Semiquantitative myocardial perfusion reserve index (MPRI) assessment may shed light on ambiguous symptoms in severe aortic stenosis (AS) patients with angina but without coronary artery disease (CAD), according to findings published in the Journal of the American College of Cardiology.
Although angina is a common symptom for patients with severe AS without CAD, little is known about the pathogenesis of exertional angina. Therefore, researchers sought to determine whether microvascular dysfunction is responsible for chest pain in this population using adenosine-stress cardiac magnetic resonance (CMR) imaging.
“The assessment of the MPR through adenosine-stress CMR can confirm the presence of angina and may predict the imminent onset of angina in patients with severe AS without obstructive CAD,” the authors wrote. “Thus, MPRI shows promise as a potential clarifier of symptoms in patients with severe AS who had ambiguous symptoms.”
A total of 117 patients with severe AS without obstructive CAD were enrolled in the study between June 2012 and April 2015. An additional 20 participants were enrolled in the normal control group. Researchers divided the participants based on presence of exertional chest pain. They assigned them to either the angina group (n=43) or the asymptomatic group (n=41), and then calculated the semiquantitative MPRI for each group.
The average MPRI values were 0.90 ± 0.31 in severe AS patients, which were significantly lower compared with patients in the control group (1.25 ± 0.21; P<.001). These values were also much lower among patients with angina compared with patients in the asymptomatic group (0.74 ± 0.25 vs 1.08 ± 0.28; P<.001).
MPRI was the only independent predictor for angina (odds ratio: 0.003; P<.001). Additional univariate associations with MPRI were identified for diastolic blood pressure, E/eʹ ratio, LV volume and ejection fraction, cardiac index, presence of late gadolinium enhancement, and LV mass index, which was the strongest contributing factor to MPRI (standardization coefficient: -0.428; P<.001).
“As this study did not evaluate reversibility of the MPRI after AVR [aortic valve replacement] and prognosis of asymptomatic patient with decrease MPRI, additional research is needed to understand the reversibility of coronary microvascular dysfunction and prognostic value of MPRI as a biomarker,” the authors noted.
Ahn JH, Kim SM, Park SJ, et al. Coronary microvascular dysfunction as a mechanism of angina in severe as: prospective Adenosine-stress CMR study. J Am Coll Cardiol. 2016; 67(12):1412-1422. doi: 10.1016/j.jacc.2016.01.013.