Retrospective comparison of Resting Full-cycle Ratio (RFR) and Fractional Flow Reserve (FFR) in a coronary artery disease cohort

Background The fractional flow reserve (FFR) is the gold standard for the assessment of the physiological severity of coronary artery disease. Measurement of FFR requires administration of a vasodilator (commonly adenosine) to achieve maximum hyperemia. The development of resting indices that do not require the administration of adenosine is of great importance. A novel hyperemia-free resting index is the “resting full cycle ratio” (RFR), which corresponds to the lowest pressure distal to the stenosis in relation to the aortic pressure during the entire cardiac cycle. The aim of the present study was to examine the diagnostic accuracy of RFR compared to FFR. Methods The study included consecutive patients undergoing pressure wire studies for standard indications at our university hospital from March 9, 2015 to February 15, 2019. Lesions with FFR ≤0.80 were classified as functionally significant. The RFR values were calculated retrospectively from the curves of the FFR measurements, using a point in time before adenosine administration, so that non-hyperemic resting conditions were present. Results A total of 635 patients with 733 coronary lesions were investigated using FFR. The average age of the subjects was 68.1±10.7 years. 459 (72.3%) were male. The distribution of the lesions was as follows: LAD: 444 (60.5%), RCA: 140 (19.1%), RCX: 127 (17.3%), RIM: 12 (1.6), LM: 6 (0.9%) and bypasses: 4 (0.5). Overall, the FFR and RFR values were 0.841±0.08 and 0.91±0.06. The RFR showed a significant correlation with the FFR (Table 1). Diagnostic accuracy of the RFR compared to the FFR was highest at a cut-off value of 0.89. This could be demonstrated using the receiver operating characteristic curve (Picture 1). In 408 measurements, coronary stenoses that were not hemodynamically relevant were found (FFR>0.8 and RFR>0.89). 164 measurements showed hemodynamically relevant coronary stenoses (FFR ≤0.8 and RFR ≤0.89). In 66 lesions, the FFR measurement showed hemodynamic relevance and the RFR measurement did not, whereas in 95 patients the RFR measurement showed hemodynamic relevance and the FFR values were normal. Conclusions The RFR as a new resting index has a significant correlation with the FFR after adenosine administration. In 22% of the measurements, a different therapeutic decision would have been made based on the RFR vs. the FFR. A randomized study should therefore investigate whether a RFR-guided approach is non-inferior to a FFR-guided approach in terms of avoiding cardiovascular complications. Funding Acknowledgement Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Abbott Laboratories

A Case Report of Neonatal Supraventricular Tachycardia Resolved with Single-Syringe Adenosine

Introduction: Supraventricular tachycardia (SVT) is a condition requiring emergency care in neonates. Case Report: We describe a successfully treated case of neonatal SVT in a four-week-old neonate using the novel adenosine administration method. This technique is potentially easier to facilitate and does not require equipment such as a stopcock. Adenosine 0.2 milligrams per kilogram was drawn up into a syringe containing 0.9% sodium chloride to a total volume of 3 milliliters. Once administered, the patient had near-immediate return to normal sinus rhythm without sequelae. Conclusion: This case demonstrates that the single-syringe method appears potentially safe and effective in neonates.

High-power radiofrequency ablation guided by ablation index for pulmonary vein isolation

Background: Proposed to facilitate pulmonary vein isolation (PVI), high-power ablation may cause extracardiac damage. This study evaluated the safety and efficacy of ablation index (AI) guided high-power ablation first in an animal model and subsequently in a clinical study.Methods:Outcomes of radiofrequency (RF) applications were compared in a swine ventricular endocardial model (n=10 each for 50W, 40W and 30W; AI=500), and in 100 consecutive patients with paroxysmal AF undergoing PVI (40W [last n=50] vs. 30 W [first n=50]; target AI=400/500 on posterior/anterior wall, respectively). Acute PV reconnection was assessed post adenosine administration 20 minutes after ablation.Results: In swine ventricular endocardial RF applications, use of 50W and 40W vs. 30W was associated with greater tissue lesion depth (5.06±0.16 and 4.38±0.13mm vs. 3.95±0.16mm; P<0.001) and smaller lesion maximum diameter (7.81±0.15 and 8.42±0.18mm vs. 9.08±0.15mm; P<0.001). Tissue necrosis caused by 50W vs. 40W and 30W was the deepest and largest (3.15±0.18mm vs. 2.71±0.17 and 2.42±0.13mm; and 5.58±0.18mm vs. 5.18±0.16 and 3.94±0.17mm; respectively; P<0.001). In PVI, use of 40W vs. 30W was associated with shorter procedure time (56.54±1.81min vs. 76.55±2.34min; p<0.001) and ablation time (35.85±14.87min vs. 51.01±17.99min; p<0.001); lower RF energy per point (909.02±354.57J vs. 1045±376.60J; p<0.001); higher first-pass PVI (87% vs. 72%; P<0.01); lower acute PV reconnection (22% vs. 41%; P<0.01); no complications in either group; and similar sinus rhythm maintenance at 12 months (92% vs. 84%; P=0.22).Conclusions: AI-guided high-power (40W) vs. conventional (30W) PVI was related to a reduced time for procedure and was considered safe, with diminished acute PV reconnection.

High- power radiofrequency ablation guided by ablation index for pulmonary vein isolation

Background Proposed to facilitate pulmonary vein isolation (PVI), high-power ablation may cause extracardiac damage. This study evaluated the safety and efficacy of ablation index (AI) guided high-power ablation first in an animal model and subsequently in a clinical study. Methods Outcomes of radiofrequency (RF) applications were compared in a swine ventricular endocardial model (n = 10 each for 50W, 40W and 30W; AI = 500), and in 100 consecutive patients with paroxysmal atrial fibrillation undergoing PVI (40W [last n = 50] vs. 30 W [first n = 50]; target AI = 400/500 on posterior/anterior wall, respectively). Acute PV reconnection was assessed post adenosine administration 20 minutes after ablation. Results In swine ventricular endocardial RF applications, use of 50W and 40W vs. 30W was associated with greater tissue lesion depth (5.06 ± 0.16 and 4.38 ± 0.13 mm vs. 3.95 ± 0.16 mm; P < 0.001) and smaller lesion maximum diameter (7.81 ± 0.15 and 8.42 ± 0.18 mm vs. 9.08 ± 0.15 mm; P < 0.001). Tissue necrosis caused by 50W vs. 40W and 30W was the deepest and largest (3.15 ± 0.18 mm vs. 2.71 ± 0.17 and 2.42 ± 0.13 mm; and 5.58 ± 0.18 mm vs. 5.18 ± 0.16 and 3.94 ± 0.17 mm; respectively; P < 0.001). In PVI, use of 40W vs. 30W was associated with shorter procedure time (56.54 ± 1.81 min vs. 76.55 ± 2.34 min; p < 0.001) and ablation time (35.85 ± 14.87 min vs. 51.01 ± 17.99 min; p < 0.001); lower RF energy per point (909.02 ± 354.57J vs. 1045 ± 376.60J; p < 0.001); higher first-pass PVI (87% vs. 72%; P < 0.01); lower acute PV reconnection (22% vs. 41%; P < 0.01); no complications in either group; and similar sinus rhythm maintenance at 12 months (92% vs. 84%; P = 0.22). Conclusions AI-guided high-power (40W) vs. conventional (30W) PVI was related to a reduced time for procedure and was considered safe, with diminished acute pulmonary vein reconnection.

6114Indications, procedural parameters, complications and consequences of fractional flow reserve measurements in a multicenter cohort

Background Determination of the Fractional Flow Reserve (FFR) has become part of routine clinical practice. Contemporary clinical use, consequences as well as complications in consecutive, large cohorts have not been thoroughly investigated. We report the results of the prospective Fractional Flow Reserve Fax Registry F (FR2) conducted in Germany. Purpose To systematically analyze indications, procedural parameters, complications and consequences of intracoronary pressure measurements in a large contemporary cohort. Methods Data of 2000 consecutive patients undergoing clinically indicated FFR, iFR or pd/pa measurements in 8 interventional centres in Germany were prospectively collected in a systematic fashion. Data included basic patient characteristics, procedural aspects of intracoronary pressure measurements, associated complications, visual stenosis degree, measurement results and treatment decisions. Results Mean patient age was 68±11 years, 73% of patients were male. Of all patients, 300 patients (15%) had an acute coronary syndrome (STEMI: 9; NSTEMI: 94; unstable angina: 197) and 1002 patients (50%) had undergone previous revascularization. A mean of 1.7±0.9 measurements were performed per patient, for which an average of 1.02 pressure wires were required (more than 1 wire in 64 patients). For all 3373 interrogated lesions, median stenosis degree was 60%. Vasodilator-free measurements were performed in 415/3373 cases (12%, iFR: 346; pd/pa: 69). For vasodilation, i.v. adenosine was used in 396 cases (13%), i.c. adenosine in 2628 cases (87%), and other drugs in 10 cases (0.3%). Measurement was performed before potential revascularization in 3232 cases (96%) and during or following PCI in 141 cases. In 2958 lesions analyzed by FFR, mean FFR was 0.87, with 588 FFR measurements ≤0.80 (19.8%). Median FFR values were higher for i.c than i.v. adenosine administration (0.88 vs. 0.84), but not significantly different after adjustment for stenosis degree. In 735 cases (20.2%), intracoronary pressure measurement was followed by revascularization measures, while in 2637 cases (79.8%), no revascularization or no further revascularization was performed. In 36 out of 117 stenoses visually estimated to be ≥90%, revascularization was deferred following pressure measurement (31%). In 75 out of 2958 lesions analyzed by FFR, revascularization was performed even though FFR was >0.80 (3%). Severe complications (vessel dissection or occlusion) occurred in 5 out of 2000 patients as a consequence of intracoronary pressure measurement, resulting in death of 1 patient. Conclusion In clinical practice, the majority of intracoronary pressure measurements are performed in stenoses of intermediate angiographic severity and revascularization is deferred in approximately 80% of lesions. Vasodilator-free measurements are infrequent and route of adenosine administration has no effect on results. Complication rate is low but not negligible. Acknowledgement/Funding Abbott Vascular