Key result
Angiographic coronary slow flow fails to identify invasive microvascular dysfunction in ANOCA patients.
Why the study?
The validity of angiographic coronary slow flow and myocardial blush grade for diagnosing coronary microvascular dysfunction has not been compared with invasive coronary functional testing.
Do angiographic findings of coronary slow flow and myocardial blush grade correlate with invasive testing for coronary microvascular dysfunction in patients with ANOCA?
Observational (n=304)
Do angiographic findings of coronary slow flow and myocardial blush grade correlate with invasive testing for coronary microvascular dysfunction in patients with ANOCA?
Absolute Event Rate: 8.6% vs 4.9%
p-value: p=0.23
Angiographic markers such as coronary slow flow and myocardial blush grade do not reliably predict coronary microvascular dysfunction in ANOCA patients, emphasizing the need for dedicated invasive functional testing.
Angiographic slow flow should not guide CMD diagnosis in ANOCA; leaves open whether dedicated invasive testing remains essential.
BACKGROUND: Angiographic coronary slow flow (CSF) has been correlated with coronary microvascular dysfunction (CMD) and abnormal myocardial blush grade (MBG) has been associated with worse outcomes in acute myocardial infarction. Their validity has not been compared with newer invasive forms of coronary functional CMD testing. Therefore, we aimed to investigate whether angiographic assessment of CSF and MBG correlate with gold-standard invasive assessments of CMD. METHODS: Using the Coronary Microvascular Disease Registry (NCT05960474), we identified patients with angina and non-obstructive coronary arteries (ANOCA) who underwent invasive coronary functional testing (CFT) between August 2021 and August 2024. CMD was defined as coronary flow reserve (CFR) < 2.5 with an index of microcirculatory resistance (IMR) > 25 using invasive bolus thermodilution technique. CSF was defined as > 3 cardiac cycles for distal opacification of vessels with contrast. Slow Thrombolysis in Myocardial Infarction frame count (TFC) was defined as a corrected frame count of > 25. MBG was categorized as abnormal (Grade 0 or 1). Rates of abnormal CSF and MBG were compared between the CMD-positive and negative groups. RESULTS: A total of 304 patients were included, of whom 81 (26.6%) were CMD positive. Patients were predominantly female (67.9 vs. 63.7%, p = 0.50) and slightly older (64.0 ± 11.3 vs. 60.6 ± 10.8 years, p = 0.02) with a lower BMI (28.5 ± 5.7 vs. 31.6 ± 6.9; p < 0.001) in the CMD positive group. Common comorbidities included hypertension, hyperlipidemia, and diabetes with a similar prevalence in both groups. There was no difference between CMD-positive and negative groups for CSF, (8.6% vs. 4.9%, p = 0.23) or slow cTFC (14.8% vs. 15.7%, p = 0.85). Additionally, the rate of abnormal MBG was similar in both groups (1.3% vs. 3.1%; p = 0.37). CONCLUSION: Our findings suggest that, while readily available and previously used for diagnosis, the angiographic findings of CSF and MBG do not reliably indicate the presence of CMD in ANOCA patients. Therefore, dedicated CFT should be pursued if there is clinical suspicion of CMD.
No takes yet. Share an insight, caveat, or question.
Hill et al. (2025) conducted an observational in Angina and non-obstructive coronary arteries (ANOCA) (n=304). Invasive coronary microvascular dysfunction (CMD) vs. No CMD (CMD negative) was evaluated on Angiographic coronary slow flow (CSF) (p=0.23). Angiographic coronary slow flow did not significantly differ between ANOCA patients with and without invasive coronary microvascular dysfunction (8.6% vs. 4.9%, p=0.23).
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: