Michael Leonard Scharf and Sidharth Bagga
Purpose: The 6 minute walk test used to evaluate patients with PH has many limitations. The ISWT, an automated progressively incremental and more physically demanding exercise test, has been useful to assess exercise tolerance in patients with severe COPD. Its application in patients with PH and particularly, pulmonary arterial hypertension (PAH) raises the concern of eliciting cardiovascular complications during testing. We wished to evaluate the safety of ISWT in patients with PH.
Methods: A retrospective review was performed on patients with RHC-confirmed PH who had undergone outpatient ISWT, predominantly those with WHO FC II and III. Eighty-four ISWTs from 46 patients were assessed according to WHO functional class (FC), echocardiogram, 6 distances walked, pulse oximetry, fatigue, BORG dyspnea scores, blood pressure, heart rate and adverse events.
Results: A total of 21 adverse events were reported from the 84 ISWT performed as follows: Two patients - angina, 1 - worsening dyspnea, 12 - locomotor difficulties including leg and joint pain, and 6 - lightheadedness. There were no deaths or sustained adverse events after the ISWT. There were no documented episodes of syncope or tachyarrhythmia’s even in patients with right ventricular dysfunction.
Conclusions: Performance of ISWT appears to be safe in stable outpatients with PH and right-sided heart disease as an assessment of the functional capacity in the PH population and should be included in future clinical trials to assess whether it may provide a meaningful assessment of patient exercise tolerance. Its limitations are similar to those shared by the 6 minute walk and include locomotor difficulties.
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