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Peripheral Reactive Hyperemia Index and Coronary Microvascular Function in Women With no Obstructive CAD: The iPOWER
Marie Mide Michelsen1, Naja Dam Mygind2, Adam Pena3
1Department of Cardiology, Bispebjerg Hospital, University of Copenhagen, Denmark.
Insights
Digital reactive hyperemia index (RHI) does not indicate coronary microvascular dysfunction (CMD) in women. This vascular assessment likely identifies different pathologies than coronary flow velocity reserve (CFVR).
Area of Science:
- Cardiology
- Vascular Biology
- Diagnostic Imaging
Background:
- Coronary microvascular dysfunction (CMD) is an early cardiovascular disease marker.
- CMD involves complex coronary circulation abnormalities.
- Impaired reactive hyperemia index (RHI) suggests peripheral vascular dysfunction.
Purpose of the Study:
- To determine if digital RHI is a sensitive indicator of CMD.
- To investigate the association between RHI and coronary flow velocity reserve (CFVR).
Main Methods:
- 339 women with angina symptoms and no obstructive coronary artery disease were studied.
- Coronary flow velocity reserve (CFVR) measured via echocardiography during dipyridamole infusion.
- Digital reactive hyperemia index (RHI) assessed using digital pulse amplitude tonometry.
Main Results:
- No correlation found between CFVR and RHI (p=0.23).
- Mean RHI did not differ between CFVR categories (p=0.39).
- Low CFVR associated with older age and hypertension; impaired RHI linked to higher BMI, diabetes, and smoking.
Conclusions:
- RHI does not identify CMD as assessed by CFVR in women without obstructive coronary artery disease.
- RHI and CFVR likely reflect distinct vascular pathologies.
- Different cardiovascular risk factor associations suggest RHI and CFVR identify different aspects of vascular health.
Objectives:
This study investigated whether digital reactive hyperemia index (RHI) measured by digital pulse amplitude tonometry is a sensitive indicator of coronary microvascular dysfunction (CMD).
Background:
CMD is an early marker of cardiovascular disease. However, CMD is a complex diagnosis and consists of multiple abnormalities of the coronary circulation. Impaired RHI is a noninvasive measure of peripheral vascular dysfunction that can identify individuals with acetylcholine induced coronary vascular dysfunction. It is largely unknown whether there is also an association between RHI and the endothelial-independent aspect of CMD assessed as a coronary flow velocity reserve (CFVR).
Methods:
We included 339 women with chest pain suggestive of angina pectoris and a diagnostic invasive coronary angiogram without significant coronary artery stenosis (<50%). CFVR was measured by transthoracic pulsed wave Doppler echocardiography during dipyridamole infusion (0.84 mg/kg). RHI was assessed by digital pulse amplitude tonometry. Participants were categorized in 3 RHI and 3 CFVR groups. We examined the association between CFVR and RHI and the distribution of cardiovascular risk factors between the CFVR and RHI groups.
Results:
CFVR and RHI were successfully measured in 322 participants. Median CFVR was 2.3 (interquartile range: 2.0 to 2.8) and median RHI was 2.1 (interquartile range: 1.6 to 2.6). No correlation was found between CFVR and RHI (Spearman's rho = -0.067, p = 0.23), and mean RHI did not differ between CFVR categories (p = 0.39). Participants with low CFVR were significantly older and had a significantly greater burden of hypertension, whereas participants with an impaired RHI had a higher body mass index and were more likely to have diabetes and be current smokers.
Conclusions:
RHI does not identify individuals with CMD assessed as impaired CFVR by dipyridamole stress echocardiography in women with no obstructive coronary artery disease. The two methods are likely to identify different aspects of vascular pathology, as indicated by the different association with cardiovascular risk factors.
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