Incremental shuttle walk test distance and autonomic dysfunction predict survival in pulmonary arterial hypertension

https://doi.org/10.1016/j.healun.2017.04.008Get rights and content

Background

To ensure effective monitoring of pulmonary arterial hypertension (PAH), a simple, reliable assessment of exercise capacity applicable over a range of disease severity is needed. The aim of this study was to assess the ability of the incremental shuttle walk test (ISWT) to correlate with disease severity, measure sensitivity to change, and predict survival in PAH.

Methods

We enrolled 418 treatment-naïve patients with PAH with baseline ISWT within 3 months of cardiac catheterization. Clinical validity and prognostic value of ISWT distance were assessed at baseline and 1 year.

Results

ISWT distance was found to correlate at baseline with World Health Organization functional class, Borg score, and hemodynamics without a ceiling effect (all p < 0.001). Walking distance at baseline and after treatment predicted survival; the area under the receiver operating characteristic curve for ability of ISWT distance to predict mortality was 0.655 (95% confidence interval 0.553–0.757; p = 0.004) at baseline and 0.737 (95% confidence interval 0.643–0.827; p < 0.001) at 1 year after initiation of treatment. Change in ISWT distance also predicted survival (p = 0.04). Heart rate (HR) and systolic blood pressure (SBP) parameters reflecting autonomic response to exercise (highest HR, change in HR, HR recovery at 1 minute >18 beats/min, highest SBP, change in SBP, and 3-minute SBP ratio) were significant predictors of survival (all p < 0.05).

Conclusions

In patients with PAH, the ISWT is simple to perform, allows assessment of maximal exercise capacity, is sensitive to treatment effect, predicts outcome, and has no ceiling effect. Also, measures of autonomic function made post-exercise predict survival in PAH.

Section snippets

Methods

Data were retrieved from the ASPIRE (Assessing the Spectrum of Pulmonary hypertension Identified at a REferral centre) registry for consecutive patients with a diagnosis of pulmonary hypertension between 2001 and 2010.24 The diagnostic evaluation and clinical classification of these patients have been described previously.24 For inclusion, patients were required to have PAH and a baseline ISWT within 3 months of cardiac catheterization and before the introduction of targeted PAH therapy.

Results

Between 2001 and 2010, 418 patients had a diagnosis of PAH and a baseline ISWT within 3 months of cardiac catheterization and before the introduction of targeted therapy. Baseline characteristics are presented in Table 1. There were high levels of data completeness for all parameters studied (>90%). Median distance walked at baseline was 150 m, and median time to complete the walk was 3.67 minutes. The ISWT was found to be a safe test with no major adverse event (death, need for cardiopulmonary

Discussion

We have demonstrated in patients with PAH that distance walked using the ISWT correlates with pulmonary hemodynamics, World Health Organization functional class, and resting Borg score and predicts prognosis both at baseline and at subsequent follow-up, all without a ceiling effect. Furthermore, we have shown that measures of autonomic function made immediately after exercise predict survival in PAH. These attributes of the ISWT make it an attractive field walking test in patients with PAH.

At

Disclosure statement

None of the authors has a financial relationship with a commercial entity that has an interest in the subject of the presented manuscript or other conflicts of interest to disclose.

The following financial relationships to commercial entities are not related to the presented manuscript. In the past 3 years, A.C., C.A.E., D.G.K., N.H., and R.C. have received honoraria for participation in advisory boards and for giving lectures, personal fees to attend educational meetings, and non-financial

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