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Beat-to-beat corrected QT analysis detects corrected QT prolongation in 50 consecutive telemetry-monitored patients
Judy E Davidson1, Donna Agan, Dan L Ballard
1Judy E. Davidson, DNP, RN, FCCM Director, Research Integration and Management, Scripps Clinical Research Center, La Jolla, California. Donna Agan, EdD Director of Operations Integration, Scripps Mercy Hospital, San Diego, California. Dan L. Ballard Jr, BS Process Validation Engineer, Welch Allyn Monitoring, Beaverton, Oregon. Huu Tam D. Truong, MD Cardiology Fellow, Cardiology Department, University of Arizona, Sarver Heart Center, Tucson. Christine M. Bridgen, PharmD Clinical Pharmacist, Department of Pharmacy, Scripps Encinitas Hospital, San Diego, California. Steven Rubino Network + Clinical Systems Specialist, Lead, Biomedical Engineering Department, Scripps Mercy Hospital, San Diego, California. Harminder Sikand, PharmD Clinical Director, Department of Pharmacy, Scripps Mercy Hospital, San Diego, California. Joseph Stein, MD, FACC Electrophysiologist, Division of Cardiology/Electrophysiology, Scripps Mercy Hospital, San Diego, California.
Insights
Continuous monitoring detected corrected QT (QTc) prolongation in all 50 hospitalized patients, a rate significantly higher than standard methods. Hospital medications were a common cause of QTc prolongation.
Area of Science:
- Cardiology
- Clinical Electrophysiology
Background:
- Current guidelines recommend monitoring for corrected QT (QTc) prolongation.
- The incidence of QTc prolongation is not well-established.
- Episodic measurements may fail to identify at-risk individuals.
Purpose of the Study:
- To determine the incidence of QTc prolongation in hospitalized telemetry patients.
- To evaluate the effectiveness of beat-to-beat monitoring for QTc prolongation detection.
Main Methods:
- Consecutive analysis of telemetry waveforms from hospitalized patients.
- Identification of 50 patients with QTc prolongation (men >470 ms, women >480 ms).
- Confirmation of QTc prolongation by manual calculation; exploration of risk factors and outcomes.
Main Results:
- 100% of 50 analyzed patients exhibited QTc prolongation episodes via beat-to-beat monitoring.
- Hospital medications contributed to QTc prolongation in 62% of patients.
- Standard care (manual analysis or 12-lead ECG) detected only 28% of QTc prolongation cases.
Conclusions:
- Beat-to-beat monitoring significantly increases the detection rate of QTc prolongation compared to standard methods.
- Hospital-administered medications are a frequent contributor to QTc prolongation.
- Improved definitions are needed to assess proarrhythmic risk with advancing automated detection technology.
Background:
The American Heart Association/American College of Cardiology Foundation recommends monitoring for corrected QT (QTc) prolongation. The incidence of QTc prolongation in the general public is unknown. Episodic measurements may miss patients at risk.
Objective:
The purpose of this study was to determine the incidence of QTc prolongation in hospitalized telemetry patients when beat-to-beat monitoring, confirmed by manual calculation, was used for detection.
Methods:
After institutional review board approval was obtained, waveforms of telemetry-monitored patients were analyzed consecutively until 50 patients with prolonged QTc were identified (QTc >470 milliseconds in men and >480 milliseconds in women). Prolongation was confirmed by manual calculation. Incidence was calculated. Clinical risk factors and the outcomes of torsades de pointe or sudden death were explored.
Results:
Telemetry waveforms were evaluated for 192 444 minutes (3207.4 hours) of recordings, yielding 8,076,653 QTc measurements. In 50 consecutive patients (24 [48%] men), 100% had verified episode(s) of QTc prolongation. Home medications that could result in QTc prolongation were identified in 9 patients (18%). Hospital medications with risk of QTc prolongation were administered to 31 patients (62%). Sixteen patients (32%) were not on a QTc-prolonging medication. Corrected QT prolongation risk factors in the history were found in 2 patients (4%) and hypomagnesemia or hypokalemia was seen in 6 patients (12%). Twelve-lead electrocardiogram detected prolonged QTc in 13 of 45 patients (26%). Prolongation of QTc was detected by standard of care manual analysis in 4 patients (8%). No patient experienced torsades de pointe or sudden death.
Conclusion:
With beat-to-beat analysis, QTc prolongation was detected in 100% of 50 consecutive patients where standard of care (nursing manual analysis or 12-lead electrocardiogram) would have detected 28%. Hospital medications were more likely to contribute to QTc prolongation than home medications.
Implications For Practice:
More specific definitions for determining proarrhythmic risk are needed as automated technology improves the capture rate of QTc prolongation events.
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