Association of PET-measured myocardial flow reserve with echocardiography-estimated pulmonary artery systolic pressure in patients with hypertrophic cardiomyopathy.

Min Zhao,Jeffrey P Leal,Dean F Wong,Min Liu,Yun Zhou,Martin G Pomper,Benjamin M W Tsui

doi:10.1371/journal.pone.0212573

Abstract

BackgroundPulmonary hypertension (PH) is a known complication of HCM and is a strong predictor of mortality. We aim to investigate the relationship between microvascular dysfunction measured by quantitative PET and PH in HCM patients.MethodsEighty-nine symptomatic HCM patients were included in the study. Each patient underwent two 20-min 13N-NH3 dynamic PET scans for rest and stress conditions, respectively. A 2-tissue irreversible compartmental model was used to fit the segments time activity curves for estimating segmental and global myocardial blood flow (MBF) and myocardial flow reserve (MFR). Echocardiographic derived PASP was utilized to estimate PH.ResultsPatients were categorized into two groups across PASP: PH (PASP > 36 mmHg) and no-PH (PASP ≤ 36 mmHg). patients with PH had larger left atrium, ratio of higher inflow early diastole (E) and atrial contraction (A) waves, E/A, and ratio of inflow and peak early diastolic waves, E/e', significantly reduced global stress MBF (1.85 ± 0.52 vs. 2.13 ± 0.56 ml/min/g; p = 0.024) and MFR (2.21 ± 0.57 vs. 2.62 ± 0.75; p = 0.005), while the MBFs at rest between the two groups were similar. There were significant negative correlations between global stress MBF/MFR and PASP (stress MBF: r = -0.23, p = 0.03; MFR: r = -0.32, p = 0.002); for regional MBF and MFR measurements, the highest linear correlation coefficients were observed in the septal wall (stress MBF: r = -0.27, p = 0.01; MFR: r = -0.31, p = 0.003). Global MFR was identified to be independent predictor for PH in multivariate regression analysis.ConclusionEchocardiography-derived PASP is negatively correlated with global MFR measured by 13N-NH3 dynamic PET. Global MFR is suggested to be an index of PH in HCM patients.

Highlights

Hypertrophic cardiomyopathy (HCM) is the most common heritable cardiomyopathy, characterized by cardiac hypertrophy and phenotypic heterogeneity [1, 2]
Patients were categorized into two groups across pulmonary artery systolic pressures (PASP): pulmonary hypertension (PH) (PASP > 36 mmHg) and noPH (PASP 36 mmHg). patients with PH had larger left atrium, ratio of higher inflow early diastole (E) and atrial contraction (A) waves, E/A, and ratio of inflow and peak early diastolic waves, E/e’, significantly reduced global stress myocardial blood flow (MBF) (1.85 ± 0.52 vs. 2.13 ± 0.56 ml/min/g; p = 0.024) and myocardial flow reserve (MFR) (2.21 ± 0.57 vs. 2.62 ± 0.75; p = 0.005), while the MBFs at rest between the two groups were similar
Echocardiography-derived PASP is negatively correlated with global MFR measured by 13N-NH3 dynamic positron emission tomography (PET)

Summary

Introduction

Hypertrophic cardiomyopathy (HCM) is the most common heritable cardiomyopathy, characterized by cardiac hypertrophy and phenotypic heterogeneity [1, 2]. Growing evidence suggests that the assessment of microvascular function detected by quantitative positron emission tomography (PET) could play an important role in the evaluation and management of myocardial ischemia in patients with HCM [7]. Impaired hyperemic myocardial blood flow (MBF) and myocardial flow reserve (MFR) were regarded as equivalent to the microvascular dysfunction [8]. To date, it remains unknown whether microvascular function and PH are associated. We used 13N-NH3 dynamic PET imaging to explore the possible quantitative relationship between MBF/MFR and pulmonary artery systolic pressures (PASP) measured by Doppler echocardiography. We aim to investigate the relationship between microvascular dysfunction measured by quantitative PET and PH in HCM patients

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Conclusion