Indian Pacing Electrophysiol. J.
Indian Pacing Electrophysiol. J. 2002;
Latest Updates In EP
Indranill Basu Ray
Address for correspondence: Dr. Indranill Basu Ray, Cardiac Arrythmia Service, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, GRB109, Boston, MA, USA 12114. E-mail: firstname.lastname@example.org
We are starting a new section called ‘Latest Updates in EP’. This section intends to bring to the readers of IPEJ latest updates from EP/ Cardiology conferences worldwide. This section will also scan latest trial updates/ review topics from journals & present them to the reader. Anybody attending any EP/Cardiology conference is welcome to submit their contributions through my email.
This week I summarize presentations at the European Society of Cardiology amongst others.
Drug Therapy Adverse Effects Favor Rate Than Rhythm Control
Side effects of antiarrhythmic drug (AAD) therapy -- not inefficacy -- are responsible for the inability of rhythm control to maintain long-term sinus rhythm, according to an analysis from the Rate Control vs. Electrical Cardioversion (RACE) study.1
Presenting the data at the European Society of Cardiology 2003 Congress (Vienna, Austria), Eduard H. Hoekstra, MD, University Hospital (Groningen, The Netherlands) on behalf of the RACE investigators reported that long-term maintenance of sinus rhythm was significantly reduced by the side effects of sotalol and amiodarone and the discontinuation amiodarone, but not by clinical characteristics. They suggested that the high incidence of side effects from the drugs is responsible for the failure of rhythm control to show superiority over rate control for the treatment of atrial fibrillation (AF), as reported in several large randomized trials. The current analysis was designed to determine the actual number of AAD side effects, their clinical characteristics, and relation of the side-effects to the failure of long-term maintenance of sinus rhythm in the 266 patients with AF (</= 6 months) randomized to the rhythm control arm of the RACE study. Patients enrolled in the study had persistent AF despite previous electrical cardioversion. Baseline clinical characteristics were "typical" of a patient population with persistent AF; 91% of rhythm patients presented with >/= 1 risk factor for stroke.2
After randomization, rhythm control patients underwent serial electrical cardioversions. Additionally, they received serial AADs -- initially sotalol, then flecainide, and finally amiodarone, if appropriate -- as well as oral anticoagulants, as needed. Investigators analyzed AAD side effects during mean follow-up of 2.3 ± 0.6 years. At the end of the study, 39% of patients were in sinus rhythm.The side effects of sotalol and amiodarone were associated with a significant reduction in long-term maintenance of sinus rhythm (P = 0.41 and P = .025, respectively). Discontinuation of amiodarone therapy was also associated with a significant reduction in long-term maintenance of sinus rhythm (P = .009). Based on the findings, investigators concluded that the side effects of AADs, not the inefficacy of the drugs, contribute to the failure of rhythm control.Investigators believe that the importance of sinus rhythm may be overlooked to a certain extent. They stated that despite the fact that AADs are known to be effective, the associated side effects of the drugs and the high rate of discontinuation are "responsible for [the] acceptance of AF." Ultimately, if drugs had fewer side effects, fewer patients would stop their medications, and the end result is that more rhythm control patients would be in sinus rhythm.
Hoekstra EH, Hagens VE, Bosker HA, et al. Importance of side effects of antiarrhythmic drugs to failure of rhythm control in the RACE study. European Society of Cardiology Congress 2003, August 30-September 3, 2003. Abstract P2751.
Van Gelder IC, Hagens VE, Bosker HA, et al. A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. N Engl J Med. 2002;347:1834-1840.
RF Ablation of Triggers May Reduce Ventricular Arrhythmia in Long QT/ Brugada
The long-QT and Brugada syndromes are important substrates of malignant ventricular arrhythmia. The feasibility of mapping and ablation of ventricular arrhythmias in these conditions has not been reported. Haissaguerre et al reported in Circulation 2003 Aug 26;108(8):925-8 a study of 7 patients (4 men; age, 38+/-7 years; 4 with long-QT and 3 with Brugada syndrome) with episodes of ventricular fibrillation or polymorphic ventricular tachycardia and frequent isolated or repetitive premature beats. These premature beats were observed to trigger ventricular arrhythmias and were localized by mapping the earliest endocardial activity. In 4 patients, premature beats originated from the peripheral right (1 Brugada) or left (3 long-QT) Purkinje conducting system and were associated with variable Purkinje-to-muscle conduction times (30 to 110 ms). In the remaining 3 patients, premature beats originated from the right ventricular outflow tract, being 25 to 40 ms ahead of the QRS. The accuracy of mapping was confirmed by acute elimination of premature beats after 12+/-6 minutes of radiofrequency applications. During a follow-up of 17+/-17 months using ambulatory monitoring and defibrillator memory interrogation, no patients had recurrence of symptomatic ventricular arrhythmia but 1 had persistent premature beats. This led them to the conclusion that Triggers from the Purkinje arborization or the right ventricular outflow tract have a crucial role in initiating ventricular fibrillation associated with the long-QT and Brugada syndromes. These can be eliminated by focal radiofrequency ablation
Amiodarone to Prevent Post-op A Fib.
New onset Atrial Fibrillation is common after surgery. Tahir Yagdi et al reported a study in the J Thorac Cardiovasc Surg 2003;125:1420-1425 to test the hypothesis that preoperative Amiodarone reduced the incidence of postop A Fib.157 patients were taken & randomly divided into two groups: 77 patients (amiodarone group) received intravenous amiodarone in a dose of 10 mg/kg/d for postoperative 48 hours. On postoperative day 2 oral amiodarone was started with a dose of 600 mg/d for 5 days, 400 mg/d for the following 5 days, and 200 mg/d for 20 days, and 80 patients received placebo (control group). Preoperative patient characteristics and operative variables were similar in the two groups. Postoperative atrial fibrillation occurred in 8 patients (10.4%) receiving amiodarone and in 20 (25.0%) patients receiving placebo (P = .017). Duration of atrial fibrillation was 12.8 ± 4.8 hours for the amiodarone group compared with 34.7 ± 28.7 hours for the control group (P = .003). The maximum ventricular rate during atrial fibrillation was slower in the amiodarone group than in the control group (105.9 ± 19.1 beats per minute and 126.0 ± 18.5 beats per minute, respectively, P = .016). The two groups had a similar incidence of complication other than rhythm disturbances (20.8% vs 20.0%, P = .904). Amiodarone group patients had shorter hospital stays than that of control group patients (6.8 ± 1.7 days vs 7.8 ± 2.9 days, P = .014). The in-hospital mortality was not different between two groups (1.3% vs 3.8, P = .620). In this study they concluded that postoperative intravenous amiodarone, followed by oral amiodarone, is effective in the prevention of new-onset postoperative atrial fibrillation. It also reduces ventricular rate and duration of atrial fibrillation after coronary artery bypass grafting. It is well tolerated and decreases the length of hospital stay.
Amiodarone has been used & is used however so are beta blockers to prevent postop A Fib. There is as of present no well controlled trial comparing these two regimens. Obviously if proved equally effective then beta blockers would be the obvious choice.
AFib of Non-PV Origin
Most of the ectopic beats initiating paroxysmal atrial fibrillation (PAF) originate from the pulmonary vein (PV). However, only limited data are available on PAF originating from the non-PV areas. This study reported in circulation shows the efficacy of ablating PAF from non PV sources (Wei-Shiang Lin et al Circulation. 2003;107:3176).Two hundred forty patients with a total of 358 ectopic foci initiating PAF were included. Sixty-eight (28%) patients had AF initiated by ectopic beats (73 foci, 20%) from the non-PV areas, including the left atrial posterior free wall (28, 38.3%), superior vena cava (27, 37.0%), crista terminalis (10, 3.7%), ligament of Marshall (6, 8.2%), coronary sinus ostium (1, 1.4%), and interatrial septum (1, 1.4%). Catheter ablation eliminated AF with acute success rates of 63%, 96%, 100%, 50%, 100%, and 0% in left atrial posterior free wall, superior vena cava, crista terminalis, ligament of Marshall, coronary sinus ostium, and interatrial septum, respectively. During a follow-up period of 22±11 months, 43 patients (63.2%) were free of antiarrhythmic drugs without AF recurrence.The authors in this study concluded that ectopic beats initiating PAF can originate from the non-PV areas, and catheter ablation of the non-PV ectopy has a moderate efficacy in treatment of PAF.
Atrial Overdrive Reduced AF Incidence
The Atrial Dynamic Overdrive Pacing Trial (ADOPT) was a single blind, randomized, controlled study to evaluate the efficacy and safety of the atrial fibrillation (AF) Suppression Algorithm (St. Jude Medical Cardiac Rhythm Management Division, Sylmar, California) in patients with sick sinus syndrome and AF. This study helps to prove a long suspected point that had emerged from other pacemaker trials. Mark D. Carlson et al JACC 20 August 2003, Volume 42, Issue 4 Pages 627-633 used a special algorithm that increases the pacing rate when the native rhythm emerges and periodically reduces the rate to search for intrinsic atrial activity. Symptomatic AF burden (percentage of days during which symptomatic AF occurred) was the primary end point. Patients underwent pacemaker implantation, were randomized to DDDR with the algorithm on (treatment) or off (control), and were followed for six months.Baseline characteristics and antiarrhythmic drugs used were similar in both groups. The percentage of atrial pacing was higher in the treatment group (92.9% vs. 67.9%, p < 0.0001). The AF Suppression Algorithm reduced symptomatic AF burden by 25% (2.50% control vs. 1.87% treatment). Atrial fibrillation burden decreased progressively in both groups but was lower in the treatment group at each follow-up visit (one, three, and six months) (p = 0.005). Quality of life scores improved in both groups. The mean number of AF episodes (4.3 ± 11.5 control vs. 3.2 ± 8.6 treatment); total hospitalizations (17 control vs. 15 treatment); and incidence of complications, adverse events, and deaths were not statistically different between groups. The authors of this trial concluded that that overdrive atrial pacing with the AF Suppression Algorithm decreased symptomatic AF burden significantly in patients with sick sinus syndrome and AF. The decrease in relative AF burden was substantial (25%), although the absolute difference was small (2.50% control vs. 1.87% treatment).