QT dynamics early after exercise as a predictor of mortality

Nils P. Johnson, Thomas A. Holly, Jeffrey Goldberger

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Background: Exercise and QT dynamics during ambulatory monitoring impact mortality in a variety of populations. Heart rate recovery (HRR) after exercise is a known strong predictor of mortality. Objective: This study assessed the independent prognostic significance of the QT response to changing heart rate (QT dynamics) during recovery from exercise. Methods: The cohort included patients referred for treadmill exercise stress testing over a 5-year period. Patients had to have at least 4 electrocardiographic tracings within 5 minutes of peak exercise. One had to be recorded 60 seconds into recovery to calculate the HRR. Linear regression of the QT-RR relation during recovery was used to predict the QT interval at cycle lengths of 500 and 600 ms (QT-500 and QT-600). Only studies with an R2 < 0.9 (72%) were retained. Optimal binary cut points were chosen. All-cause mortality was determined from either the Social Security Death Index or hospital records. Results: A total of 2,994 patients met inclusion criteria; 228 (7.6%) died during an average follow-up of 7.6 ± 1.9 years. Abnormal QT-500 (>316 ms) was the strongest univariate QT dynamics predictor in a Cox proportional hazards model (hazard ratio = 2.13, P <.001). It remained an independent predictor of mortality after adjustment for age, exercise capacity, medications, single photon emission computed tomography defects, and abnormal (<12 beats/min) HRR (hazard ratio = 1.46, P = .014). Conclusion: An abnormal predicted QT interval at 500 ms (120 beats/min) during recovery from exercise independently predicts all-cause mortality. Because QT dynamics in recovery incorporate information on both repolarization and autonomic responsiveness, its role in risk prediction for sudden cardiac death should be further explored.

Original languageEnglish (US)
Pages (from-to)1077-1084
Number of pages8
JournalHeart Rhythm
Volume7
Issue number8
DOIs
StatePublished - Sep 24 2010
Externally publishedYes

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Exercise
Mortality
Heart Rate
Ambulatory Monitoring
Sudden Cardiac Death
Single-Photon Emission-Computed Tomography
Proportional Hazards Models
Linear Models
Population

Keywords

  • Exercise stress test
  • Heart rate recovery
  • Mortality
  • Prognosis
  • QT dynamics

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

QT dynamics early after exercise as a predictor of mortality. / Johnson, Nils P.; Holly, Thomas A.; Goldberger, Jeffrey.

In: Heart Rhythm, Vol. 7, No. 8, 24.09.2010, p. 1077-1084.

Research output: Contribution to journalArticle

Johnson, Nils P. ; Holly, Thomas A. ; Goldberger, Jeffrey. / QT dynamics early after exercise as a predictor of mortality. In: Heart Rhythm. 2010 ; Vol. 7, No. 8. pp. 1077-1084.
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