Feasibility of a Novel Augmented 6-Minute Incremental Step Test: A Simplified Cardiorespiratory Fitness Assessment Tool [Duke University]

Researchers at Duke University present the feasibility of a novel bedside augmented 6MIST ‘utilizing multimodal, wearable technology as a simple, inexpensive, and potentially scalable alternative to current traditional form of CRF assessment in selected settings.” The key CPET metrics included peak VO2, VE, O2 pulse, and COP obtained during this 6MIST study strongly correlate with those obtained from iCPET.

To the best of their knowledge, Duke Researchers state this is the first study to describe the use of stationary 6MIST especially in conjunction with the CPET – capable wearables. “The 6-minute step test as equivalent to the standard 6MWT using a portable 20-cm-high step without a protocolized increment in the exercise intensity has been previously described and validated in (HF) heart failure population…Compared to other exercise protocols, we find the stationary 6MIST to be the most appealing protocol to be coupled with the wearable CPET equipment. The 6MIST, in contrast to the 6MWT, more closely simulates the standard CPA as the 6MIST entails a more physiologic ramp exercise protocol.”

The study was supported by the National, Heart Lung and Blood Institute (NHLBI), the American heart Association and Duke Chair’s Award.

Excerpts from the 6MIST below. For the full study, please click here.

“The proposed roles of augmented 6MIST would be to allow more frequent interval assessment of CRF in patients with HF or other cardiopulmonary conditions and to timely evaluate patients with worsening cardiopulmonary symptoms, and objectively quantify worsening functional capacity.’
As well, ‘these 6MIST- measured CPET parameters could be extremely useful to help clinicians understand relative changes or trends over more frequent intervals. These simple and less expensive tests could also be considered as screening tools in the clinic in stable patients that are doing well to avoid the inconvenience of in-lab CPET.”

“As the main goal of this pilot study was to demonstrate the feasibility in terms of safety and practicality of performing the 6MIST and incorporating two wearables as a new POC CRF, testing strategy, we did not intend to determine the accuracy or validity of the 6MIST derived, CPET or haemodynamic measurements.  Our primary aim was to assess the degree of consistency (ICC) rather than absolute agreement (BA plot).”

“Augmented 6MIST with simultaneous portable metabolic breath analyzer and signal morphology – based impedance cardiograph is a feasible, bedside test and could provide additional cardio-pulmonary exercise parameters and exercise CO as a promising alternative to a formal CPET for certain clinical scenarios. Strong correlation of cardiopulmonary exercise metrics including peak VO2 between two functional assessment strategies is demonstrated.”

For full details of the study methodology and results, please click here.

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