Affiliation:
1. School of Cardiovascular Medicine and Sciences British Heart Foundation Centre of Excellence and National Institute for Health Research Biomedical Research Centre, King’s College London London UK
Abstract
Background
Guidelines recommend that coronary slow flow phenomenon (CSFP), defined as corrected thrombolysis in myocardial infarction frame count (CTFC)
>
$$ > $$
27, can diagnose coronary microvascular dysfunction (CMD) in patients with angina and nonobstructed coronary arteries. CSFP has also historically been regarded as a sign of coronary endothelial dysfunction (CED). We sought to validate the utility of CTFC, as a binary classifier of CSFP and as a continuous variable, to diagnose CMD and CED.
Methods and Results
Patients with angina and nonobstructed coronary arteries had simultaneous coronary pressure and flow velocity measured using a dual sensor‐tipped guidewire during rest, adenosine‐mediated hyperemia, and intracoronary acetylcholine infusion. CMD was defined as the inability to augment coronary blood flow in response to adenosine (coronary flow reserve <2.5) and CED in response to acetylcholine (acetylcholine flow reserve ≤1.5); 152 patients underwent assessment using adenosine, of whom 82 underwent further acetylcholine testing. Forty‐six patients (30%) had CSFP, associated with lower flow velocity and higher microvascular resistance as compared with controls (16.5
±
$$ \pm $$
6.9 versus 20.2
±
$$ \pm $$
6.9 cm/s;
P
=0.001 and 6.26
±
$$ \pm $$
1.83 versus 5.36
±
$$ \pm $$
1.83 mm Hg/cm/s;
P
=0.009, respectively). However, as a diagnostic test, CSFP had poor sensitivity and specificity for both CMD (26.7% and 65.2%) and CED (21.1% and 56.0%). Furthermore, on receiver operating characteristics analyses, CTFC could not predict CMD or CED (area under the curve, 0.41 [95% CI, 0.32%–0.50%] and 0.36 [95% CI, 0.23%–0.49%], respectively).
Conclusions
In patients with angina and nonobstructed coronary arteries, CSFP and CTFC are not diagnostic of CMD or CED. Guidelines supporting the use of CTFC in the diagnosis of CMD should be revisited.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine
Cited by
24 articles.
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