Electrocardiographic measures of repolarization heterogeneity are not predictive for Torsades de Pointes among undifferentiated patients with prolonged QTc: A case control study.

INTRODUCTION: Torsades de Pointes (TdP) is a potentially lethal polymorphic ventricular tachydysrhythmia associated with and caused by prolonged myocardial repolarization. However, prediction of TdP is challenging. We sought to determine if electrocardiographic myocardial repolarization heterogeneity is necessary and predictive of TdP. METHODS: We performed a case control study of TdP at a large urban hospital. We identified cases based on a hospital center electrocardiogram (ECG) database search for tracings from 1/2005 to 6/2019 with heart rate corrected QT (QTc) > 500, QRS < 120, and heart rate (HR) < 60, and a subsequent natural language search of electronic health records for the terms: TdP, polymorphic ventricular tachycardia, sudden cardiac death, and relevant variants. Controls were drawn in a 2:1 ratio to cases from a similar pool of ECGs, and matching for QTc, heart rate, sex, and age. We abstracted historical, laboratory, and ECG data using detailed written instructions and an electronic database. We included a second blinded data abstractor to test data abstraction and manual ECG measurement reliability. We used General Electric (GE) QT Guard software for automated repolarization measurements. We compared groups using unpaired statistics. RESULTS: We included 75 cases and 150 controls. The number of current QTc prolonging medications and serum electrolytes were substantially the same between the two groups. We found no significant difference in measures of QT or T wave repolarization heterogeneity. CONCLUSION: Electrocardiographic repolarization heterogeneity is not greater in otherwise unselected patients with QTc prolongation who suffer TdP and does not appear predictive of TdP. However, previous observations suggest specific repolarization characteristics may be useful for defined patient subgroups at risk for TdP.

Overcoming barriers to developing seamless ST-segment elevation myocardial infarction care systems in the United States: recommendations from a comprehensive Prehospital 12-lead Electrocardiogram Working Group.

BACKGROUND: Reducing time to reperfusion treatment for patients with ST-segment elevation myocardial infarction (STEMI) improves patient outcomes. Few medical systems consistently meet current benchmarks regarding timely access to treatment. Studies have widely demonstrated that prehospital 12-lead electrocardiography can facilitate early catheterization laboratory activation and is the most effective means of decreasing patients' time to treatment. METHODS: We gathered experts to examine the barriers to implementation of prehospital 12-lead electrocardiographic monitoring and transmission to in-hospital cardiologists in creating seamless STEMI care systems (STEMI-CS) and propose multidisciplinary approaches to overcoming these barriers. RESULTS AND CONCLUSIONS: Physicians, hospital systems, and emergency medical services often lack coordination of care delivery and receive fragmented funding and oversight. Clinical and regulatory guidelines do not emphasize local solutions to achieving clinical benchmarks, do not target incentives at all components of the STEMI-CS, and underemphasize risk-based approaches to protecting patient health. Integration of the multiple complex components involved in STEMI-CS is essential to improving care delivery.

The effects of noise on computerized electrocardiogram measurements.

UNLABELLED: Computerized measurements provide objective and reproducible assessments of the electrocardiogram (ECG). These measurements may be affected by noise or other lead quality issues. The effects of noise on the repeatability of computer-measured PR interval, QRS duration, QT interval, P/QRS/T axes, and ST levels were examined. METHODS: The 125 ECGs of the Common Standards for Quantitative Electrocardiography (CSE) measurement database (MO1 series) were merged with records from the MIT Noise Stress Test database. For each CSE ECG, 720 unique noise ECGs were created, for a total of 90,000 noisy ECGs. Computerized measurements from the noisy ECGs were compared to the original ECG measurements. The repeatability of the measurements was assessed as a function of a lead quality score. RESULTS: The repeatability of the measurements was found to be in excellent agreement with the original ECG measurements when the noise level was no worse than that of the original ECGs. Noise did not introduce any bias to the measurements, although not surprisingly, the variation of the errors increased as the lead quality degraded.