as being at low, moderate, or high risk of developing QT c interval prolongation during their hospitalization, based on risk scores of <7, 7 to 10, or ≥11, respectively. 17 …”

Complement and sepsis-induced heart dysfunction

“…These ECG changes returned to normal following recovery from septic shock, showing reversible reductions of QRS amplitudes (Rich et al, 2002). Another ECG complication during sepsis is QT prolongation (Tisdale et al, 2013; Varriale and Ramaprasad, 1995). Prolongation of the QT interval was a negative predictive factor in septic patients (Tisdale et al, 2013).…”

“…Another ECG complication during sepsis is QT prolongation (Tisdale et al, 2013; Varriale and Ramaprasad, 1995). Prolongation of the QT interval was a negative predictive factor in septic patients (Tisdale et al, 2013). ECG from human with sepsis also reported myocardial depression and takotsubo syndrome (TS), which the latter may be the cause of the majority of cases of sepsis-induced myocardial depression (Y-Hassan et al, 2014).…”