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PET Subendocardial Perfusion in Patients With Hypertension
Quick Takes
- Lower subendocardial myocardial flow reserve (MFRsubendo) is associated with increased CV risk factors including diabetes and renal dysfunction, as well as with markers of myocardial injury and adverse LV structural parameters, independent of CV risk factors.
- Furthermore, lower MFRsubendo was associated with worse prognosis, including increased rates of all-cause death and HF hospitalization.
- These data suggest that PET quantification of subendocardial perfusion and MFR captures a relevant marker of pathophysiology and CV risk.
Study Questions:
What is the relationship of subendocardial perfusion with cardiac injury, structure, and a composite of major adverse cardiovascular and cerebral events (MACCE) consisting of death, heart failure (HF) hospitalization, myocardial infarction, and stroke?
Methods:
The investigators assessed layer-specific blood flow and myocardial flow reserve (MFR; stress/rest myocardial blood flow) by 13N-ammonia perfusion positron emission tomography (PET) in consecutive patients with hypertension without flow-limiting coronary artery disease (summed stress score <3) imaged at Brigham and Women's Hospital (Boston, MA) from 2015 to 2021. In this post hoc observational study, biomarkers, echocardiographic parameters, and longitudinal clinical outcomes were compared by tertiles of subendocardial MFR (MFRsubendo). Univariable- and multivariable-adjusted associations between MFRsubendo and elevated markers of myocardial injury, above the upper reference limit, were evaluated by logistic regression models.
Results:
Among 358 patients, the mean age was 70.6 ± 12.0 years, and 53.4% were male. The median MFRsubendo was 2.57 (interquartile range, 2.08-3.10), and lower MFRsubendo was associated with older age, diabetes, lower renal function, greater coronary calcium burden, and higher systolic blood pressure (p < 0.05 for all). In cross-sectional multivariable regression analyses, the lowest tertile of MFRsubendo was associated with myocardial injury and with greater left ventricular (LV) wall thickness and volumes compared with the highest tertile. Relative to the highest tertile, low MFRsubendo was independently associated with an increased rate of MACCE (adjusted hazard ratio [aHR], 2.99; 95% confidence interval [CI], 1.39-6.44; p = 0.005) and heart failure hospitalization (aHR, 2.76; 95% CI, 1.04-7.32; p = 0.042) over 1.1 (interquartile range, 0.6-2.8) years of median follow-up.
Conclusions:
The authors report that among patients with hypertension without flow-limiting coronary artery disease, impaired MFRsubendo was associated with CV risk factors, elevated cardiac biomarkers, cardiac structure, and clinical events.
Perspective:
This study reports that lower MFRsubendo is associated with increased CV risk factors including diabetes and renal dysfunction, as well as with markers of myocardial injury and adverse LV structural parameters, independent of CV risk factors and atherosclerotic burden. Furthermore, lower MFRsubendo was associated with worse prognosis, including increased rates of all-cause death and HF hospitalization. These data suggest that PET quantification of subendocardial perfusion and MFR captures a relevant marker of pathophysiology and CV risk. Additional studies linking subendocardial perfusion to comprehensive diastolic function assessment would be useful in further proving the hypothesized relationship between subendocardial ischemia, fibrosis, and HF among patients with hypertension.
Clinical Topics: Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Acute Heart Failure, Computed Tomography, Nuclear Imaging, Hypertension
Keywords: Heart Failure, Hypertension, Myocardial Perfusion Imaging, Positron-Emission Tomography
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