Preventing Torsades de Pointes by Careful Cardiac Monitoring in Hospital Settings:

Assessment of drug-induced torsade de pointes risk for hospitalized high-risk patients receiving QT-prolonging agents

BACKGROUND

Although risk factors for torsade de pointes (TdP) are known, identifying hospitalized patients at greatest risk for QTcP who should receive cardiac monitoring is poorly defined.

OBJECTIVES

Describe the prevalence of risk for TdP in patients and associations between risk factors and QTc prolongation (QTcP) at a tertiary teaching hospital.

METHODS

This retrospective analysis assessed physiological and pharmacological risk factors for TdP of adult patients receiving ≥1 QTc-prolonging medications (QTcMed) during hospitalization. The QTcMeds were stratified by risk for causing TdP (probable, possible, and conditional). Baseline electrocardiograms (ECGs) were assessed for QTcP associated with risk for TdP.

RESULTS

During a 6-month period, 12,401 (51%) hospitalizations received ≥1 QTcMed. A baseline ECG was obtained for 2381 (19%) patients. A total of 386 (16%) patients with a baseline ECG were found to have QTcP. Significant associations for QTcP were found with the following physiological risk factors: female (P = .021), left-ventricular ejection fraction <40% (P < .0001), cardiac arrest (P < .0001), and cardioversion (P = .007). Significantly more patients with QTcP (n = 209, 54%) received probable-risk QTcMeds than those without QTcP (n = 542, 27%; P < .0001). Probable-risk QTcMeds administered alone or concomitantly with other QTcMeds were more frequently associated with QTcP. No documented cases of TdP were identified.

CONCLUSIONS

Of the population receiving QTcMeds, only a small portion had a baseline ECG, identifying a large population at risk of QTcP without appropriate monitoring. Patients with cardiac disease receiving probable-risk QTcMeds were associated with the highest risk of QTcP and should be monitored closely.

[Severe bacterial infection: increased mortality in elderly women with low body weight taking drugs prolonging the QTc interval]

AIMS

Women have a higher risk of acquired long QT syndrome which could be of vital importance in severe bacterial infections when macrolides or fluoroquinolones are administered. This study evaluated whether age, drugs prolonging the QTc interval and body weight were additional influencing factors on mortality in the critically ill with respect to gender.

METHODS

In an exploratory investigation 204 intensive care unit (ICU) patients (78 f, 126 m, 61.1±16.1 years) with severe bacterial infections were studied (mortality probability model II(0) 49.1±28%). Antibiotic therapy was carried out following standard guidelines. In 65.2% of patients potentially QTc prolonging drugs were administered for ≥48 h. Body weight was ascertained on ICU admission.

RESULTS

By comparable severity of illness and comparable effect of antibiotic therapy, age, QTc prolonging drugs and less body weight showed significant effects on survival in women (p<0.001, 0.008 and 0.009, respectively). For women mortality increased with age ≥60 years (p=0.01). The division between survival versus non-survival was intensified by addition of QTc prolonging medication and body weight. As such a best risk assessment in women was achieved if age, QTc prolonging therapy and less body weight were combined (p<0.001). In a direct comparison to men, women with at least two of these factors had a significantly poorer outcome (OR 2.37; 95% CI 1.13-4.98; p=0.022).

CONCLUSIONS

Age, QTc prolonging drugs and lower body weight can additionally increase mortality in critically ill women. If negative outcome is attributed to a higher dosage, an adjustment for body weight must be carried out. Until now it should be considered whether it would be better to replace QTc prolonging antibiotics in routinely performed drug alternation in elderly lean women.