Prognostic value and characterization of functional microvascular assessment in subjects with chronic angina and non-obstructive coronary artery disease (ANOCA): Data from the MICRO Registry

Ornela Velollari (Mainz)1, M. Olschweski (Mainz)1, H. Ullrich-Daub (Mainz)1, G. Gagno (Triest)2, S. Daub (Mainz)1, J. Herzog (Mainz)1, M. Knorr (Mainz)1, P. Lurz (Mainz)1, T. Gori (Mainz)1

1Universitätsmedizin der Johannes Gutenberg-Universität Mainz Kardiologie 1, Zentrum für Kardiologie Mainz, Deutschland; 2Azienda Sanitaria Universitaria di Trieste and Department of Medical Surgical and Health Sciences Kardiologie Triest, Italien



Approximately 112 million people globally are affected by angina pectoris, 50% of patients undergoing coronary angiography do not have obstructive coronary artery disease. In this case coronary microvascular dysfunction (CMD) may be a relevant differential diagnosis, leading to hospitalization and impairment of life quality. Atherosclerosis risk factors influence the development of CMD. This analysis seeks to identify predictor factors for coronary vasomotion disorders to gain broader knowledge on pathological mechanisms related to microvascular dysfunction.

Keywords: coronary microvascular dysfunction; ANOCA; vasospastic angina

Methods: This study analyzed data from the MICRO-Registry, a prospective cohort study on coronary vasomotion disorders. Patients with symptoms of angina, at least CCS II and suspicion of microvascular dysfunction from September 2020 until October 2023, underwent invasive microvascular function assessment after ruling out obstructive CAD. Using a bolus-based thermodilution method, parameters such as IMR and CFR were acquired. We analyzed data on the characteristics and comorbidities for all patients with ANOCA and sub cohorts of microvascular angina and coronary spasm.


One-hundred and seventy-two patients (mean age 64.7 ± 10.9 years, 65% female) with symptoms of refractory angina e. chronic coronary syndrome (CCS II-IV) were recruited in the study. Thirty-three patients were diagnosed with coronary microvascular dysfunction, defined by a positive IMR, above 25 (mean IMR 37, 7 ±16, 4 and mean CFR 2.46 ± 0.9). Additionally, 30 patients displayed epicardial spasm and microvascular spasm during acetylcholine provocation testing.

Univariate regression analyses were performed to identify predictors of coronary microvascular dysfunction. Here patients with atrial fibrillation had 5x higher risk (OR=5.4, [IC 95%, 2.19-13.34], p<0.001) and patients with heart failure (whether HFpEF or HF(m)rEF) 3x higher risk (OR=3.2, [IC 95%, 1.21-8.63], p=0.024) of developing coronary microvascular dysfunction. Patients with CMD were older than patients without CMD (68 vs 63 years, p=0-013), in univariate regression analysis age was a significant predictor of coronary microvascular dysfunction (Exp (β) =1.047, [IC 95%, 1.01-1.09], p=0.016). In a multivariate regression analysis, atrial fibrillation was the only independent predictor factor for microvascular dysfunction (OR=4.71, [IC 95%, 1.73-12.], p=0.002).

Concerning vasospastic disorders (epicardial and microvascular spasm), univariate regression analysis showed that hypertension was a predictor for epicardial spasm (OR= 0.419, [IC 95%, 0.182-0.963], p=0.040) and prior PCI for microvascular spasm (OR=0.416, [IC 95%, 0.184-0.936], p=0.034).

Independent predictors of acetylcholine-induced pain (35%) included Diabetes mellitus (OR=3.673, [IC 95%, 1.545-8.730], p=0.003) and prior PCI (OR=2.222, [IC 95%, 1.135-4.351], p=0.020).


Patients with atrial fibrillation were associated with a significantly higher risk of developing coronary microvascular dysfunction. The exact underlying pathological mechanism is still unknown. In this cohort, cardiovascular risk factors such as heart failure, hypertension were predictive of CMD, highlighting the importance of risk factor management.

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