Sensitivity and specificity of programmed atrial stimulation for induction of supraventricular tachycardias

Atrial tachycardia occurring after a prior atrial fibrillation ablation procedure: Does non-inducibility matter?

Recurrent atrial tachycardia (AT) is a common phenomenon after catheter ablation for AF, particularly in the setting of additional substrate ablation, with many studies demonstrating gap-related macro re-entrant AT (predominantly mitral and roof dependent) to be the dominant mechanism. Although multiple inducible ATs after ablation of the clinical AT are commonly described at repeat procedures, the optimal ablation strategy, and procedural endpoints are unclear in this setting. A recent randomized study addressing the question of non-inducibility as a procedural endpoint demonstrated no additional benefits to the ablation of all induced, non-clinical ATs, but it was limited by small numbers and high rates of non-inducibility. Nevertheless, once ablation of the clinical AT has been successfully performed, ensuring durable linear block and PV isolation may be sufficient for the prevention of further AT. Durable linear block, particularly at the mitral isthmus, is difficult to achieve but may be facilitated by the real-time evaluation of lesion quality and contiguity and the novel technique of vein of Marshall ethanol infusion. Large-scale, randomized trials are needed, nonetheless, to fully assess the optimal ablation strategy in the setting of recurrent AT post-AF ablation.

Implantable loop recorders detect tachyarrhythmias in symptomatic patients with negative electrophysiological studies

BACKGROUND

Implantable loop recorders (ILR) are a valuable tool in the investigation of syncope and compare favourably with non-invasive and intracardiac electrophysiological assessment of bradycardia. They are known to detect tachyarrhythmias but have not been shown to add to the diagnostic yield of electrophysiological testing in symptomatic patients.

METHODS

We prospectively studied the first 41 patients (aged 48+/-19 years) in whom ILR were used at our institution after negative electrophysiological studies (EPS). All patients were symptomatic with palpitations (11), syncope (22) or both (8). Nine patients had known structural heart disease (two ischaemic, four cardiomyopathy, two valvular and one congenital). Patients were assessed according to demographic factors, symptoms and investigations. Loop recordings were analysed and assessed according to conventional criteria.

RESULTS

Among 41 patients in whom electrophysiological studies had failed to demonstrate arrhythmias, six were found to have clinically significant tachyarrhythmias (four ventricular and two supraventricular).

CONCLUSION

ILR diagnose prognostically significant tachyarrhythmias in symptomatic patients with negative electrophysiological studies.

Induction of atrial fibrillation with rapid high voltage ventricular pacing for ventricular fibrillation conversion testing. The Ventak AV II DR Study

OBJECTIVE

To assess whether rapid high voltage ventricular pacing can also induce atrial fibrillation, and whether the induction of atrial fibrillation during ventricular fibrillation conversion testing is related to the patient's heart disease.

DESIGN

Prospective study of 50 patients who received the dual chamber implantable cardioverter-defibrillator (ICD) Ventak AV II DR (Guidant) as a first implant. This device can record atrial activity even during a ventricular fibrillation episode and can induce atrial fibrillation by rapid atrial bursts.

MAIN OUTCOME MEASURES

Frequency of atrial fibrillation after induction of ventricular fibrillation; clinical characteristics of patients with and without induced atrial fibrillation; frequency of atrial fibrillation induced by rapid atrial bursts during predischarge testing.

RESULTS

Atrial fibrillation was observed in 40 of the 217 ventricular fibrillation episodes (18%) that could be detected immediately after delivery of high voltage pacing. The biphasic ICD shock for termination of ventricular fibrillation also terminated the atrial fibrillation in all cases. The 40 episodes of simultaneous atrial and ventricular fibrillation occurred in 18 patients (36%). The distribution of the clinical characteristics of the patients and the inducibility of atrial fibrillation during predischarge testing were similar in those with and without induced atrial fibrillation.

CONCLUSIONS

Rapid high voltage ventricular pacing frequently induces atrial fibrillation, which was terminated by the subsequent biphasic ICD shock. The induction of atrial fibrillation seems to be a non-specific phenomenon, unrelated to the clinical status of the patient.

Effects of coronary artery bypass grafting on ventricular arrhythmias: results with electrophysiological testing and long-term follow-up

Myocardial revascularization was performed in 56 patients with coronary artery disease who presented with ventricular tachycardia (VT) (n = 39) or ventricular fibrillation (n = 17). There were 46 men and 10 women, aged 65 +/- 10 years. Three vessel (n = 42) or left main disease (n = 4) was present in 82%. Left ventricular ejection fraction averaged 36% +/- 11%. Electrophysiological studies were performed preoperatively in all patients; 50 (89%) had inducible ventricular arrhythmias. Sustained monomorphic VT was induced in 40 patients (cycle length 284 +/- 61 msec). Reproducible symptomatic nonsustained VT was induced in four patients and ventricular fibrillation in six patients, while six patients had no inducible arrhythmia. Preoperatively the patients with inducible VT failed 3.3 +/- 1.2 drug trials during electrophysiological studies. In addition to coronary bypass, 22 patients also received an automatic implantable cardioverter defibrillator (ICD), 26 patients received prophylactic ICD patches, and 1 patient had resection of a false aneurysm. There were no perioperative deaths. Postoperative electrophysiological studies were performed in all 56 surgical survivors. Ventricular tachyarrhythmia could not be induced in the six patients who had no inducible VT preoperatively and in 13 of 40 (33%) with preoperatively inducible sustained VT or in 19 of 50 (38%) patients with any previously inducible ventricular arrhythmia, thus a total of 25 patients (45%) had no inducible VT postoperatively. Of the remaining, 11 patients were treated with antiarrhythmic drugs alone, 11 had already received an ICD (combined with drugs in 7), and another 9 received the ICD postoperatively (combined with drugs in 4).(ABSTRACT TRUNCATED AT 250 WORDS)

Value of programmed ventricular stimulation in the evaluation and management of patients with nonsustained ventricular tachycardia associated with coronary artery disease

Programmed ventricular stimulation with up to 3 extrastimuli at the right ventricular apex was performed in 52 patients with spontaneous nonsustained ventricular tachycardia (VT) associated with coronary artery disease. There were 44 men and 8 women, aged 66 +/- 9 years (range 45 to 86). The mean left ventricular ejection fraction was 41 +/- 14%. Nonsustained VT was asymptomatic in 10 patients (19%), while the arrhythmia was detected during evaluation of palpitations in 5 patients (10%), presyncope in 11 (21%) and syncope in 26 patients (50%). All patients were tested in the drug-free state and were classified as having no inducible arrhythmia (31 patients, group I), or an inducible arrhythmia (21 patients, group II). The age, gender, type of heart disease, symptoms and left ventricular ejection fraction were similar in both groups. Group I patients had a higher overall incidence of syncope. Group I patients received no therapy, while group II patients received antiarrhythmic therapy guided by electropharmacologic testing. At 21 +/- 17 months there was no sustained VT in either group. There were 3 deaths in group I patients, including 1 sudden, 1 nonsudden cardiac and 1 noncardiac death. In group II patients 6 deaths occurred including 4 nonsudden cardiac and 2 noncardiac deaths. In patients with nonsustained VT and coronary artery disease undergoing programmed ventricular stimulation, the incidence of significant arrhythmic events is low in those without therapy with no inducible arrhythmia, and in those with an inducible arrhythmia with therapy guided by electrophysiologic testing.

Reversal of electrophysiologic effects of flecainide on the accessory pathway by isoproterenol in the Wolff-Parkinson-White syndrome

To determine the reversibility of the effects of flecainide on accessory pathways, electrophysiologic studies were performed in the drug-free control state, after flecainide loading and with isoproterenol infusion during flecainide treatment in 12 patients with symptomatic preexcitation syndrome. After the baseline drug-free evaluation, oral flecainide was given in dosages of 50 to 200 mg twice daily (mean daily dose 282 +/- 75) for at least 4 days before the repeat electrophysiologic study. Isoproterenol infusion was given in dosages of 1 to 4 micrograms/min to increase the heart rate at rest by 50%. Anterograde block in the accessory pathway was observed in 3 patients with flecainide therapy, whereas in the other patients the anterograde refractory period increased from 243 +/- 20 to 315 +/- 23 ms (p less than 0.05). The shortest preexcited RR interval during atrial fibrillation lengthened from 234 +/- 27 ms before flecainide to 313 +/- 38 ms (p less than 0.05). Retrograde block occurred in 2 patients after flecainide, whereas the retrograde refractory period of the accessory pathway increased from 247 +/- 26 to 337 +/- 45 ms in the other patients. Orthodromic atrioventricular reciprocating tachycardia, inducible in 10 patients before therapy, became noninducible in 3 patients. Its rate was significantly slowed in the other 7 patients (from 346 +/- 50 to 471 +/- 81 ms). In 2 patients the tachycardia was nonsustained during flecainide treatment. Atrial fibrillation, inducible in all patients at baseline, was rendered nonsustained and more difficult to induce in 7 patients with flecainide. When isoproterenol was infused during flecainide treatment, complete anterograde (3 patients) or retrograde block (2 patients) persisted in the accessory pathway.(ABSTRACT TRUNCATED AT 250 WORDS)