JACC: Advances (Aug 2024)

Feasibility of a Novel Augmented 6-Minute Incremental Step Test

  • Jeroen Molinger, MS,
  • Veraprapas Kittipibul, MD,
  • J. Matthew Gray, MS,
  • Vishal N. Rao, MD, MPH,
  • Stratton Barth, BS,
  • Ashley Swavely, MS,
  • Brian Coyne, MEd,
  • Aubrie Coburn, MS,
  • Jan Bakker, MD,
  • Paul E. Wischmeyer, MD,
  • Cynthia L. Green, PhD,
  • David MacLeod, MD,
  • Manesh Patel, MD,
  • Marat Fudim, MD, MHS

Journal volume & issue
Vol. 3, no. 8
p. 101079

Abstract

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Background: The cardiopulmonary exercise test (CPET) is considered a gold standard in assessing cardiorespiratory fitness (CRF) but has limited accessibility due to competency requirements and cost. Incorporating portable sensor devices into a simple bedside test of CRF could improve diagnostic and prognostic value. Objectives: The authors sought to evaluate the association of an augmented 6-minute incremental step test (6MIST) with standard CPET. Methods: We enrolled patients undergoing clinically indicated supine cycle ergometry CPET with invasive hemodynamics (iCPET) for the same-day 6MIST. CRF-related variables were simultaneously recorded using a signal morphology-based impedance cardiograph (PhysioFlow Enduro) and a portable metabolic analyzer (VO2 Master Pro) during incremental pace stationary stepping. The correlation between CPET and hemodynamic parameters from both tests was assessed using the intraclass correlation coefficient (ICC). Results: Fifteen patients (mean age 60 ± 14 years, 40% female, 27% Black) were included. All patients who agreed to undergo 6MIST completed the study without any test-related adverse events. We observed good to excellent correlation between iCPET- and 6MIST-measured CPET parameters: peak heart rate (ICC = 0.60; 95% CI: 0.15-0.85), absolute peak O2 consumption (VO2) (ICC = 0.77; 95% CI: 0.44-0.92), relative peak VO2 (ICC = 0.64; 95% CI: 0.20-0.86), maximum ventilation (ICC = 0.59; 95% CI: 0.13-0.84), O2 pulse (ICC = 0.71; 95% CI: 0.33-0.89), and cardiorespiratory optimal point (ICC = 0.82; 95% CI: 0.52-0.94). No significant correlation was determined between iCPET and 6MIST in measuring cardiac index at rest (ICC = 0.19; 95% CI: −0.34 to 0.63) or at peak exercise (ICC = 0.36; 95% CI: −0.17 to 0.73). Conclusions: We demonstrate the feasibility of a novel augmented 6MIST with wearable devices for simultaneous CPET and hemodynamic assessment. 6MIST-measured CPET parameters were strongly correlated with the iCPET-derived measurements. Additional studies are needed to confirm the validity of the 6MIST compared to standard upright CPET.

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