Evolution Toward Non-Invasive Assessment of CMD

The study by Hillier and colleagues further strengthens the growing paradigm shift toward non-invasive assessment of coronary microvascular dysfunction (CMD) using advanced cardiac magnetic resonance (CMR) techniques (Hillier et al 2026). Over the last decade, the diagnostic approach to patients with ischaemia and non-obstructive coronary arteries (INOCA) has progressively evolved from predominantly invasive coronary function testing toward increasingly sophisticated imaging-based strategies capable of characterising both endothelial-dependent and endothelial-independent microvascular dysfunction.

Limitations of Invasive Coronary Function Testing

Traditionally, invasive acetylcholine provocation testing and adenosine-derived physiological indices have represented the reference standard for CMD evaluation. Nevertheless, these procedures remain time-consuming, technically demanding, and available only in highly specialized centers. In addition, invasive testing may be associated with patient discomfort and procedural risks, limiting its widespread implementation in routine clinical practice.

Quantitative Stress Perfusion CMR: A New Diagnostic Standard

In this context, quantitative stress perfusion CMR has emerged as one of the most promising non-invasive tools for the evaluation of microvascular angina (Zhou et al. 2021; Rahman et al. 2021). Modern pixel-wise myocardial blood flow mapping and myocardial perfusion reserve quantification enable objective identification of diffuse ischemia that frequently remains undetected by conventional visual perfusion analysis. Importantly, these techniques allow comprehensive assessment of coronary vasodilatory capacity without exposure to ionizing radiation (Rahman et al. 2021; Chiribiri et al. 2025).

Oxygenation-Sensitive CMR and Myocardial Ischaemia

Beyond perfusion imaging, oxygenation-sensitive CMR (OS-CMR) represents an exciting frontier in the field of coronary microvascular imaging. By exploiting endogenous blood oxygen level-dependent signal changes, OS-CMR provides direct insight into myocardial oxygenation and tissue-level ischemia without the need for gadolinium contrast administration. This approach may be particularly valuable for the assessment of endothelial dysfunction, where abnormalities in vasomotor regulation and oxygen delivery often precede overt perfusion impairment (Hillier et al. 2026).

Towards a Fully Non-Invasive Diagnostic Pathway

Although the most current studies are limited by relatively small sample sizes, single-center design, and lack of standardised acquisition and post-processing protocols, the present study demonstrated high diagnostic accuracy in identifying endothelial-dependent coronary microvascular disease. The increasing integration of quantitative perfusion imaging and oxygenation-sensitive CMR raises the possibility of a fully non-invasive diagnostic pathway for microvascular angina. 

Future Perspectives and Clinical Implications

Such a strategy could substantially reduce reliance on invasive testing while simultaneously improving patient accessibility and diagnostic reproducibility. Although further multi-center validation and standardization are still required, advanced CMR techniques are rapidly becoming central to the contemporary evaluation of coronary microvascular disease.