Particularities of coronary physiology in patients with atrial fibrillation: insights from combined pressure and flow indices measurements.

Background: Symptoms suggestive of myocardial ischemia are frequently encountered in patients with atrial fibrillation (AF) even in the absence of obstructive coronary artery disease. Nevertheless, an in-depth characterisation of coronary physiology in patients with AF is currently lacking. Objectives: We aim to provide an insight into the characteristics of coronary physiology in AF, by performing simultaneous invasive measurements of coronary flow- and pressure- indices in a real-life population of patients with AF and indication of coronary angiography. Methods: This is a prospective open label study including patients with permanent or persistent AF and indication of coronary angiography showing intermediate coronary stenosis requiring routine physiological assessment (n = 18 vessels from 14 patients). We measured FFR (fractional flow reserve), and Doppler-derived coronary flow indices, including CFR (coronary flow reserve) and HMR (hyperaemic microvascular resistance). Results: From the analysed vessels, 18/18 vessels (100%) presented a pathological CFR (<2.5), indicative of coronary microvascular dysfunction (CMD), and 3/18 (17%) demonstrated obstructive epicardial coronary disease (FFR ≤ 0.8). A large proportion of vessels (15/18; 83%) showed discordant FFR/CFR with preserved FFR and low CFR. 47% of the coronary arteries in patients with AF and non-obstructive epicardial coronary disease presented structural CMD (HMR ≥ 2.5 mmHg/cm/s), and were associated with high BMR and an impaired response to adenosine. Conversely, vessels from patients with AF and non-obstructive epicardial coronary disease with functional CMD (HMR < 2.5 mmHg/cm/s) showed higher bAPV. The permanent AF subpopulation presented increased values of HMR and BMR compared to persistent AF, while structural CMD was more often associated with persistent symptoms at 3 months, taking into account the limited sample size of our study. Conclusion: Our findings highlight a systematically impaired CFR in patients with AF even in the absence of obstructive epicardial coronary disease, indicative of CMD. In addition, patients with AF presented more prevalent structural CMD (HMR ≥ 2.5 mmHg/cm/s), characterized by reduced hyperaemic responses to adenosine, possibly interfering with the FFR assessment.

Assessment of Intracoronary Adenosine-Induced Hyperemia in Patients with Atrial Fibrillation in Comparison with Patients in Sinus Rhythm.

BACKGROUND: Fractional flow reserve (FFR) is routinely used to evaluate coronary stenosis in patients with atrial fibrillation (AF), although no studies currently address its reliability in this particular population. The clinical impact of correct assessment of coronary stenosis in AF is particularly high in light of the antithrombotic therapy imposed by both AF and coronary stenting. OBJECTIVES: Given the hemodynamic variability and microvascular dysfunction described in AF, the aim of this study was to evaluate the hyperemic response to intracoronary adenosine in AF in comparison with sinus rhythm (SR). METHODS AND RESULTS: This retrospective study included 36 patients in AF and 36 patients in SR. The hyperemic curves were derived in a subset of patients where the required information was available (n = 16 AF, n = 10 SR). AF patients presented a hyperemic response after intracoronary administration of adenosine, which was equivalent to SR in terms of magnitude and time to maximal hyperemia. CONCLUSION: There is equivalent hyperemic response in FFR-guided revascularization in AF versus SR population. Our findings support the use of FFR in evaluating intermediate coronary stenosis in AF.