Trial Design
Improving diagnosis and treatment of women with angina pectoris and microvascular disease: The iPOWER study design and rationale

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Background

The iPOWER study aims at determining whether routine assessment of coronary microvascular dysfunction (CMD) in women with angina and no obstructive coronary artery disease is feasible and identifies women at risk.

Methods

All women with angina referred to invasive angiographic assessment in Eastern Denmark are invited to join the study according to in- and exclusion criteria. Assessment includes demographic, clinical and psychosocial data, symptoms, electrocardiogram, blood- and urine samples and transthoracic echocardiography during rest and dipyridamol stress with measurement of coronary flow reserve (CFR) by Doppler of the left anterior descending artery. In substudies CMD will be assessed by positron emission tomography, peripheral endothelial function, magnetic resonance imaging—and computed tomography derived myocardial perfusion scans, angiographic corrected TIMI frame counts, advanced echocardiographic modalities at rest and during stress, and invasive measures of CFR and coronary vascular reactivity. The study will include 2000 women who will be followed for 5 years for cardiovascular outcomes.

Results

By May 2013, 1685 women have been screened, 759 eligible patients identified, 530 contacted, and 299 (56%) agreed to participate. Among the first 50 patients, Doppler CFR was successfully measured in 49 (98%).

Conclusions

Among women with suspected ischemic heart disease and no obstructive coronary artery disease, non-invasive Doppler CFR is feasible as a routine assessment. The study will provide information on methods to diagnose CMD and determine the prognostic value of routine non-invasive assessment of microvascular function. Future study will provide women identified with CMD participation in interventional substudies designed to test treatment strategies.

Section snippets

Background

Angina is the most common symptom of ischemic heart disease (IHD) among women but the correlation between luminal obstruction at coronary angiography (CAG) and angina is lower than among men.1., 2., 3., 4. More than half of women with angina have no obstructive coronary artery disease (CAD) (>50% luminal diameter stenosis in ≥1 epicardial coronary artery), twice as often as in men.4 Recent studies emphasize that contrary to previous understanding, many of these women have a poor prognosis in

Study objectives

The aim of the iPOWER study is to assess the prevalence of CMD and the value of clinically applicable diagnostic methods for its identification, to determine the prognostic importance of CMD, and, ultimately, to improve treatment of women with angina and no obstructive CAD.

Study design overview

This is a comprehensive multicentre study designed to improve diagnosis and treatment of women with angina and no obstructive coronary vessel disease. The study has 3 parts: a diagnostic component, a prognostic component, and a third component focusing on intervention. Through an alliance between departments of cardiology in Denmark we will apply combinations of functional, anatomical and biochemical methods to develop safe, accurate and cost-effective diagnostic approaches aimed at

Discussion

The preliminary iPOWER results indicate that the transthoracic echocardiographic Doppler-derived CFR is feasible as a routine assessment in women with angina and no angiographic epicardial stenosis. The current speed of patient inclusion in iPOWER is sufficient to reach the study goal of 2000 women included in the prospective study with an inclusion period of 3 years.

The clinical strategies currently pursued in diagnosis, risk stratification and treatment of patients with IHD focus on

Conclusion

The iPOWER study will be the largest study to date to systematically assess coronary microvascular function in women with angina and no obstructive IHD and will establish the role of CMD in risk stratification.

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