Exercise cardiovascular magnetic resonance imaging allows differentiation of low-risk pulmonary arterial hypertension

https://doi.org/10.1016/j.healun.2019.01.1305Get rights and content

BACKGROUND

Patients with pulmonary arterial hypertension (PAH) have a decreased ability to compensate for demands on increased cardiac output, such as during exercise. In this study we aimed to differentiate cardiac exercise responses in patients with PAH, stratified according to known measurements of disease severity.

METHODS

Right and left ventricular end-diastolic volume and end-systolic volume, stroke volume (SV), and cardiac output were measured in 20 patients with PAH and a lower risk of mortality with 6-month intervals using cardiovascular magnetic resonance (CMR) imaging during rest and during ergometer exercise (totaling 44 scans). Exercise measurements were compared with resting cardiac conditions and clinical assessment using mixed model statistics.

RESULTS

SV response during exercise was associated with disease severity. World Health Organization functional class (WHO FC) I and right ventricular end-diastolic volume (RVEDV) <221 ml were associated with increased SV during exercise (WHO FC I: 7% increase in SV; p < 0.001). In contrast, WHO FC II was associated with an 8% decrease in SV (p = 0.02), and SV response declined progressively with right ventricular dilation (7-ml decrease in SV per 100-ml increase in RVEDV; p < 0.001).

CONCLUSIONS

Assessment of right ventricular function with CMR during exercise stratifies patients currently perceived as having a low risk of mortality into different degrees of right ventricular inotropic reserve. Reduced SV during exercise is a plausible factor to increased risk of decompensation, possibly warranting targeted therapy intensification to restore right ventricular functional reserve.

Section snippets

Patient inclusion

Patients were eligible for inclusion if they had previously been diagnosed with PAH according to recent guidelines.19, 20 Renewed right heart catheterization (RHC) was not performed in this study, as it is only performed for confirmation of the diagnosis and if patients are clinically deteriorating. Inclusion criteria were age ≥18 years and cardiac sinus rhythm. Exclusion criteria were presence of magnetic implants unsuited for CMR (CMR-compatible implanted infusion pumps were allowed), PAH

Patient inclusion and characteristics

During 2016 and 2017, 24 patients were asked to participate in our study. A total of 4 patients declined participation due to very low perceived functional capacity. The remaining 20 patients were scanned every 6 months for a total of 4 times (1 patient), 3 times (8 patients), and 2 times (5 patients), or only once (6 patients), totaling 44 scans over 2 years. Thus, 14 patients received at least 1 follow-up scan. The sex distribution was typical for modern PAH demographics, with 13 women and 7

Discussion

In this study, patients with PAH receiving specific treatment and with a predominantly low-risk profile were found to have a stratified response to exercise and may be divided into patients with increasing SV during exercise and patients with decreasing SV. Decreasing SV during exercise is associated with larger resting RV volumes and WHO FC II. Thus, the larger RV fails during exercise, as it progressively dilates with a concurrent decrease in SV. The dilated RV has exhausted its potential to

Limitations

The present study was designed to assess exercise response in patients with low-risk PAH. RHC was not renewed in relation to exercise CMR measurements. Inclusion of renewed RHC could have provided insight into the exercise response according to current hemodynamic status. Assessing exercise response at a perceived effort of >13 out of 20 on the Borg RPE scale was motivated by the concept of using a simple, individually reproducible method, expected to affect stroke volume. Exercise testing

Disclosure statement

The authors have no conflicts of interest to disclose.

This work was supported by an unrestricted grant from Actelion Nordic.

The authors thank the invasive cardiologists at the Department of Cardiology for performing right heart catheterizations to establish the PAH diagnosis. Section of Biostatistics, University of Copenhagen, provided valuable help with statistical models for repeated measurements. We also thank Karin Jensen for overseeing the walking tests.

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