European survey on efficacy and safety of duty-cycled radiofrequency ablation for atrial fibrillation

AIMS

Duty-cycled radiofrequency ablation (RFA) has been used for atrial fibrillation (AF) for around 5 years, but large-scale data are scarce. The purpose of this survey was to report the outcome of the technique.

METHODS AND RESULTS

A survey was conducted among 20 centres from seven European countries including 2748 patients (2128 with paroxysmal and 620 with persistent AF). In paroxysmal AF an overall success rate of 82% [median 80%, interquartile range (IQR) 74-90%], a first procedure success rate of 72% [median 74% (IQR 59-83%)], and a success of antiarrhythmic medication of 59% [median 60% (IQR 39-72%)] was reported. In persistent AF, success rates were significantly lower with 70% [median 74% (IQR 60-92%)]; P = 0.05) as well as the first procedure success rate of 58% [median 55% (IQR 47-81%)]; P = 0.001). The overall success rate was similar among higher and lower volume centres and were not dependent on the duration of experience with duty-cycled RFA (r = -0.08, P = 0.72). Complications were observed in 108 (3.9%) patients, including 31 (1.1%) with symptomatic transient ischaemic attack or stroke, which had the same incidence in paroxysmal and persistent AF (1.1 vs. 1.1%) and was unrelated to the case load (r = 0.24, P = 0.15), bridging anticoagulation to low molecular heparin, routine administration of heparin over the long sheath, whether a transoesophageal echocardiogram was performed in every patient or not and average procedure times.

CONCLUSION

Duty-cycled RFA has a self-reported success and complication rate similar to conventional RFA. After technical modifications a prospective registry with controlled data monitoring should be conducted to assess outcome.

Radiofrequency catheter ablation of two right Mahaïm-like accessory pathways in a patient with Ebstein's anomaly

A 17-year-old woman with Ebstein's anomaly and recurrent episodes of antidromic tachycardia with two distinct morphologies is described. The tachycardias were produced by two separate Mahaïm-like accessory pathways. These were localized by their activation potentials at the anterolateral ventricular margin of the tricuspid annulus and ablated in a single session using radiofrequency current.

Pattern of coronary artery disease in patients with ventricular tachycardia and fibrillation exposed by exercise-induced ischemia

The majority of patients with serious exercise-induced ventricular arrhythmias have extensive coronary artery disease. These arrhythmias develop, however, only in a minority of patients with angina pectoris. The purpose of the present study was therefore to investigate whether these arrhythmia patients are characterized by any specific "arrhythmogenic" pattern of coronary artery disease. Among 1100 consecutive patients undergoing coronary artery bypass grafting, 30 (2.7%) patients had ventricular tachycardia or fibrillation during preoperative exercise testing. For each of these patients, two matched controls with angina pectoris but no ventricular arrhythmia were selected. All patients underwent angiocardiography by standard techniques. The recordings were blinded and interpreted in random order by an experienced invasive cardiologist. Significant stenosis (> or = 50%) of the main left coronary artery was found in 27% of the case patients compared to 12% of the matched controls (p = 0.069, two-tailed t test); proximal left anterior descending artery stenoses were more frequent in the arrhythmia patients. Although stenosis > or = 75% was only moderately more frequent in the case patients, the difference was highly significant for stenosis > or = 95%, which was seen in 47% of the case patients compared to 22% of the controls (p = 0.015). The difference was even more pronounced for the combination of main left coronary artery stenosis and/or high-grade stenosis (> or = 95%) of the left anterior descending artery. This pattern was seen in 60% of the case patients compared to 28% of the matched controls (p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

QRS prolongation as an indicator of risk of ischemia-related ventricular tachycardia and fibrillation induced by exercise

The majority of patients with serious ventricular arrhythmias induced by exercise have ischemic heart disease. These arrhythmias, however, develop only in a minority of the patients with coronary artery disease. The aim of this study was to investigate whether patients with ventricular tachycardia or fibrillation produced by exercise-induced ischemia exhibit any premonitory electrocardiographic indicators of arrhythmia propensity and whether arrhythmia suppression by myocardial revascularization abolished these changes. High-quality exercise electrocardiograms (50 mm/sec) from 30 case patients with ventricular tachycardia and fibrillation produced by exercise-induced ischemia were studied before and after surgical revascularization. These results were compared with those obtained from 30 control patients matched for age, sex, heart disease, and preoperative exercise capacity. The resting and peak exercise electrocardiograms were examined separately in a blinded manner with respect to QRS duration, ST-segment depression, and JT intervals. Patients with bundle branch block patterns were excluded. The QRS duration at rest was similar in case and control patients preoperatively and increased significantly with exercise in both groups. However, the QRS prolongation was larger in the case group, in which it was 11 +/- 3 msec compared with 4 +/- 2 msec in the control group (p = 0.043). QRS prolongation > or = 15 msec predicted ischemia-related ventricular arrhythmias in 73% of the patients. After surgical revascularization, there was no QRS prolongation with exercise in either group. In both groups, the QRS prolongation was associated with significant ST-segment depression, which was larger in the case patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical revascularization in the treatment of ventricular tachycardia and fibrillation exposed by exercise-induced ischaemia

The role of myocardial revascularization in the treatment of malignant ventricular arrhythmias is not well defined. Our hypothesis was that in patients with ventricular tachycardia or fibrillation exposed by exercise-induced ischaemia, the acute transient ischaemia plays a principal causal role, and that in these patients surgical myocardial revascularization alone might be an effective treatment. Among 1100 consecutive patients undergoing isolated coronary artery bypass surgery (CABG) 30 patients (2.7%) characterized by ventricular tachycardia or fibrillation at the symptom-limited exercise tests prior to revascularization were studied prospectively. All patients had exercise-induced angina pectoris or ischaemic ST-segment depression preceding at least one of the arrhythmic events. In addition, eight of these 30 patients had experienced syncope during out-of-hospital exertional activities. After surgical revascularization, the 28 patients surviving to hospital discharge were followed for 1.6 to 86 months (mean 29 +/- 29 months) as outpatients and underwent between one to eight exercise tests (mean 2.6 +/- 1.9). One of these patients died suddenly of unknown causes at 14 months, another from cancer at 53 months. Twenty-six patients experienced a total of 34 episodes of ventricular tachycardia before revascularization. Two of these patients, both having residual ischaemia, had arrhythmia recurrences during follow-up; odds ratio (OR) 84.5, 95% confidence interval (CI) 18.7-381.9; P = < 0.010. Exercise-induced ventricular fibrillation occurred in eight patients pre-operatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Lidocaine to prevent ventricular fibrillation in the prehospital phase of suspected acute myocardial infarction: the North-Norwegian Lidocaine Intervention Trial

The efficacy of lidocaine to prevent ventricular fibrillation during the prehospital phase of suspected acute myocardial infarction was assessed 3 hours after administration in a randomized controlled trial. A total of 204 patients examined within 6 hours after onset of symptoms were included, and acute myocardial infarction was later confirmed in 63% of these. Lidocaine, administered as a 100 mg intravenous bolus dose followed by a 300 mg intramuscular injection, failed to prevent ventricular fibrillation, which was observed in 2 (2.1%) of 96 patients in the lidocaine group and in 3 (3.0%) of 101 patients in the placebo group (p = 0.95; odds ratio 0.7, 95% confidence interval 0.4 to 1.3). In addition, sudden cardiac collapse with unknown heart rhythm was observed in three patients who received lidocaine (3.1%) compared with none in the placebo group (p = 0.23; odds ratio 7.6, 95% confidence interval 2.8 to 22.1). The results of this small study suggest that lidocaine, even when given in a high dose, is ineffective in preventing ventricular fibrillation when administered before hospitalization for suspected acute myocardial infarction. Prophylactic use of lidocaine in this situation may therefore not be warranted or advisable.

Therapeutic lidocaine concentrations have no effect on blood platelet function and plasma catecholamine levels

The effects of therapeutic plasma concentrations of lidocaine on blood platelet function and plasma catecholamine levels were assessed in 9 healthy subjects. There were no significant effects on plasma levels of beta-thromboglobulin, collagen and adenosine diphosphate-stimulated platelet aggregation, thromboxane-B2-concentration in plasma after collagen and ADP stimulated platelet aggregation, or on plasma nor-adrenaline and adrenaline. No significant correlation could be demonstrated between any of the variables tested. Thus, it appeared that lidocaine had no effect on platelets that could be of benefit in acute myocardial infarction. It should be possible to use lidocaine, in combination with thrombolytic therapies without increasing the risk of bleeding complications.

Monitoring a randomized clinical trial for futility: the north-Norwegian lidocaine intervention trial

Randomized clinical trials of acute disease are usually designed as single-look, fixed sample size trials. This methodological study compares the conventional approach with a multiple-look, group sequential design with stopping rules for both treatment efficacy and for an inconclusive trial outcome, called trial futility. An ongoing trial on pre-hospital prophylaxis of sudden death in acute myocardial infarction forms the basis of the analysis. The effects of introducing multiple looks (or interim analyses) and tests for futility were obtained by binomial simulation. The introduction of four looks (that is, three interim and a final analysis) resulted in a modest increase in the maximal number of patients required. This was, however, fully compensated for by the high probability of early termination in case of treatment efficacy. The addition of futility tests, enabling termination at half the maximum trial size when there is no treatment difference, resulted in only a negligible reduction of overall power. We conclude that multiple-look, group sequential designs testing for both treatment efficacy and trial futility may improve the cost-effectiveness of randomized trials of acute disease.