PET-based assessment of coronary microvascular dysfunction and its relation to plaque burden and vascular remodeling: integration with microvascular resistance reserve.

BACKGROUND

Coronary microvascular dysfunction (CMD) contributes to myocardial ischemia in patients with angina and non-obstructive coronary artery disease. Quantitative positron emission tomography (PET) allows noninvasive assessment of myocardial blood flow and identification of CMD.

OBJECTIVES

To investigate the association between PET-assessed coronary microvascular dysfunction (CMD), coronary plaque burden, and vascular remodeling, integrating microvascular resistance reserve (MRR).

METHODS

This post hoc analysis of the PACIFIC-1 trial included coronary arteries from symptomatic patients with suspected stable CAD who underwent [15O]water PET, coronary CT angiography (CTA), and invasive fractional flow reserve (FFR). Coronary arteries were categorized into three groups: non-ischemic vessels (normal FFR and hyperemic myocardial blood flow [hMBF], n = 352), CMD vessels (normal FFR but impaired hMBF, n = 88), and epicardial flow-limiting vessels (abnormal FFR, n = 159). MRR was calculated by integrating PET-derived coronary flow reserve with invasive FFR. AI-based CTA quantified plaque burden and remodeling.

RESULTS

Diameter stenosis and plaque burden increased progressively from non-ischemic to CMD to epicardial flow-limiting vessels (all P < 0.05). CMD vessels demonstrated the largest lumen volume (583.75 mm3 [IQR 337.02-754.30]) and lumen area (4.63 mm2 [IQR 3.77-6.67]) among the three groups (both P < 0.05). In non-ischemic vessels, noncalcified plaque burden was associated with worse microvascular function detected by MRR (B = -0.12, 95%CI [-0.21, -0.04], P = 0.006). In CMD vessels, remodeling index was independently associated with higher MRR after adjustment (B = 0.10, 95%CI [0.05, 0.15], P < 0.001).

CONCLUSIONS

CMD is associated with an intermediate atherosclerotic burden and paradoxical lumen enlargement, representing a distinct functional-structural phenotype defined by PET-derived microvascular dysfunction and CT-based plaque characteristics.

CLINICAL TRIAL REGISTRATION: URL: https://www.

CLINICALTRIALS: gov ; Unique identifier: NCT01521468.