Prior registries have shown that 65% of patients with chronic coronary syndrome (CSS) and angina do not present obstructive atherosclerosis. This phenomenon, called myocardial ischemia with no obstructive coronary arteries (INOCA) is more common in women and has been associated with high hospitalization costs and diminished quality of life. INOCA patients can present microvascular dysfunction (CMD), spasm or both, which is why correctly identifying the underlying mechanism is crucial for adequate treatment.
CMD invasive assessment requires specific coronary wires to determine coronary flow reserve (CFR) and microvascular resistance (IMR). In addition, coronary angiogram slow flow (CSF) has long been an indirect marker of vasomotor disorders. CSF is generally defined as an angiographic visual estimation of TIMI 2 flow.
The relationship between TIMI 2 presence and CMD invasive diagnosis has not yet been looked at. The aim of this work presented by Harkin et al. is to determine whether this angiographic finding could be an effective tool for CMD identificaiton.
The study included symptomatic patients with stable ischemic cardiomyopathy from NYU Langone Health. It excluded those with ≥50% coronary obstruction, severe vascular disease or ejection fraction deterioration.
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Pressure Wire X was used for invasive measuring, together with thermodilution techniques (saline bolus and induced hyperemia), considering CFR <2.5 and IMR >25 as abnormal. CSF was defined as ≥3 cardiac cycles to opacify distal vessels with contrast.
A total 104 patients were included, mean age 61.5 años, 78.8% women. When looking at the total cohort, mean CFR was 3.6 (IQR, 2.5–4.7) and IMR 21 (IQR, 13.3–28.0). 24% of participants presented abnormal CFR, while 34.6% presented abnormal IMR, with total 48.1% CMD. The angiographic assessment showed 22.1% presented CSF. CSF patietns showed longer target vessel diameters (anterior descending – AD) vs those with no CSF (P<0.001).
There was no correlation between visual estimation of number of cardiac cycles (NCC) for correct distal AD filling and invasive measurement (r=0.16; P=0.10). Neither was there any correlation between NCC and CFR (r=0.04; P=0.68), while with IMR there was a positive, very mild correlation (r=0.24; P=0.01).
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When assessing the proportion of patients with CMD ivasive diagnosis, there were no significant differences between patients with or without CSF (56.5% vs 45.7%; P=0.358).
Conclusions
In patients with chronic coronary síndrome and INOCA who received invasive measurement of CFR and IMR, there was a mild correlation with IMR with the presence of coronary slow reflow, and no correlation with CFR. According to this study, CSF is only a finding, and it should be looked into invasively to confirm the presence of microvascular dysfunction.
Dr. Omar Tupayachi.
Member of the Editorial Board of SOLACI.org.
Original Title: Visual Estimates of Coronary Slow Flow Are Not Associated With Invasive Wire-Based Diagnoses of Coronary Microvascular Dysfunction.
Reference: Harkin KL, Loftspring E, Beaty W, Joa A, Serrano-Gomez C, Farid A, Hausvater A, Reynolds HR, Smilowitz NR. Visual Estimates of Coronary Slow Flow Are Not Associated With Invasive Wire Based Diagnoses of Coronary Microvascular Dysfunction. Circ Cardiovasc Interv. 2024 Jun;17(6):e013902. doi: 10.1161/CIRCINTERVENTIONS.123.013902. Epub 2024 Apr 7. PMID: 38583174; PMCID: PMC11187652.
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