Use of the 6-min walk distance to identify variations in treatment benefits from implantable cardioverter-defibrillator and amiodarone: results from the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial)

J Am Coll Cardiol. 2014 Jun 17;63(23):2560-2568. doi: 10.1016/j.jacc.2014.02.602. Epub 2014 Apr 9.


Objectives: The purpose of this study was to determine if 6-min walk test data assists in treatment decisions for patients with heart failure.

Background: In the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial), a pre-specified subgroup analysis showed that patients with New York Heart Association functional class III symptoms did not benefit from implantable cardioverter-defibrillator (ICD) therapy and appeared to be harmed by amiodarone, whereas New York Heart Association functional class II patients obtained significant survival benefit from ICD. We postulated that a more objective measure of functional capacity, such as 6-min walk (6MW) distance, might provide a better tool for selecting these preventive therapies.

Methods: A 6MW test was performed before randomization in 2,397 patients. Median follow-up was 45.5 months. All-cause mortality was the primary endpoint, with cause-specific mortality (heart failure, arrhythmic) examined in secondary analyses.

Results: The hazard ratios (HRs) for ICD therapy compared to placebo were estimated within tertiles of baseline 6MW distance: HR: 0.42 (95% confidence interval [CI]: 0.26 to 0.66) for 6MW distance >386 m (top tertile); HR: 0.57 (95% CI: 0.39 to 0.83) for 6MW distance 288 to 386 m (middle tertile); and HR: 1.02 (95% CI: 0.75 to 1.39) for 6MW distance <288 m (bottom tertile). The corresponding HRs for amiodarone compared to placebo were 0.68 (95% CI: 0.46 to 1.02) for the top, 0.86 (95% CI: 0.61 to 1.21) for the middle, and 1.56 (95% CI: 1.17 to 2.09) for the bottom tertile. The 6MW distance was inversely related to heart failure-related mortality but not to arrhythmic mortality. ICD therapy reduced arrhythmic mortality in the top 2 tertiles of 6MW, but had no effect on heart failure mortality.

Conclusions: A baseline 6MW distance <288 m identified a subgroup of SCD-HeFT patients who were harmed by amiodarone therapy and did not benefit from ICD. (Sudden Cardiac Death in Heart Failure Trial [SCD-HeFT]; NCT00000609).

Keywords: 6-min walk; amiodarone; congestive heart failure; implantable cardioverter-defibrillator; sudden cardiac death.

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Amiodarone / administration & dosage
  • Amiodarone / therapeutic use*
  • Anti-Arrhythmia Agents / administration & dosage
  • Anti-Arrhythmia Agents / therapeutic use
  • Combined Modality Therapy
  • Death, Sudden, Cardiac / epidemiology
  • Death, Sudden, Cardiac / prevention & control*
  • Defibrillators, Implantable*
  • Exercise Test / methods*
  • Exercise Tolerance / physiology*
  • Female
  • Follow-Up Studies
  • Heart Failure / mortality
  • Heart Failure / physiopathology
  • Heart Failure / therapy*
  • Humans
  • Male
  • Middle Aged
  • Stroke Volume
  • Survival Rate / trends
  • Time Factors
  • Treatment Outcome
  • United States / epidemiology
  • Walking / physiology*


  • Anti-Arrhythmia Agents
  • Amiodarone

Associated data