Principles and pitfalls in coronary vasomotor function testing

BACKGROUND

Coronary vasomotor dysfunction can be diagnosed in a large proportion of patients with angina in the presence of non-obstructive coronary artery disease (ANOCA) using comprehensive protocols for coronary vasomotor function testing (CFT). Although consensus on diagnostic criteria for endotypes of coronary vasomotor dysfunction has been published, consensus on a standardised study testing protocol is lacking.

AIMS

In this review we provide an overview of the variations in CFT used and discuss the practical principles and pitfalls of CFT.

METHODS

For the purposes of this review, we assessed study protocols that evaluate coronary vasomotor response as reported in the literature. We compared these protocols regarding a number of procedural aspects and chose six examples to highlight the differences and uniqueness.

RESULTS

Currently, numerous protocols co-exist and vary in vascular domains tested, the manner in which to test these domains (e.g., preprocedural discontinuation of medication, provocative agent, solution, infusion time, and target artery) and techniques used for measurements (e.g., Doppler vs thermodilution technique).

CONCLUSIONS

This lack of consensus on a uniform functional testing protocol hampers both a broader clinical acceptance of the concepts of coronary vasomotor dysfunction, and the widespread adoption of such testing protocols in current clinical practice. Furthermore, the endotype of coronary vasomotor dysfunction might differ among the few specialised centres that perform CFT as a result of the use of different protocols.

Prognostic Implications of Individual and Combinations of Resting and Hyperemic Coronary Pressure and Flow Parameters

Background

Coronary pressure- and flow-derived parameters have prognostic value.

Objectives

This study aims to investigate the individual and combined prognostic relevance of pressure and flow parameters reflecting resting and hyperemic conditions.

Methods

A total of 1,971 vessels deferred from revascularization after invasive pressure and flow assessment were included from the international multicenter registry. Abnormal resting pressure and flow were defined as distal coronary pressure/aortic pressure ≤0.92 and high resting flow (1/resting mean transit time >2.4 or resting average peak flow >22.7 cm/s), and abnormal hyperemic pressure and flow as fractional flow reserve ≤0.80 and low hyperemic flow (1/hyperemic mean transit time <2.2 or hyperemic average peak flow <25.0 cm/s), respectively. The clinical endpoint was target vessel failure (TVF), myocardial infarction (MI), or cardiac death at 5 years.

Results

The mean % diameter stenosis was 46.8% ± 16.5%. Abnormal pressure and flow were independent predictors of TVF and cardiac death/MI (all P < 0.05). The risk of 5-year TVF or MI/cardiac death increased proportionally with neither, either, and both abnormal resting pressure and flow, and abnormal hyperemic pressure and flow (all P for trend < 0.001). Abnormal resting pressure and flow were associated with a higher rate of TVF or MI/cardiac death in vessels with normal fractional flow reserve; this association was similar for abnormal hyperemic pressure and flow in vessels with normal resting distal coronary pressure/aortic pressure (all P < 0.05).

Conclusions

Abnormal resting and hyperemic pressure and flow were independent prognostic predictors. The abnormal flow had an additive prognostic value for pressure in both resting and hyperemic conditions with complementary prognostic between resting and hyperemic parameters.