Cryoballoon versus radiofrequency catheter ablation for paroxysmal atrial fibrillation.

BACKGROUND: Catheter ablation is an established treatment for atrial fibrillation (AF). Cryoballoon ablation (CBA) has emerged as an alternative to radiofrequency ablation (RFA). However, there are few data comparing these modalities for treatment of paroxysmal AF (pAF) in the U.S. POPULATION: The purpose of this study was to compare procedural times, safety, and efficacy of CBA against RFA. METHODS: A single-center prospective cohort study evaluated patients who underwent catheter ablation for pAF using CBA or RFA between January 1, 2010 and October 31, 2013. Patients with prior ablation and those without rhythm follow-up for at least 3 months were excluded. The primary end point was freedom from AF, atrial flutter, and atrial tachycardia (FFAF) >30 seconds after a 3-month blanking period without requirement for antiarrhythmic drugs. We also compared rates of successful pulmonary vein isolation (PVI), fluoroscopy and procedure times, and major complication rates. RESULTS: A total of 201 patients were included (CBA = 101, RFA = 100). The rate of successful PVI was 99.3% in CBA versus 97.4% in RFA (P = 0.08). Procedure times were shorter with CBA (192.9 ± 44.0 minutes vs 283.7 ± 78.0 minutes, P < 0.001) as well as total fluoroscopy times (46.0 ± 22.4 minutes vs 73.0 ± 30.1 minutes, P < 0.001). Overall complication rates were equivalent; however, fewer cardiac perforations occurred with CBA (0% vs 4%, P = 0.042). The 1-year FFAF rates were 60.3% for CBA and 61.1% for RFA (log rank P = 0.93). CONCLUSION: CBA was associated with equivalent 1-year FFAF rate as RFA for pAF. Procedure and fluoroscopy times were shorter for CBA and fewer cardiac perforations occurred.

The subcutaneous implantable cardioverter and defibrillator: advantages, limitations and future directions.

The totally subcutaneous implantable cardioverter and defibrillator (S-ICD) represents the most innovative development in implantable cardioverter and defibrillator therapy in the last 15 years. Its development arose out of concern for the long-term complications of transvenous devices. Clinical trials have shown that it is a safe and effective device for patients at risk of sudden cardiac death. The lack of transvenous and intracardiac components makes it an attractive choice for young patients, those with limited vascular access and increased infectious risk. Despite these advantages, the current S-ICD system has limitations, including the inability to deliver cardiac pacing. Future programming and technologic advancements have the opportunity to dramatically improve the efficacy and broaden the patient population treated with the S-ICD.

The totally subcutaneous implantable defibrillator.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is a new therapeutic option for patients at risk of sudden cardiac arrest. The device uses a pulse generator implanted in the lateral thoracic region and a tunneled subcutaneous electrode. Benefits of this configuration include the preservation of venous access and reduction in the risk of systemic infection, vascular injury, and lead failure. Clinical trials suggest that the device effectively senses, discriminates, and converts both spontaneous and induced ventricular tachycardia and ventricular fibrillation episodes with minimal complications. The S-ICD represents a novel implantable cardioverter-defibrillator configuration that may provide reliably effective therapy for malignant tachyarrhythmias.

Use of an electrocardiographic screening tool to determine candidacy for a subcutaneous implantable cardioverter-defibrillator.

BACKGROUND: An electrocardiographic (ECG) screening test has been developed to identify patients being considered for a totally subcutaneous implantable cardioverter-defibrillator (S-ICD) at risk for T-wave oversensing. OBJECTIVE: The purpose of this study was to determine the proportion of potential S-ICD recipients who fail the ECG screening test and to identify predictors of failure. METHODS: Patients who already have an ICD but are not receiving antibradycardia pacing are representative of patients who might be considered for an S-ICD. One hundred such outpatients were enrolled in the study. Surface rhythm strips were recorded along the sensing vectors of the S-ICD system and the screening template applied. Clinical and standard ECG characteristics of patients who failed the test were compared to those who passed. RESULTS: Patients had the following characteristics: 72% male, age 57 ± 16 years, body mass index 29 ± 6 kg/m(2), left ventricular ejection fraction 43% ± 17%, QRS duration 109 ± 23 ms, QTc interval 447 ± 39 ms, 44% had coronary disease, and 55% had heart failure. Among the 100 patients, 8% failed the screening test. There were no differences in patient clinical characteristics and most standard ECG measurements. However, patients with T-wave inversions in standard ECG leads I, II, and aVF had a 45% chance of failing. CONCLUSION: Eight percent of potential S-ICD patients were not eligible for the S-ICD after failing the screening test designed to identify patients susceptible to T-wave oversensing. Patients with T-wave inversions in leads I, II, and aVF on a standard ECG were 23 times more likely to fail. More work is needed in S-ICD sensing algorithms to increase patient eligibility for the S-ICD.