High prevalence of corrected QT interval prolongation in acutely ill patients is associated with mortality: results of the QT in Practice (QTIP) Study.

OBJECTIVE: To test the potential value of more frequent QT interval measurement in hospitalized patients. DESIGN: We performed a prospective, observational study. SETTING: All adult intensive care unit and progressive care unit beds of a university medical center. PATIENTS: All patients admitted to one of six critical care units over a 2-month period were included in analyses. INTERVENTIONS: All critical care beds (n = 154) were upgraded to a continuous QT monitoring system (Philips Healthcare). MEASUREMENTS AND MAIN RESULTS: QT data were extracted from the bedside monitors for offline analysis. A corrected QT interval >500 msecs was considered prolonged. Episodes of QT prolongation were manually over-read. Electrocardiogram data (67,648 hrs, mean 65 hrs/patient) were obtained. QT prolongation was present in 24%. There were 16 cardiac arrests, with one resulting from Torsade de Pointes (6%). Predictors of QT prolongation were female sex, QT-prolonging drugs, hypokalemia, hypocalcemia, hyperglycemia, high creatinine, history of stroke, and hypothyroidism. Patients with QT prolongation had longer hospitalization (276 hrs vs. 132 hrs, p < .0005) and had three times the odds for all-cause in-hospital mortality compared to patients without QT prolongation (odds ratio 2.99 95% confidence interval 1.1-8.1). CONCLUSIONS: We find QT prolongation to be common (24%), with Torsade de Pointes representing 6% of in-hospital cardiac arrests. Predictors of QT prolongation in the acutely ill population are similar to those previously identified in ambulatory populations. Acutely ill patients with QT prolongation have longer lengths of hospitalization and nearly three times the odds for mortality then those without QT prolongation.

How many patients need QT interval monitoring in critical care units? Preliminary report of the QT in Practice study.

UNLABELLED: Recent Scientific Statement from the American Heart Association (AHA) recommends that hospital patients should receive QT interval monitoring if certain conditions are present: QT-prolonging drug administration or admission for drug overdose, electrolyte disturbances (K, Mg), and bradycardia. No studies have quantified the proportion of critical care patients that meet the AHA's indications for QT interval monitoring. This is a prospective study of 1039 critical care patients to determine the proportion of patients that meet the AHA's indications for QT interval monitoring. Secondary aim is to evaluate the predictive value of the AHA's indications in identifying patients who actually develop QT interval prolongation. METHODS: Continuous QT interval monitoring software was installed in all monitored beds (n = 154) across 5 critical care units. This system uses outlier rejection and median filtering in all available leads to construct an root-mean-squared wave from which the QT measurement is made. Fridericia formula was used for heart rate correction. A QT interval greater than 500 milliseconds for 15 minutes or longer was considered prolonged for analyses. To minimize false positives all episodes of QT prolongation were manually over read. Clinical data was abstracted from the medical record. RESULTS: Overall 69% of patients had 1 or more AHA indications for QT interval monitoring. More women (74%) had indications than men (64%, P = .001). One quarter (24%) had QT interval prolongation (>500 ms for ≥15 minutes). The odds for QT interval prolongation increased with the number of AHA indications present; 1 indication, odds ratio (OR) = 3.2 (2.1-5.0); 2 indications, OR = 7.3(4.6-11.7); and 3 or more indications OR = 9.2(4.8-17.4). Positive predictive value of the AHA indications for QT interval prolongation was 31.2%; negative predictive value was 91.3%. CONCLUSION: Most critically ill patients (69%) have AHA indications for QT interval monitoring. One quarter of critically ill patients (24%) developed QT interval prolongation. The AHA indications for QT interval monitoring successfully captured the majority of critically ill patients developing QT interval prolongation.

Quasi-experimental study to improve nurses' QT-interval monitoring: results of QTIP study.

BACKGROUND: A collaboration led by the American Heart Association recently released the scientific statement "Prevention of Torsade de Pointes in Hospital Settings." Patients receiving proarrhythmic drugs, who have electrolyte disturbances, or who have bradyarrhythmias require QT-interval monitoring. Prior studies have demonstrated that physicians have a poor level of proficiency at calculating QT intervals. The ability of nurses at calculating QT intervals remains untested. OBJECTIVES: To evaluate nurses' knowledge and ability to perform QT/QTc interval monitoring. METHODS: At a single institution, 47 QT-education classes were provided to 480 eligible nurses who regularly perform cardiac monitoring. All nurses completed a researcher-developed knowledge test at baseline and after the QT-related education intervention. RESULTS: Overall 379 nurses participated (mean age 39 [SD, 10] years), 71% had more than 5 years' nursing experience. Total test scores increased after intervention (46% vs 77%, P < .001). Education significantly improved marking of the QT/RR intervals (QT: 65% vs 91%, RR: 83% vs 90%, P ≤ .001 and P = .02) and measurement of the QT/RR intervals (QT: 47% vs 84%, RR: 35% vs 71% P ≤ .001 and P ≤ .001). Calculation of the QTc interval also increased significantly (6% vs 52%, P ≤ .001). CONCLUSIONS: Our study results demonstrate that nurses' baseline ability to perform QT interval monitoring is extremely poor. An unacceptable amount of error persists after an educational intervention. Accurate computer-assisted methods are needed to reduce the error associated with manual QT-interval monitoring.

Implantable left ventricular assist devices.

The first bridge to transplant with a left ventricular assist device (LVAD) was preformed over 20 years ago. Since that time, the devices have continued to evolve and now patients are being supported with devices as an alternative to transplantation. The primary indication of end-stage heart failure remains the same but increased knowledge about patient selection, the timing of implant, and patient management have contributed to improved outcomes with decreasing adverse events. Multiorgan failure, right ventricular failure, bleeding, infection, thromboembolism, and device malfunction continue to be the most serious threats to long-term survival in these patients. Despite that, patients who do well are now able to be discharged from the hospital and resume relatively normal lives with the devices. The article reviews 3 of the most widely used LVADs for bridge to transplant therapy: the Thoratec; HeartMate vented electric; and the Novacor Left Ventricular Assist System. Indications, mechanism of operation, clinical problems, and out-of-hospital preparation are outlined.