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.

Reliability of Fractional Flow Reserve and Instantaneous Wave-Free Ratio in Assessing Intermediate Coronary Stenosis in Patients With Atrial Fibrillation.

Despite the current use of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) for guiding revascularization in atrial fibrillation (AF), there is a lack of studies evaluating their reliability in this particular population. This retrospective study aimed to investigate the reliability of FFR and iFR in patients with AF. This retrospective study included all patients with AF undergoing FFR measurements (n = 45 vessels from 36 patients) at Brugmann University Hospital, Brussels, Belgium, between 2012 and 2020 or iFR (n = 18 vessels from 13 patients) and a corresponding number of patients with sinus rhythm (SR) randomly selected from the same period, benefiting from iFR (n = 20 vessels from 17 patients) or FFR (n = 50 vessels from 37 patients). Our main findings indicate that there is an increased beat-to-beat variability of individual iFR measures in patients with AF, compared with SR. In addition, the reproducibility of iFR on test-retest is low in patients with AF, leading to increased lesion reclassification (53.8% of lesions reclassified on 2 consecutive iFR measurements in AF vs 6.6% lesions reclassified in SR, p <0.05). In contrast, FFR seems to be more robust in evaluating coronary lesions in AF in terms of equivalent variability, reproducibility, and lesion reclassification observed in the SR population. In conclusion, this is the first study to evaluate the reliability of iFR and FFR in AF. Our findings raise caution in using iFR to guide revascularization in patients with AF, whereas FFR seems to be more robust in this population.

Leadless pacemaker implantation: An unexpected complication.

The leadless pacemaker is an emerging technology with high efficacy and reduced complications rates. However, due to its novel status, some pitfalls remain to be addressed. We report the case of a 91-year-old patient undergoing a Micra pacemaker implantation. During the procedure, the maneuvers required for the adequate deployment of the device led to damaging of the septal tricuspid leaflet, resulting in severe tricuspid regurgitation. This is a severe mechanical complication of the Micra implantation technique, not previously reported in literature. In light of the novelty of the leadless pacemaker, we should remain cautious with regards to potential unreported complications.

D-dimer blood concentrations to exclude left atrial thrombus in patients with atrial fibrillation.

OBJECTIVE: Left atrial (LA) thrombus is routinely excluded by transoesophageal echocardiography (TOE) before cardioversion for non-valvular atrial fibrillation (AF). In the D-dimer blood concentrations to exclude LA thrombus in patients with AF study, two D-dimer cut-offs were compared to exclude LA thrombus prior to cardioversion. One was fixed to 500 ng/mL (DD500), based on clinical practice where such values are commonly accepted to exclude a thrombus. The other cut-off was adjusted to 10 times the patient's age (DDAge), based on the cut-off used to exclude pulmonary embolism. METHODS: 142 consecutive patients with non-valvular AF aged 69.7±11.4 years (52% with paroxysmal AF) referred for precardioversion TOE to exclude LA thrombus were prospectively enrolled. D-dimers were measured at the time of TOE by an ELISA test. RESULTS: LA thrombus was excluded with TOE in 129 (91%) and confirmed in 13 (9%) patients. D-dimers were significantly lower in patients without LA thrombus (729±611 vs 2376±1081 ng/L; p<0.05). DDAge indicated absence of LA thrombus with higher specificity than DD500 (66.4% vs 50.4%; p<0.05). Both cut-offs were able to identify all 13 patients with LA thrombus (false negative 0%). Patients with D-dimers

Laser Doppler imaging evaluation of nitroglycerin patch application in systemic sclerosis patients.

Recent studies suggest the use of topical nitroglycerin (NTG) application in systemic sclerosis (SSc)-associated Raynaud phenomenon (RP). With the current study, we aimed to characterize for the first time the microvascular response to a NTG patch (Trinipatch® 5 mg/24 h) applied to the hand dorsum in patients with SSc using Laser Doppler imaging (LDI) at baseline and following a cold challenge. The study included 21 patients with SSc and 13 controls. Blood flow was evaluated by LDI at the level of the fingertips and metacarpus. Microvascular morphology was evaluated by nailfold capillaroscopy (NC). LDI revealed decreased fingertip baseline perfusion and a stronger vasoconstrictor response to a cold challenge in patients with SSc versus control. Metacarpal application of a NTG patch led to an increase in blood flow and hand temperature in patients with SSc. Furthermore, NTG administration led to a faster reperfusion after cold challenge. Correlation analyses revealed that the magnitude of the vasodilatory response was inversely related to baseline fingertip perfusion and hand temperature, but unrelated to the number of capillaries/mm assessed using NC. In conclusion, we provide evidence of a vasodilatory reaction following NTG patch application in patients with SSc using LDI and a protective effect against cold challenge. The magnitude of the response to NTG was related to functional, but not structural features. Our results support a further evaluation of the NTG patch as a possible therapeutic agent in SSc-associated RP.