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Torsade de Pointes: A Nested Case Control Study in an Integrated Health Care Delivery System
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  • Neha Mantri,
  • Meng Lu,
  • Jonathan Zaroff,
  • Neil Risch,
  • Thomas Hoffmann,
  • Akinyemi Oni-Orisan,
  • Catherine Lee,
  • Carlos Iribarren
Neha Mantri
Kaiser Permanente San Francisco Medical Center
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Meng Lu
Kaiser Permanente Division of Research
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Jonathan Zaroff
Kaiser San Francisco Medical Center
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Neil Risch
University of California San Francisco
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Thomas Hoffmann
University of California, San Francisco
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Akinyemi Oni-Orisan
University of California San Francisco
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Catherine Lee
Kaiser Permanente Division of Research
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Carlos Iribarren
Kaiser Permanente Division of Research

Corresponding Author:[email protected]

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Abstract

Background. TdP is a form of polymorphic ventricular tachycardia which develops in the setting of a prolonged QT interval. There is limited data describing risk factors, treatment and outcomes of this potentially fatal arrhythmia. Objective: Our goals were: 1) to validate cases presenting with Torsade de Pointes (TdP); 2) to identify modifiable risk factors; and 3) to describe the management strategies used for TdP and its prognosis in a real-world health care setting. Methods. Case-control study (with 2:1 matching on age, sex and race/ethnicity) nested within the Genetic Epidemiology Research on Aging (GERA) cohort. Follow-up of the cohort for case ascertainment was between 01/01/2005 and 12/31/2018. Results. A total of 56 cases of TdP were confirmed (incidence rate= 3.6 per 100,000 persons/years). The average (SD) age of the TdP cases was 74 (13) years, 55 percent were female and 16 percent non-white. The independent predictors of TdP were potassium concentration < 3.6 mEq/L (OR=10.6), prior history of atrial fibrillation/flutter (OR=6.2), QTc > 480 ms (OR=4.4) and prior history of coronary artery disease (OR=2.6). Exposure to furosemide and amiodarone were significantly greater in cases than in controls. The most common treatment for TdP was IV magnesium (78.6%) and IV potassium repletion (73.2%). The in-hospital and 1-year mortality rates for TdP cases were 10.7% and 25.0% percent, respectively. Conclusions. These findings may inform quantitative multivariate risk indices for the prediction of TdP and could guide practitioners on which patients may qualify for continuous ECG monitoring and/or electrolyte replacement therapy.