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: ibasuray@partners.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.
References
1. 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.
2. 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).
