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Objectives This study sought to evaluate the safety and effectiveness of catheter ablation of persistent atrial fibrillation (PsAF) using a porous tip contact force–sensing catheter. Backg...

Purpose The prospective, multicenter SMART SF trial demonstrated the acute safety and effectiveness of the 56-hole porous tip irrigated contact force (CF) catheter for drug-refractory paroxysmal atrial fibrillation (PAF) ablation with a low primary adverse event rate (2.5%), leading to FDA approval of the catheter. Here, we are reporting the long-term effectiveness and safety results that have not yet been reported. Methods Ablations were performed using the 56-hole porous tip irrigated CF catheter guided by the 3D mapping system stability module. The primary effectiveness endpoint was freedom from atrial tachyarrhythmia (including atrial fibrillation, atrial tachycardia, and/or atrial flutter), based on electrocardiographic data at 12 months. Atrial tachyarrhythmia recurrence occurring 3 months post procedure, acute procedural failures such as lack of entrance block confirmation of all PVs, and undergoing repeat procedure for atrial fibrillation in the evaluation period (91 to 365 days post the initial ablation procedure) were considered to be effectiveness failures. Results Seventy-eight patients (age 64.8 ± 9.7 years; male 52.6%; Caucasian 96.2%) participated in the 12-month effectiveness evaluation. Mean follow-up time was 373.5 ± 45.4 days. The Kaplan-Meier estimate of freedom from 12-month atrial tachyarrhythmia was 74.9%. Two procedure-related pericardial effusion events were reported at 92 and 180 days post procedure. There were no pulmonary vein stenosis complications or deaths reported through the 12-month follow-up period. Conclusions The SMART SF 12-month follow-up evaluation corroborates the early safety and effectiveness success previously reported for PAF ablation with STSF.

Background: There is limited evidence on the long-term clinical benefits of catheter ablation in patients with persistent atrial fibrillation. Methods: PRECEPT was a prospective, multicenter, single-arm Food and Drug Administration–regulated investigational device exemption clinical study. Patients were followed up to 15 months after ablation. Outcomes included use of antiarrhythmic drugs, rate of cardioversions and cardiovascular hospitalization, Atrial Fibrillation Effect on Quality-of-Life score, and Canadian Cardiovascular Society Severity of Atrial Fibrillation score. Results: A total of 333 enrolled persistent atrial fibrillation patients underwent ablation. The cardioversion rate decreased by 83% at the 9- to 15-month follow-up. Antiarrhythmic drug utilization decreased by 69% at 12 to 15 months post-ablation. The Kaplan-Meier estimate of freedom from cardiovascular hospitalization was 84.2% (95% CI, 80.2%–88.2%) at 15 months. Consistent improvements in mean Atrial Fibrillation Effect on Quality-of-Life composite (+50.0) were seen at 6 months, sustained at 15 months, and exceeded the minimum clinically important difference. Improvements in Atrial Fibrillation Effect on Quality-of-Life scores were significantly better among participants without documented atrial arrhythmia recurrences. By Canadian Cardiovascular Society Severity of Atrial Fibrillation symptom classification, >80% of patients were asymptomatic (class 0) at 15 months post-ablation compared with only 0.7% at baseline. Conclusions: Contact force–guided radiofrequency ablation of persistent atrial fibrillation was associated with a significant decrease in antiarrhythmic drug use, cardioversion rate, and hospitalization. Clinically meaningful improvements in quality of life were observed in all patients. The majority of the patients (>80%) were asymptomatic at 15 months post-ablation. The positive clinical impact of improved quality of life and reduced health care utilization may help with shared decision-making in persistent atrial fibrillation treatment. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02817776.

Aims THERMOCOOL SMARTTOUCH® SF Catheter is a new contact-force (CF)-sensing catheter with 56-hole porous tip designed for improved cooling and reduced fluid delivery compared with a standard 6-hole open-irrigated catheter. The SMART SF study examined the periprocedural safety, acute effectiveness, and procedural efficiency of the catheter for drug-refractory symptomatic paroxysmal atrial fibrillation (PAF) ablation. Methods and results The prospective, open-label, non-randomized SMART-SF was conducted at 17 US sites. Circumferential pulmonary vein (PV) isolation was performed with confirmation of entrance block in all PVs. Stable ablation sites were identified using CARTO VISITAG™ Module. Primary adverse events (AEs; ≤1 week of index procedure), periprocedural AEs within 30 days of ablation procedure, acute effectiveness (confirmation of entrance block for targeted PVs), CF, and procedural parameters were assessed. Overall, 165 patients were enrolled (mean age, 62.7 years; male, 57.9%; white, 97%; left ventricular ejection fraction, 60.1 ± 7%; left atrium diameter, 38.8 ± 6 mm); 159 underwent radiofrequency ablation and comprised the safety cohort. Primary safety performance criteria were met: primary AE rate was 2.5% (4/159; cardiac tamponade [n = 2], thrombo-embolism [n = 1], transient ischaemic attack [n = 1]). All primary AEs resolved/improved within the 1-month follow-up period. Acute procedural effectiveness was attained in 96.2% (95% confidence interval: 92.0-98.6%) of patients. Procedure time, fluoroscopy time, and fluid delivered were observed in comparison to predecessor catheters. Conclusion In the SMART-SF trial, the predetermined safety performance goal was met, demonstrating the safety and acute effectiveness of the THERMOCOOL SMARTTOUCH® SF Catheter for PAF ablation.

In the present study we determined the long-term effects of persistent, local insulin-like growth factor I (IGF-I) expression on cardiac function in the SIS2 transgenic mouse. Cardiac mass/tibial length was increased in SIS2 mice by 10 wk of age; this cardiac hypertrophy became more pronounced later in life. Peak aortic outflow velocity, a correlate of cardiac output, was increased at 10 wk in SIS2 mice but was decreased at 52 wk. 72 wk SIS2 mouse hearts exhibited wide variability in the extent of cardiac hypertrophy and enlargement of individual cardiac myofibers. Sirius red staining revealed increased fibrosis in 72 wk SIS2 hearts. Persistent local IGF-I expression is sufficient to initially induce an analog of physiological cardiac hypertrophy in which peak aortic outflow velocity is increased relative to controls in the absence of any observed detrimental histological changes. However, this hypertrophy progresses to a pathological condition characterized by decreased systolic performance and increased fibrosis. Our results confirm the short-term systolic performance benefit of increased IGF-I, but our demonstration that IGF-I ultimately diminishes systolic performance raises doubt about the therapeutic value of chronic IGF-I administration. Considering these findings, limiting temporal exposure to IGF-I seems the most likely means of delivering IGF-I's potential benefits while avoiding its deleterious side effects.

Adult transgenic mice with muscle-specific overexpression of insulin-like growth factor (IGF)-I have enlarged skeletal muscles. In this study, we; 1) characterized the development of muscle hypertrophy with respect to fiber type, age, and sex; 2) determined the primary anabolic process responsible for development of hypertrophy; and 3) identified secondary effects of muscle hypertrophy on body composition. Transgene expression increased with age and was present only in fibers expressing type IIB fast myosin heavy chain. Muscle masses were greater by 5 wk of age, and by 10 wk of age the differences were maximal despite continued transgene expression. Total DNA and RNA contents of the gastrocnemius muscle were greater for transgenic mice than for nontransgenic littermates. The differences were maximal by 5 wk of age and preceded the increase in protein mass. The accelerated protein deposition ceased when the protein/DNA ratio attained the same value as in nontransgenic controls. Despite localization of IGF-I expression to muscle without changes in plasma IGF-I concentrations, genotype also modified the normal age and sex effects on fat deposition and organ growth. Thus, enhanced DNA accretion by IGF-I was primarily responsible for stimulating muscle growth. In turn, secondary effects on body composition were incurred that likely reflect the impact of muscle mass on whole body metabolism.