Inter-scan Reproducibility of Cardiovascular Magnetic Resonance Imaging-Derived Myocardial Perfusion Reserve Index in Women with no Obstructive Coronary Artery Disease

Examining the Disproportionate Burden of Microvascular Disease in Women

Purpose of Review

Microvascular dysfunction (MD) is a systemic condition implicated in a wide range of pathologies, including ischemic heart disease (IHD), stroke, chronic kidney disease (CKD), dementia, pulmonary arterial hypertension (PAH), and pregnancy complications. MD encompasses conditions characterized by small-vessel obstruction, impaired oxygen delivery, defective clearance of cellular waste, and inadequate gas exchange, ultimately leading to tissue damage and organ dysfunction. This review identifies the role of MD in the pathogenesis of a variety of diseases and across organ systems. It highlights the disproportionate burden of MD in women, with a focus on sex-specific risk factors, especially pregnancy.

Recent Findings

In recent years, there has been increased recognition of the role of MD in the pathogenesis of both cardiac and non-cardiac diseases. Advances in imaging modalities, such as coronary flow reserve assessment and endothelial function testing, have improved the detection of microvascular dysfunction across organ systems. Studies have also highlighted the connection between MD and systemic inflammation, oxidative stress, and hormonal influences, particularly in women. Emerging research suggests that pregnancy-related complications, including preeclampsia and gestational hypertension, may serve as early markers of long-term microvascular dysfunction and cardiovascular disease risk.

Summary

This review focuses on coronary microvascular dysfunction (CMD) in women, with additional discussion of endothelial and microvascular dysfunction in the renovascular, cerebrovascular, and pulmonary arterial systems. This review describes diagnostic and therapeutic approaches for MD in diverse disease contexts and emphasizes the critical need for research to advance diagnostic tools and therapeutic strategies tailored to the unique needs of women.

The spectrum and systemic associations of microvascular dysfunction in the heart and other organs

Microvascular dysfunction (MVD) contributes to several conditions that increase morbidity and mortality, including ischemic heart disease, heart failure, dementia, chronic kidney disease and hypertension. Consequently, MVD imposes a substantial burden on healthcare systems worldwide. In comparison to macrovascular dysfunction, MVD has been incompletely investigated, and it remains uncertain whether MVD in an organ constitutes a distinct pathology or a manifestation of a systemic disorder. Here, we summarize and appraise the techniques that are used to diagnose MVD. We review the disorders of the heart, brain and kidneys in which the role of MVD has been highlighted and summarize evidence hinting at a systemic or multi-organ nature of MVD. Finally, we discuss the benefits and limitations of implementing MVD testing in clinical practice with a focus on new interventions that are beginning to emerge.

Temporal Trends in Angina, Myocardial Perfusion, and Left Ventricular Remodeling in Women With No Obstructive Coronary Artery Disease Over 1-Year Follow-Up: Results From WISE-CVD

Background Women with ischemia and no obstructive coronary artery disease are increasingly recognized and found to be at risk for major adverse cardiovascular events. Methods and Results In 214 women with suspected ischemia and no obstructive coronary artery disease who completed baseline and 1-year follow-up vasodilatory stress cardiac magnetic resonance imaging, we investigated temporal trends in angina (Seattle Angina Questionnaire [SAQ]), myocardial perfusion reserve index, blood pressure, and left ventricular (LV) remodeling and function from baseline to 1-year follow-up and explored associations between these different parameters. We observed concordant positive trends in 4/5 SAQ domains, SAQ-7, myocardial perfusion reserve index, blood pressure, LV mass, and LV mass-to-volume ratio. There was no association between SAQ-7 improvement and myocardial perfusion reserve index improvement over 1-year follow-up (P=0.1). Higher indexed LV end-diastolic volume and time to peak filling rate at baseline were associated with increased odds of clinically relevant SAQ-7 improvement (odds ratio [OR], 1.05; 95% CI, 1.0-1.1; and OR, 2.40; 95% CI, 1.1-5.0, respectively). Hypertension was associated with decreased odds of SAQ-7 improvement (OR, 0.41; 95% CI, 0.19-0.91). Conclusions In women with ischemia and no obstructive coronary artery disease clinically treated with cardiac medications over 1 year, we observed concurrent temporal trends toward improvement in SAQ, myocardial perfusion reserve index, blood pressure, LV mass, and LV mass-to volume ratio. We showed that abnormalities in LV morphology and diastolic function at baseline were predictive of clinically significant improvement in angina at follow-up, whereas history of hypertension was associated with lower odds. Future studies are needed to assess the mechanisms and treatments responsible for the improvements we observed. Registration URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT02582021.

Impact of caffeine on myocardial perfusion reserve assessed by semiquantitative adenosine stress perfusion cardiovascular magnetic resonance

BACKGROUND

Adenosine is used in stress perfusion cardiac imaging to reveal myocardial ischemia by its vasodilator effects. Caffeine is a competitive antagonist of adenosine. However, previous studies reported inconsistent results about the influence of caffeine on adenosine's vasodilator effect. This study assessed the impact of caffeine on the myocardial perfusion reserve index (MPRI) using adenosine stress cardiovascular magnetic resonance imaging (CMR). Moreover, we sought to evaluate if the splenic switch-off sign might be indicative of prior caffeine consumption.

METHODS

Semiquantitative perfusion analysis was performed in 25 patients who underwent: 1) caffeine-naïve adenosine stress CMR demonstrating myocardial ischemia and, 2) repeat adenosine stress CMR after intake of caffeine. MPRI (global; remote and ischemic segments), and splenic perfusion ratio (SPR) were assessed and compared between both exams.

RESULTS

Global MPRI after caffeine was lower vs. caffeine-naïve conditions (1.09 ± 0.19 vs. 1.24 ± 0.19; p <  0.01). MPRI in remote myocardium decreased by caffeine (1.24 ± 0.19 vs. 1.49 ± 0.19; p <  0.001) whereas MPRI in ischemic segments (0.89 ± 0.18 vs. 0.95 ± 0.23; p = 0.23) was similar, resulting in a lower MPRI ratio (=remote/ischemic segments) after caffeine consumption vs. caffeine-naïve conditions (1.41 ± 0.19 vs. 1.64 ± 0.35, p = 0.01). The SPR was unaffected by caffeine (SPR 0.38 ± 0.19 vs. 0.38 ± 0.18; p = 0.92).

CONCLUSION

Caffeine consumption prior to adenosine stress CMR results in a lower global MPRI, which is driven by the decreased MPRI in remote myocardium and underlines the need of abstinence from caffeine. The splenic switch-off sign is not affected by prior caffeine intake.