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Relationship of Subendocardial Perfusion to Myocardial Injury, Cardiac Structure, and Clinical Outcomes Among
Xiaolei Xu1,2,3, Sanjay Divakaran2,4, Brittany N Weber2,4
1Zhejiang University School of Medicine, Hangzhou, China (X.X., L.Z.).
Insights
Impaired subendocardial perfusion in hypertensive patients without coronary artery disease is linked to cardiac injury and higher risks of major adverse events. This highlights the importance of assessing myocardial flow reserve for cardiovascular risk stratification.
Area of Science:
- Cardiology
- Cardiovascular Imaging
- Hypertension Research
Background:
- Coronary microvascular dysfunction contributes to hypertensive heart disease and heart failure.
- Subendocardial ischemia is a key factor in myocardial injury and fibrosis.
- Hypertension management requires understanding microvascular contributions to cardiac damage.
Purpose of the Study:
- To evaluate the relationship between subendocardial perfusion and cardiac injury in hypertensive patients.
- To assess how subendocardial flow reserve correlates with cardiac structure and adverse cardiovascular events.
- To investigate the role of myocardial flow reserve in patients with hypertension and no obstructive coronary artery disease.
Main Methods:
- 13N-ammonia PET imaging assessed layer-specific blood flow and myocardial flow reserve (MFR).
- Consecutive hypertensive patients without flow-limiting coronary artery disease were studied.
- Subendocardial MFR (MFRsubendo) tertiles were compared for cardiac biomarkers, structure, and clinical outcomes.
Main Results:
- Lower MFRsubendo correlated with older age, diabetes, poorer renal function, and higher blood pressure.
- The lowest MFRsubendo tertile was associated with myocardial injury, increased left ventricular thickness, and volumes.
- Impaired MFRsubendo independently predicted major adverse cardiac and cerebrovascular events and heart failure hospitalization.
Conclusions:
- Impaired subendocardial MFR in hypertensive patients is linked to cardiovascular risk factors.
- Reduced MFRsubendo is associated with cardiac structural changes and elevated cardiac biomarkers.
- Subendocardial perfusion assessment is crucial for identifying hypertensive patients at higher risk for adverse clinical events.
Background:
Coronary microvascular dysfunction has been implicated in the development of hypertensive heart disease and heart failure, with subendocardial ischemia identified as a driver of sustained myocardial injury and fibrosis. We aimed to evaluate the relationships of subendocardial perfusion with cardiac injury, structure, and a composite of major adverse cardiac and cerebrovascular events consisting of death, heart failure hospitalization, myocardial infarction, and stroke.
Methods:
Layer-specific blood flow and myocardial flow reserve (MFR; stress/rest myocardial blood flow) were assessed by 13N-ammonia perfusion positron emission tomography 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).
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 wall thickness and volumes compared with the highest tertile. Relative to the highest tertile, low MFRsubendo was independently associated with an increased rate of major adverse cardiac and cerebrovascular events (adjusted hazard ratio, 2.99 [95% CI, 1.39-6.44]; P=0.005) and heart failure hospitalization (adjusted hazard ratio, 2.76 [95% CI, 1.04-7.32; P=0.042) over 1.1 (interquartile range, 0.6-2.8) years median follow-up.
Conclusions:
Among patients with hypertension without flow-limiting coronary artery disease, impaired MFRsubendo was associated with cardiovascular risk factors, elevated cardiac biomarkers, cardiac structure, and clinical events.
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