Utilizing Invasive Coronary Functional Testing in a Coronary Microvascular and Vasomotor Dysfunction Program: Methods and Considerations

Abstract

Background: Coronary microvascular and vasomotor dysfunction (CMVD) is associated with a threefold increased risk of major adverse cardiovascular events (MACE) and is the primary mechanism responsible for angina/ischemia in patients with nonobstructive coronary artery disease (ANOCA/INOCA). Proper assessment for CMVD is vital to provide targeted treatment and improve patient outcomes. Invasive coronary functional testing (ICFT) is the "gold standard," for CMVD assessment and can be used to diagnose all endotypes. However, there is a lack of standardization for ICFT protocols and use in the treatment of CMVD.

Aims: To provide a comprehensive overview of ICFT protocols utilized at the Christ Hospital Womens Heart Center (TCH-WHC).

Methods: Here, we outline our standard operating procedures for ICFT utilized at TCH-WHC, including the procedures two main methods: Doppler and Thermodilution. We describe our structured approach for ICFT referral and postdiagnostic clinical management utilized at The Christ Hospital Women's Heart Center (TCH-WHC) CMVD program. We then quantified how ICFT has contributed to growth of the TCH-WHC.

Results: From October of 2020 until July of 2024, a total of 422 patients have undergone ICFT at TCH-WCH, 64% were performed via the Doppler protocol and 36% were performed via the Thermodilution protocol. Based on exclusive endotype categories, 19% had an endothelial-independent CMD alone, 19% had endothelial-dependent CMD or microvascular VSA alone, 3% had epicardial VSA alone, 42% had mixed disease (any combination of the above categories), and 17% had a normal ICFT.

Conclusions: ICFT provides opportunity to provide diagnostic clarity and optimize medical treatment for CMVD. TCH-WHC's structured approach for ICFT referral and protocol for conducting comprehensive ICFT which has been vital for the growth of our specialized CMVD program.

Keywords: ACS—ACS/NSTEMI; ACS—acute coronary syndrome; CORB—coronary blood flow/physiology/microvascular function.

FIGURE 1 ∣

Diagnostic approach and referral to invasive coronary functional testing in ANOCA/INOCA patients. BB, beta blockers; CCB, calcium channel blockers; RAS-I, renin angiotensin aldosterone system inhibitors.

FIGURE 2 ∣

Overview of invasive coronary functional testing protocol and interpretation of results utilizing Doppler method.

FIGURE 3 ∣

Overview of invasive coronary functional testing protocols and interpretation of results utilizing thermodilution method.

FIGURE 4 ∣

Targeted treatment therapy based coronary functional testing diagnosis.

FIGURE 5 ∣

Breakdown of ICFT endotype diagnoses based on exclusive categories. Mixed disease represents patients with an abnormality in more than one of the listed categories.