Abstract
Background
Cardiac magnetic resonance imaging in conjunction with exercise (exMR) and cardiopulmonary testing (CPET) to evaluate cardiopulmonary function has the potential of uncovering poorly understood mechanisms of dyspnea in patients that cannot be otherwise discerned with a single imaging modality.
Purpose
We prospectively evaluated the value of this technique in dyspneic patients with HIV without obvious cardiopulmonary etiologies to comprehensively assess mechanisms of dyspnea.
Methods
Thirty-six HIV patients with dyspnea without obvious cardiopulmonary causes [normal chest x-ray, normal resting LVEF and resting pulmonary artery (PA) pressures <40 mm Hg on echo] and exercise limitation [Modified Medical Research Council (MMRC) dyspnea scale >2] underwent testing using a novel combined exMR/CPET platform (Figure 1). Resting and exercise magnetic resonance imaging (MRI), including flow velocities across the pulmonary artery together with CPET was evaluated at pre and post peak stress. We analyzed the correlation between CPET and MRI pre and peak exercise variables.
Results
The mean age was 51 years; 60% were male; and mean absolute CD4 count was 718. Ventilator efficiency at peak exercise (Peak VO2) did not correlate with exMR parameters. Peak VE/VCO2 was negatively associated with peak LV and RV stroke volume (p values 0.002 & 0.005 respectively). There was a positive relationship between peak petCO2and LV cardiac output (p=0.02), peak exercise RV stroke volume (p=0.003), peak exercise LV stroke volume (p=0.02). Absolute CD4 count was positively correlated with post exercise pulmonary artery velocity (p=0.045). We found no correlation between absolute CD8 count and CMR and CPET exercise parameters.
Figure 1. MRI-CPET setting
Conclusion
HIV patients appear to have an impairment of ventilatory efficiency, exemplified by the association of VE/VCO2and PetCO2 with exMR parameters in the context of normal RV/LV contractile reserve and no evidence of Pulmonary arterial hypertension. A combined CPET/exMRI platform may provide new insight into cardiopulmonary function and the factors influencing exercise tolerance in symptomatic HIV patients.
Acknowledgement/Funding
7R01HL125060-03
PULMONARY ARTERY TUMOR MISTAKEN AS PULMONARY THROMBUS: MULTIPARAMETRIC CARDIAC MAGNETIC RESONANCE IMAGING
