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Myocardial Blood Flow Reserve, Microvascular Coronary Health, and Myocardial Remodeling in Patients With Aortic
Fares Alahdab1, Ahmed I Ahmed1, Malek Nayfeh1
1Houston Methodist DeBakey Heart and Vascular Center Houston TX.
Insights
Aortic stenosis (AS) severity correlates with reduced myocardial flow reserve (MFR) and global longitudinal strain (GLS), indicating poorer coronary microvascular health. This highlights the importance of assessing MFR in AS patients, even without ischemia.
Area of Science:
- Cardiology
- Cardiovascular Imaging
- Medical Diagnostics
Background:
- Coronary microvascular function is crucial in coronary circulation and myocardial remodeling.
- Aortic stenosis (AS) may impact these processes.
- Understanding the relationship between myocardial blood flow and function in AS is important.
Purpose of the Study:
- To evaluate the relationship between myocardial blood flow and myocardial function in patients with AS.
- To compare these parameters in patients with AS, no AS, and aortic valve sclerosis.
- To assess the correlation between myocardial flow reserve (MFR) and left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS).
Main Methods:
- Included patients with resting transthoracic echocardiography and positron emission tomography myocardial perfusion imaging.
- Assessed left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), and myocardial flow reserve (MFR).
- Tracked major adverse cardiovascular events (MACE) including mortality, myocardial infarction, and revascularization.
Main Results:
- Increasing AS severity correlated with impaired MFR and GLS, even with normal perfusion.
- Significant associations were found between MFR, GLS, and LVEF.
- Patients with mild-to-moderate AS showed higher rates of impaired MFR and MACE compared to controls.
Conclusions:
- Worsening AS severity leads to decreased MFR and GLS, indicating impaired coronary microvascular health and myocardial remodeling.
- Positron emission tomography-derived MFR is independently correlated with LVEF and GLS.
- Prosthetic aortic valve patients exhibit a high prevalence of impaired MFR.
Background:
Coronary microvascular function and hemodynamics may play a role in coronary circulation and myocardial remodeling in patients with aortic stenosis (AS). We aimed to evaluate the relationship between myocardial blood flow and myocardial function in patients with AS, no AS, and aortic valve sclerosis.
Methods And Results:
We included consecutive patients who had resting transthoracic echocardiography and clinically indicated positron emission tomography myocardial perfusion imaging to capture their left ventricular ejection fraction, global longitudinal strain (GLS), and myocardial flow reserve (MFR). The primary outcome was major adverse cardiovascular event (all-cause mortality, myocardial infarction, or late revascularization). There were 2778 patients (208 with aortic sclerosis, 39 with prosthetic aortic valve, 2406 with no AS, and 54, 49, and 22 with mild, moderate, and severe AS, respectively). Increasing AS severity was associated with impaired MFR (P<0.001) and GLS (P<0.001), even when perfusion was normal. Statistically significant associations were noted between MFR and GLS, MFR and left ventricular ejection fraction, and MFR and left ventricular ejection fraction reserve. After a median follow-up of 349 (interquartile range, 116-662) days, 4 (7.4%), 5 (10.2%), and 6 (27.3%) patients experienced a major adverse cardiovascular event in the mild, moderate, and severe AS groups, respectively. In a matched-control analysis, patients with mild-to-moderate AS had higher rates of impaired MFR (52.9% versus 39.9%; P=0.048) and major adverse cardiovascular event (11.8% versus 3.0%; P=0.002).
Conclusions:
Despite lack of ischemia, as severity of AS increased, MFR decreased and GLS worsened, reflecting worse coronary microvascular health and myocardial remodeling. Positron emission tomography-derived MFR showed a significant independent correlation with left ventricular ejection fraction and GLS. Patients with prosthetic aortic valve showed a high prevalence of impaired MFR.
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