Cryoablation as standard treatment of atrial flutter: a prospective, 2-center study (CASTAF).

BACKGROUND: Cryoablation (CRYO) of cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) has been shown to be non-inferior to radiofrequency ablation (RF) in terms of ablation success and is associated with less pain. However, procedural time has been significantly longer with CRYO compared to RF. A possible explanation for this could be that operators had less experience with CRYO than with RF. The purpose of this study was to test the hypothesis that in the hands of experienced operators, cryoablation of CTI-dependent AFL is effective with procedure-time similar to what is reported for RF. METHODS: This prospective 2-center study included 184 patients with CTI-dependent AFL - median age 66 years (range 28-83), 159 men (86%). Cryoablation was performed using a 9 F, 8 mm tip catheter (Freezor MAX, Medtronic, Inc, MN, USA). Ablation endpoint was bidirectional CTI-block. Pain was evaluated with a visual analogue scale (VAS 0-10). All operators had experience of at least 25 previous CTI-ablations with CRYO. RESULTS: The acute success rate was 89%. Procedural time including an observation period of 30 min, was 115 ± 36 min which is similar to procedural times for RF in previous studies. Fluoroscopy time was 11 ± 9 min. Cryoablation was perceived as almost pain- free by the patients, VAS (mean) 1.8 ± 1.2. Success rate at 12-month follow-up (FU) was 88% in patients with primary success. No major adverse events occurred. CONCLUSIONS: Cryoablation of CTI-dependent AFL is effective, with a low level of procedure-related pain. In experienced hands, the procedure time in this prospective non-randomised trial seems to be in the level of reported procedure times for RF. The long-term relapse rate appears to be higher than for RF.

Sinus node recovery time assessment revisited: role of pharmacologic blockade of the autonomic nervous system.

Sinus node recovery time assessment is used to diagnose clinically significant sinus node dysfunction (SND) when Holter has failed to prove a relationship between sinus bradyarrhythmias and symptoms, but consensus has not been reached as to the value of including assessment after pharmacologic blockade of the autonomic nervous system. This issue was addressed in the present study performed on 52 patients with syncope or presyncope/dizziness (n = 48), sinus bradyarrhythmias (n = 45), or both (n = 41). Group 1 consisted of 13 patients with a proven relationship between symptoms and sinus bradyarrhythmias. Group 2 consisted of 39 patients with suspected SND. The protocol included three pacing periods at two pacing rates and was performed at baseline (n = 52), after single doses of atropine and propranolol (0.02 mg/kg and 0.1 mg/kg, respectively) (n = 41), and again after a second dose (n = 29). The sensitivity of prolonged recovery times was 77% in group 1. Among group 2 patients, 56% had prolonged recovery times at baseline (79% when including the results after the first dose of drugs). The second dose did not contribute diagnostic information, but it caused significant adverse reactions in 7 of 29 patients (P < 0.001). These 7 patients were all older than 60 years. Assessment of sinus node recovery time after pharmacologic blockade of the autonomic nervous system thus increases the sensitivity of the method in patients with suspected SND and normal baseline results. However, only 50% of the initially suggested doses of atropine and propranolol is sufficient and eliminates the risk for significant adverse reactions.

Selective Ik blocker almokalant exhibits class III--specific effects on the repolarization and refractoriness of the human heart: a study of healthy volunteers using right ventricular monophasic action potential recordings.

Almokalant, a recently developed potassium-channel blocker, has exhibited properties of a selective class III agent in vitro and in animal experiments. We report the first invasive study in humans in which the electrophysiological characteristics of almokalant were assessed. Thirty-four healthy males received bolus and maintenance infusions of almokalant to two of our target plasma concentrations of 20, 50, 100, and 150 nM. Electrophysiological variables were assessed during stimulation at 100 and 120 beats/min at baseline and at two consecutive targeted levels. Almokalant dose-dependently increased the duration of the monophasic action potential (MAP) above a mean plasma concentration of 60 nM. The duration at 90% repolarization significantly increased by 20% from baseline at 100 beats/min (p < 0.00005), and by 19% at 120 beats/min (p < 0.00005), at a mean plasma concentration of 116 nM. During atrial stimulation, there was a significant increase in the QT interval, amounting to 24% at 100 beats/min (p < 0.00005) and to 30% at 120 beats/min (p = 0.0006), at 124 nM. During right ventricular stimulation in the apical region, the QT interval significantly increased by 17% at 100 beats/min (p < 0.00005), and 13% at 120 beats/min (p < 0.00005). During stimulation from the right ventricular outflow tract, the QT interval increased to a lesser extent and significantly only at 120 beats/min: 9% at 100 beats/min (p = NS) and 6% at 120 beats/min (p = 0.001) at 118 nM. The effective refractory period (ERP) of the atria increased by 18% at 100 beats/min at 119 nM (p = 0.005). The right ventricular ERP increased by 16% at both heart rates (HR) (p < 0.00005) during stimulation from the apical region, and by 11% during stimulation from the outflow tract (p = 0.0001 at 100 beats/min and p = 0.0006 at 120 beats/min). There was no effect on the ERP of the atrioventricular node, (AVN) on the sinus node function or cardiac conduction. Two individuals experienced a transient metallic taste during bolus infusion aiming at 50 and 100 nM, but this side effect did not occur in the group receiving the highest doses. Pronounced T-wave/U-wave (TU) morphology changes were observed in 4 individuals. Almokalant exhibited characteristics of a pure class III agent with no effects on cardiac conduction or sinus node function when given intravenously. Although no proarrhythmias were observed, the development of TU morphology changes and increased spatial dispersion of repolarization after the highest doses warrants further studies regarding the safety profile of the drug.

HLA-B27: an important genetic risk factor for lone aortic regurgitation and severe conduction system abnormalities.

PURPOSE: HLA-B27, an immunogenetic marker that is present in 8 percent of the white population around the world, has been found to be an important risk factor for the development of a group of rheumatic disorders, the seronegative spondyloarthropathies. Our objective was to assess the possible role of HLA-B27 and the associated inflammatory disease process in the development of lone aortic regurgitation. PATIENTS AND METHODS: A group of 91 patients with lone aortic regurgitation were studied by HLA typing and clinical and roentgenologic examination. RESULTS: The HLA-B27-associated inflammatory disease process was found to be the probable underlying cause in 15 to 20 percent of patients with lone aortic regurgitation of different degrees of severity. Furthermore, HLA-B27 was found in 88 percent of the male patients with the combination of aortic regurgitation and severe conduction system abnormalities. CONCLUSION: We suggest that this cardiac syndrome should be regarded as an HLA-B27-associated syndrome, sometimes part of ankylosing spondylitis or Reiter's disease, but just as often presenting without obvious rheumatic disease. The marker is thus an important and widely distributed risk factor not only for the development of rheumatic disease but also for acquired aortic regurgitation and sever conduction system abnormalities.