Electrophysiological cardiovascular MR: procedure-ready mesh model generation for interventional guidance based on non-selective excitation compressed sensing whole heart imaging.

Fully CMR-guided electrophysiological interventions (EP-CMR) have recently been introduced but data on the optimal CMR imaging protocol are scarce. This study determined the clinical utility of 3D non-selective whole heart steady-state free precession imaging using compressed SENSE (nsWHcs) for automatic segmentation of cardiac cavities as the basis for targeted catheter navigation during EP-CMR cavo-tricuspid isthmus ablation. Fourty-two consecutive patients with isthmus-dependent right atrial flutter underwent EP-CMR radiofrequency ablations. nsWHcs succeeded in all patients (nominal scan duration, 98 ± 10 s); automatic segmentation/generation of surface meshes of right-sided cavities exhibited short computation times (16 ± 3 s) with correct delineation of right atrium, right ventricle, tricuspid annulus and coronary sinus ostium in 100%, 100%, 100% and 95%, respectively. Point-by-point ablation adhered to the predefined isthmus line in 62% of patients (26/42); activation mapping confirmed complete bidirectional isthmus block (conduction time difference, 136 ± 28 ms). nsWHcs ensured automatic and reliable 3D segmentation of targeted endoluminal cavities, multiplanar reformatting and image fusion (e.g. activation time measurements) and represented the basis for precise real-time active catheter navigation during EP-CMR ablations of isthmus-dependent right atrial flutter. Hence, nsWHcs can be considered a key component in order to advance EP-CMR towards the ultimate goal of targeted substrate-based ablation procedures.

Validation of a novel smartphone-based photoplethysmographic method for ambulatory heart rhythm diagnostics: the SMARTBEATS study.

AIMS: In the current guidelines, smartphone photoplethysmography (PPG) is not recommended for diagnosis of atrial fibrillation (AF), without a confirmatory electrocardiogram (ECG) recording. Previous validation studies have been performed under supervision in healthcare settings, with limited generalizability of the results. We aim to investigate the diagnostic performance of a smartphone-PPG method in a real-world setting, with ambulatory unsupervised smartphone-PPG recordings, compared with simultaneous ECG recordings and including patients with atrial flutter (AFL). METHODS AND RESULTS: Unselected patients undergoing direct current cardioversion for treatment of AF or AFL were asked to perform 1-min heart rhythm recordings post-treatment, at least twice daily for 30 days at home, using an iPhone 7 smartphone running the CORAI Heart Monitor PPG application simultaneously with a single-lead ECG recording (KardiaMobile). Photoplethysmography and ECG recordings were read independently by two experienced readers. In total, 280 patients recorded 18 005 simultaneous PPG and ECG recordings. Sufficient quality for diagnosis was seen in 96.9% (PPG) vs. 95.1% (ECG) of the recordings (P < 0.001). Manual reading of the PPG recordings, compared with manually interpreted ECG recordings, had a sensitivity, specificity, and overall accuracy of 97.7%, 99.4%, and 98.9% with AFL recordings included and 99.0%, 99.7%, and 99.5%, respectively, with AFL recordings excluded. CONCLUSION: A novel smartphone-PPG method can be used by patients unsupervised at home to achieve accurate heart rhythm diagnostics of AF and AFL with very high sensitivity and specificity. This smartphone-PPG device can be used as an independent heart rhythm diagnostic device following cardioversion, without the requirement of confirmation with ECG.

Peak frequency mapping of atypical atrial flutter.

INTRODUCTION: Peak frequency (PF) mapping is a novel method that may identify critical portions of myocardial substrate supporting reentry. The aim of this study was to describe and evaluate PF mapping combined with omnipolar voltage mapping in the identification of critical isthmuses of left atrial (LA) atypical flutters. METHODS AND RESULTS: LA omnipolar voltage and PF maps were generated in flutter using the Advisor HD-Grid catheter (Abbott) and EnSite Precision Mapping System (Abbott) in 12 patients. Normal voltage was defined as ≥0.5 mV, low-voltage as 0.1-0.5 mV, and scar as <0.1 mV. PF distributions were compared with ANOVA and post hoc Tukey analyses. The 1 cm radius from arrhythmia termination was compared to global myocardium with unpaired t-testing. The mean age was 65.8 ± 9.7 years and 50% of patients were female. Overall, 34 312 points were analyzed. Atypical flutters most frequently involved the mitral isthmus (58%) or anterior wall (25%). Mean PF varied significantly by myocardial voltage: normal (335.5 ± 115.0 Hz), low (274.6 ± 144.0 Hz), and scar (71.6 ± 140.5 Hz) (p < .0001 for all pairwise comparisons). All termination sites resided in low-voltage regions containing intermediate or high PF. Overall, mean voltage in the 1 cm radius from termination was significantly lower than the remaining myocardium (0.58 vs. 0.95 mV, p < .0001) and PF was significantly higher (326.4 vs. 245.1 Hz, p < .0001). CONCLUSION: Low-voltage, high-PF areas may be critical targets during catheter ablation of atypical atrial flutter.

A matching-adjusted indirect comparison of results from REDUCE and RESPECT-two randomized trials on patent foramen ovale closure devices to prevent recurrent cryptogenic stroke.

AIMS: Two randomized clinical trials, REDUCE and RESPECT, demonstrated that patent foramen ovale (PFO) closure in combination with antithrombotic therapy was more effective for the prevention of recurrent ischemic stroke compared with antithrombotic therapy alone. The aim of this study was to determine the relative efficacy and safety of the PFO closure devices used in REDUCE (HELEX and CARDIOFORM Septal Occluders) compared with the device used in RESPECT (Amplatzer PFO Occluder). METHODS: An unanchored matching-adjusted indirect comparison (MAIC) of the PFO closure arms of the REDUCE and RESPECT trials was performed using patient-level data from REDUCE weighted to match baseline characteristics from RESPECT. Comparisons of the following outcomes were made between the devices assessed in the trials: risk of recurrent ischemic stroke; recurrent ischemic stroke one year after randomization; any serious adverse event (SAE) related to the procedure or device; and atrial fibrillation or atrial flutter as an SAE related to the procedure or device. RESULTS: After conducting the MAIC, baseline characteristics were well-matched between the two trials. Compared to RESPECT, PFO closure using the devices from REDUCE resulted in a hazard ratio of 0.46 (95% confidence interval [CI] 0.15-1.43; p = 0.17) for the risk of recurrent stroke. For the recurrence of stroke after one year, SAE related to the procedure or device, and atrial fibrillation or atrial flutter as SAE related to the procedure or device, the MAIC resulted in a rate difference of -0.68 (95%CI -2.06 to 0.70; p = .34), -1.29 (95%CI -3.82 to 1.25; p = .32), and -0.19 (95%CI -1.16 to 0.78; p = .71), respectively. These findings were consistent across scenario analyses. CONCLUSIONS: This MAIC analysis found no statistically significant differences in efficacy and safety outcomes between PFO closure with the HELEX and CARDIOFORM Septal Occluders versus the Amplatzer PFO Occluder, as used in the REDUCE and RESPECT trials.

The individual efficacy and safety of medical devices used for patent foramen ovale (PFO) closure in patients with stroke of unknown origin has been demonstrated in two independent trials: REDUCE (using the HELEX Septal Occluder and the CARDIOFORM Septal Occluder) and RESPECT (using the Amplatzer PFO Occluder). In the absence of a direct head-to-head trial for these devices, indirect treatment comparisons offer an alternative to assess their relative efficacy and safety. This study used a matching-adjusted indirect comparison to demonstrate that there were no significant differences between the devices used for PFO closure in the REDUCE and RESPECT trials in terms of safety outcomes.

Sensitivity and specificity of handheld one lead ECG detecting atrial fibrillation in an outpatient clinic setting.

AIMS: To validate the sensitivity and specificity of the Zenicor One handheld ECG device for detection of atrial fibrillation in an outpatient clinical setting. METHODS AND RESULTS: Patients attending outpatient clinics at Danderyd Hospital (n = 220) were examined with one lead handheld ECG immediately after standard care 12­lead ECG recording. Twelve recordings were excluded (atrial flutter or pacing) or missing. The recordings were dichotomously categorized as "atrial fibrillation" or "not atrial fibrillation" by two senior cardiologists. In cases of diverging interpretations, a third senior cardiologist had the deciding vote. Sensitivity and specificity in diagnosing atrial fibrillation was calculated with 12­lead ECG as gold standard. Sensitivity and specificity for diagnosis of atrial fibrillation with one lead handheld ECG and 12­lead ECG as gold standard was 98% and 99% respectively. CONCLUSION: In a health-care outpatient setting, Zenicor One handheld ECG had high sensitivity and specificity for detection of atrial fibrillation when compared with 12­lead ECG.

When a little flutter gets a bit too exciting .

A middle-aged man with no previous cardiac history was admitted to the hospital being treated for thigh cellulitis, during his stay he developed palpitations and tachycardia which on initial ECG showed atrial flutter with a 2:1 AV block and evidence of an accessory pathway. He was subsequently given AV nodal blocking agents in the form of beta-blockers (bisoprolol) to slow his heart rate down; unfortunately, this led to hemodynamic instability due to 1:1 conduction of the atrial flutter down the accessory pathway. This case report demonstrates the importance of recognising pre-excitation on an ECG and the potential adverse effect of administering AV nodal blockade.

Incidence and patterns of atrial fibrillation after catheter ablation of typical atrial flutter-the FLUTFIB study.

AIMS: In patients with atrial flutter (AFL), ablation of the cavotricuspid isthmus (CTI) is a highly effective procedure to prevent AFL recurrence, but atrial fibrillation (AF) may occur during follow-up. The presented FLUTFIB study was designed to identify the exact incidence, duration, timely occurrence, and associated symptoms of AF after CTI ablation using continuous cardiac monitoring via implantable loop recorders. METHODS AND RESULTS: One hundred patients with AFL without prior AF diagnosis were included after CTI ablation (mean age 69.7 ± 9.7 years, 18% female) and received an implantable loop recorder for AF detection. After a median follow-up of 24 months 77 patients (77%) were diagnosed with AF episodes. Median time to first AF occurrence was 180 (43-298) days. Episodes lasted longer than 1 h in most patients (45/77, 58%). Forty patients (52%) had AF-associated symptoms.Patients with and without AF development showed similar baseline characteristics and neither HATCH- nor CHA2DS2-VASc scores were predictive of future AF episodes. Oral anticoagulation (OAC) was stopped during FU in 32 patients (32%) and was re-initiated after AF detection in 15 patients (15%). No strokes or transient ischaemic attack episodes were observed during follow-up. CONCLUSION: This study represents the largest investigation using implantable loop recorders (ILRs) to detect AF after AFL ablation and shows a high incidence of AF episodes, most of them being asymptomatic and lasting longer than 1 h. In anticipation of trials determining the duration of AF episodes that should trigger OAC initiation, these results will help to guide anticoagulation management after CTI ablation.

Posttransplant atrial fibrillation: Evidence of early posttransplant recipient-to-donor atrioatrial connections.

INTRODUCTION: Atrial fibrillation and atrial flutter originating from the donor s heart is a commonly reported complication post heart transplant. Atrial tachyarrhythmia originating from the recipient s heart, propagated through recipient-to-donor connections, is rare with only few cases reported in the literature; most reported cases from our review occur years post-transplant. CASE: A 47-year-old male presented with atrial tachycardia 6 months post heart transplant. Electrophysiologic study demonstrated atrial fibrillation originating from native heart and propagated through atrio-atrial connections to the donor heart. This arrhythmia was successfully terminated with radiofrequency ablation. CONCLUSION: Atrio-atrial connection between recipient and donor can form as early as a few months post heart transplant. Radiofrequency ablation appears to be an effective treatment for atrial fibrillation propagated through donor-to-recipient connections.

Radiofrequency catheter ablation for pulmonary hypertension patients with atrial flutter.

AIMS: We aimed to evaluate the effects of radiofrequency catheter ablation (RFCA) and the factors influencing mortality after RFCA in patients with pulmonary hypertension (PH) and atrial flutter (AFL). METHODS AND RESULTS: Fifty-eight consecutive PH patients with AFL who underwent an electrophysiological study and RFCA between April 2013 and August 2021 were selected for this study. In the study population, pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD) was the most common type of PH (n = 34, 59%), followed by idiopathic pulmonary arterial hypertension (IPAH) (n = 19, 33%). Typical atrial flutter was the most common type of atrial flutter (n = 50, 86.2%). Sinus rhythm was restored in 53 (91.4%) patients during RFCA. After a mean follow-up of 33.8 months, AFL recurred in a total of 22 patients. Nine of them underwent repeat RFCA, and the site of the repeat ablation was not exactly the same as the first. At a median follow-up of 34.6 months after the last ablation, none of the patients who underwent repeat RFCA experienced AFL recurrence, and all of these patients survived. There were no procedure-related complications during hospitalization or follow-up. Univariate Cox regression analysis suggested that AFL recurrence after the last ablation was not associated with all-cause mortality. NT-proBNP (HR: 1.00024, 95% CI: 1.00008-1.00041, P = 0.004), pulmonary artery systolic pressure (PASP) (HR: 1.048, 95% CI: 1.020-1.076, P = 0.001), and IPAH (vs. PAH-CHD, HR: 7.720, 95% CI: 1.437-41.483, P = 0.017) were independent predictors of all-cause mortality in PH patients with AFL after RFCA. Receiver operating characteristic (ROC) curve analysis revealed that the area under the curve (AUC) of PASP for predicting all-cause mortality was 0.708. There was no significant difference in the Kaplan-Meier curves for all-cause mortality between patients with AFL recurrence after the last ablation and those without recurrence (P = 0.851). Patients with higher PASP (≥110 mmHg) and IPAH showed the lower survival rate in Kaplan-Meier curves. CONCLUSION: Repeat ablation was safe and feasible in patients with recurrent AFL and can maintain sinus rhythm. AFL recurrence was not associated with all-cause mortality, and patients with high PASP or IPAH were at higher risk for adverse outcomes.

Gender Differences With Ibutilide Effectiveness and Safety in Cardioversion of Atrial Fibrillation.

INTRODUCTION: Few studies have examined the use of ibutilide in noncardiac surgical populations. Our study considered the effectiveness and safety of ibutilide in cardioversion of atrial fibrillation (AF) in medical and surgical intensive care patients. METHODS: A retrospective chart review was performed for patients with a confirmed diagnosis of AF who were hemodynamically stable and received ibutilide after the initial diagnosis. Patients were administered 1 mg of ibutilide fumarate intravenous for 10 min with a second dose administered if AF persisted after 30 min. Patients were pretreated with intravenous magnesium sulfate if their blood magnesium level was <2 mg/dL. RESULTS: Fifty seven total female patients and 99 male patients received ibutilide. Females had an 88% conversion rate to normal sinus rhythm (NSR) compared to 68% in males (P = 0.008). A 70% successful return to NSR was observed in patients from all groups pretreated with magnesium sulfate (P = 0.045). One year after discharge, 74% of the patients stayed in the NSR. CONCLUSIONS: Within our population, pretreatment with magnesium sulfate followed by ibutilide was associated with increased conversion to NSR. Additionally, we noted that females had a higher conversion rate to NSR compared to males, regardless of whether they were pretreated with magnesium sulfate.

Atrial flutter complicating acute respiratory distress syndrome (ARDS): A rare case report.

RATIONALE: This case report addresses a unique instance of atrial flutter complicating acute respiratory distress syndrome (ARDS), contributing a novel addition to the medical literature. The co-occurrence of these conditions sheds light on a rare clinical scenario that requires careful consideration. PATIENT CONCERNS: The patient exhibited symptoms of pronounced dyspnea, tachypnea, and hypoxemia. Clinical assessment revealed irregular heart rhythms, notably atrial flutter, alongside characteristic signs of ARDS, including bilateral pulmonary infiltrates and reduced lung compliance. DIAGNOSES AND INTERVENTIONS: After a comprehensive evaluation, the patient was diagnosed with atrial flutter complicating ARDS. Therapeutic measures encompassed antiarrhythmic agents, mechanical ventilation, and targeted ARDS management protocols. The intricate interplay between cardiac and respiratory factors necessitated a multidisciplinary approach. OUTCOMES: Throughout treatment, the patient's respiratory distress gradually improved. Control of the atrial flutter was achieved, and oxygenation levels were restored within acceptable limits. This successful outcome underscores the significance of a well-coordinated treatment strategy in addressing complex cases like this. LESSONS: This case highlights the importance of recognizing and managing the intricate relationship between cardiac arrhythmias such as atrial flutter and respiratory complications like ARDS. The successful management of this patient underscores the value of multidisciplinary collaboration and tailored therapeutic interventions. Practitioners should remain vigilant for such rare complications and consider this case a reminder of the potential complexities that can arise in critical care scenarios.

Cardiovascular Disease: Atrial Fibrillation and Atrial Flutter.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in adults, with lifetime rates of 21% to 33%. There are numerous risk factors, including older age, hypertension, coronary disease, obstructive sleep apnea, diabetes, and others. Patients engaging in lifelong high-endurance exercise also have increased risk. Some organizations recommend screening; others do not. However, many patients identify AF themselves using mobile cardiac monitoring devices, some of which accurately detect the arrhythmia. Patients with AF with hemodynamic instability are treated with immediate synchronized cardioversion. Treatment options for stable patients include scheduled cardioversion, rhythm control with pharmacotherapy, catheter ablation, and rate control with pharmacotherapy. Catheter ablation is increasingly used as first-line therapy, with up to 80% of patients remaining AF-free after one or two ablation treatments, an outcome superior to that with pharmacotherapy. Patients with AF should receive anticoagulation based on the CHA2DS2-VASc (Congestive heart failure, Hypertension, Age 75 years or older [doubled], Diabetes, prior Stroke or transient ischemic attack or thromboembolism [doubled], Vascular disease, Age 65 to 74 years, Sex category) score, and also before and immediately after ablation or cardioversion. It is uncertain whether long-term anticoagulation is needed after successful ablation. Atrial flutter (AFL) is the second most common sustained supraventricular arrhythmia. Patients with AFL are at risk of developing AF, and many recommendations for managing AFL are similar to those for AF. The preferred management for AFL is catheter ablation, with success rates exceeding 90%.

Safety and Efficacy of Combining Left Atrial Appendage Occlusion With Another Cardiac Procedure.

BACKGROUND: Clinical outcomes of left atrial appendage occlusion (LAAO) combined with other cardiac procedures have not been previously examined. OBJECTIVES: This study sought to evaluate the safety and efficacy of combining LAAO with other cardiac procedures vs isolated LAAO. METHODS: We conducted a retrospective cohort study using the 2016 to 2020 National Inpatient Sample database to compare patients undergoing LAAO combined with another cardiac procedure vs isolated LAAO. Outcomes included risk-adjusted major adverse cardiovascular events (MACEs), in-hospital mortality, major complications, length of stay (LOS), and total costs. RESULTS: The total cohort included 88,910 weighted encounters, of which 1,225 (1.4%) involved concomitant cardiac procedures. After risk adjustment, patients in the concomitant procedure group had similar odds of MACEs (adjusted OR: 1.82; 95% CI: 0.94-2.74); in-hospital mortality; and complications including stroke, acute kidney injury, major bleeding, blood transfusion, and vascular injury. They also had similar LOS (1 day vs 1 day; P = 0.32) and higher costs ($44,723 vs $32,364; P < 0.01) compared with isolated LAAO but shorter LOS (1 day vs 2 days; P < 0.01) and lower costs ($51,552 vs $63,170; P = 0.04) compared with LAAO with sequential procedures. In subgroup analyses, concomitant atrial fibrillation/atrial flutter ablation had higher adjusted odds of heart block (P < 0.01), and concomitant transcatheter aortic valve replacement had higher adjusted odds of stroke (P = 0.02) and vascular injury (P < 0.01). CONCLUSIONS: In this retrospective observational study, combining LAAO with another cardiac intervention appeared to be associated with similar MACEs and LOS. However, certain complications appeared to be more frequent, and the cost was higher with combined procedures.

Dissecting the associations of KCNH2 genetic polymorphisms with various types of cardiac arrhythmias.

BACKGROUND: Cardiac arrhythmia, a common cardiovascular disease, is closely related to genetic polymorphisms. However, the associations between polymorphisms in KCNH2 and various arrhythmias remain inadequately explored. METHODS: Guided by the assumption that KCNH2 genetic polymorphisms significantly contribute to the development of arrhythmias, we thoroughly explored the associations between 85 KCNH2 genetic variations and 16 cardiac arrhythmias in a sample obtained from the UK Biobank (UKBB, N = 307,473). The illnesses documented in the electronic medical records of the sample were mapped to a phecode system for a more accurate representation of distinct phenotypes. Survival analysis was used to test the effect of KCNH2 variants on arrhythmia incidence, and a phenotype-wide association study (PheWAS) was performed to investigate the effect of KCNH2 polymorphisms on 102 traits, including physical measurements, biomarkers, and hematological indicators. RESULTS: Novel associations of variants rs2269001 and rs7789585 in KCNH2 with paroxysmal tachycardia (PT) and atrial fibrillation/flutter (AF/AFL), respectively, were identified. Moreover, with an increase in the number of minor alleles of these two variants, the incidence rates of PT and AF/AFL decreased. In addition, the PheWAS results suggested that these two single nucleotide polymorphisms were associated with multiple parameters in physical measurements and neutrophil percentage. CONCLUSION: The multiple novel associations observed in this study illustrate the importance of KCNH2 genetic variations in the pathogenesis of arrhythmia.

Association of sleep duration with atrial fibrillation/flutter mortality in the United States: a cross-sectional analysis.

BACKGROUND: The association between sleep duration and atrial fibrillation risk is poorly understood, with inconsistent findings reported by several studies. We sought to assess the association between long sleep duration and mortality due to atrial fibrillation/atrial flutter (AF/AFL). METHODS: The 2016-2020 Centers for Disease Control and Prevention (CDC) Wide-Ranging Online Data for Epidemiologic Research dataset was used to identify death records secondary to AF/AFL in the United States population. We used the 2018 Behavioral Risk Factor Surveillance System (BRFSS) dataset of sleep duration at the county level. All counties were grouped into quartiles based on the percentage of their population with long sleep duration (i.e., ≥ 7 h), Q1 being the lowest and Q4 the highest quartile. Age-adjusted mortality rates (AAMR) were calculated for each quartile. County Health Rankings for Texas were used to adjust the AAMR for comorbidities using linear regression. RESULTS: Overall, the AAMR for AF/AFL were highest in Q4 (65.9 [95% CI, 65.5-66.2] per 100,000 person-years) and lowest in Q1 (52.3 [95% CI, 52.1-52.5] per 100,000 person-years). The AAMR for AF/AFL increased stepwise from the lowest to highest quartiles of the percentage population with long sleep duration. After adjustment for the county health ranks of Texas, long sleep duration remained associated with a significantly higher AAMR (coefficient 220.6 (95% CI, 21.53-419.72, p-value = 0.03). CONCLUSIONS: Long sleep duration was associated with higher AF/AFL mortality. Increased focus on risk reduction for AF, public awareness about the importance of optimal sleep duration, and further research to elucidate a potential causal relationship between sleep duration and AF are warranted.

Focal pulsed field ablation and ultrahigh-density mapping - versatile tools for all atrial arrhythmias? Initial procedural experiences.

BACKGROUND: Focal pulsed field ablation (FPFA) is a novel and promising method of cardiac ablation. The aim of this study was to report the feasibility, short-term safety, and procedural findings for a broad spectrum of ablated atrial arrhythmias. METHODS: Patients (n = 51) scheduled for ablation of atrial arrhythmias were prospectively included and underwent FPFA using the Galvanize CENTAURI generator with energy delivery through commercially available ablation catheters with ultrahigh-density (UHDx) 3D electroanatomic voltage/local activation time map evaluations. Workflow, procedural data, and peri-procedural technical errors and complications are described. RESULTS: Planned ablation strategy was achieved with FPFA-only in 48/51 (94%) of the cases. Ablation strategy was first-time pulmonary vein isolation (PVI) in 17/51 (36%), repeat ablation in 18/51 (38%), PVI + in 13/51 (28%), and cavotricuspid isthmus block (CTI)-only in 3/51 (6%). The mean procedure time was 104 ± 31 min (first-time PVI), 114 ± 26 min (repeat procedure), 152 ± 36 min (PVI +), and 62 ± 17 min (CTI). Mean UHDx mapping time to assess lesion formation and block after ablation was 7 ± 4 min with 5485 ± 4809 points. First pass acute (linear) isolation with bidirectional block for anatomical lesion sets was 120/124 (97%) for all PVs, 17/17 (100%) for (any) isthmus, and 14/17 (82%) for left atrium posterior wall (LAPW). We observed several time-consuming integration errors with the used ablation system (mean 3.4 ± 3.7 errors/procedure), one transient inferior ST elevation when ablating CTI resolved by intravenous nitroglycerine and one transient AV block requiring temporary pacing for > 24 h. CONCLUSIONS: FPFA was a highly versatile method to treat atrial arrhythmias with high first-pass efficiency. UHDx revealed acute homogenous low-voltage lesions in ablated areas. More data is needed to establish lesion durability and limitations of FPFA.