Mortality: The National Heart, Lung, and Blood Institute's Cardiac Arrhythmia
Suppression Trial I (CAST I) was a long-term, multicenter, double-blind study
in patients with asymptomatic, non-life-threatening ventricular arrhythmias,
1to 103 weeks after acute myocardial infarction. Patients in CAST I were randomized
to receive placebo or individually optimized doses of encainide, flecainide,
or moricizine. The Cardiac Arrhythmia Suppression Trial II (CAST II) was similar,
except that the recruited patients had had their index infarction 4 to 90 days
before randomization, patients with left ventricular ejection fractions greater
than 40% were not admitted, and the randomized regimens were limited to placebo
and moricizine.
CAST Iwas discontinued after an average time-on-treatment of 10 months,
and CAST II was discontinued after an average time-on-treatment of 18 months.
As compared to placebo treatment, all three active therapies were associated
with increases in short-term (14-day) mortality, and encainide and flecainide
were associated with significant increases in longer-term mortality as well.
The longer-term mortality rate associated with moricizine treatment could not
be statistically distinguished from that associated with placebo.
The applicability of these results to other populations (e.g., those without
recent myocardial infarction) and to other than Class I antiarrhythmic agents
is uncertain. BETAPACE (sotalol hydrochloride) is devoid of Class I effects,
and in a large (n=1,456) controlled trial in patients with a recent myocardial
infarction, who did not necessarily have ventricular arrhythmias, BETAPACE did
not produce increased mortality at doses up to 320 mg/day (see Clinical
Actions). On the other hand, in the large post-infarction study using
a non-titrated initial dose of 320 mg once daily and in a second small randomized
trial in high-risk post-infarction patients treated with high doses (320 mg
BID), there have been suggestions of an excess of early sudden deaths.
Proarrhythmia
Like other antiarrhythmic agents, BETAPACE can provoke new or worsened ventricular
arrhythmias in some patients, including sustained ventricular tachycardia or
ventricular fibrillation, with potentially fatal consequences. Because of its
effect on cardiac repolarization (QTc interval prolongation), Torsade
de Pointes, a polymorphic ventricular tachycardia with prolongation of the QT
interval and a shifting electrical axis is the most common form of proarrhythmia
associated with BETAPACE, occurring in about 4% of high risk (history of sustained
VT/VF) patients. The risk of Torsade de Pointes progressively increases with
prolongation of the QT interval, and is worsened also by reduction in heart
rate and reduction in serum potassium. (See Electrolyte Disturbances.)
Because of the variable temporal recurrence of arrhythmias, it is not always
possible to distinguish between a new or aggravated arrhythmic event and the
patient‘s underlying rhythm disorder. (Note, however, that Torsade de Pointes
is usually a drug-induced arrhythmia in people with an initially normal QTc.)
Thus, the incidence of drug-related events cannot be precisely determined, so
that the occurrence rates provided must be considered approximations. Note also
that drug-induced arrhythmias may often not be identified, particularly if they
occur long after starting the drug, due to less frequent monitoring. It is clear
from the NIH-sponsored CAST (see WARNINGS: Mortality) that some antiarrhythmic
drugs can cause increased sudden death mortality, presumably due to new arrhythmias
or asystole, that do not appear early in treatment but that represent a sustained
increased risk.
Overall in clinical trials with sotalol, 4.3% of 3257 patients experienced
a new or worsened ventricular arrhythmia. Of this 4.3%, there was new or worsened
sustained ventricular tachycardia in approximately 1% of patients and Torsade
de Pointes in 2.4%. Additionally, in approximately 1% of patients, deaths were
considered possibly drug-related; such cases, although difficult to evaluate,
may have been associated with proarrhythmic events. In patients with a history
of sustained ventricular tachycardia, the incidence of Torsade de Pointes was
4% and worsened VT in about 1%; in patients with other, less serious, ventricular
arrhythmias and supraventricular arrhythmias, the incidence of Torsade de Pointes
was 1% and 1.4%, respectively.
Torsade de Pointes arrhythmias were dose related, as is the prolongation of
QT (QTc) interval, as shown in the table below.
Percent Incidence of Torsade de Pointes and Mean QTc
Interval by Dose For Patients With Sustained VT/VF
| Daily Dose (mg) |
Incidence of Torsade de Pointe |
s Mean QTc* (msec) |
| 80 |
0 (69) |
463 (17) |
| 160 |
0.5 (832) |
467 (181) |
| 320 |
1.6 (835) |
473 (344) |
| 480 |
4.4 (459) |
483 (234) |
| 640 |
3.7 (324) |
490 (185) |
| > 640 |
5.8 (103) |
512 (62) |
( ) Number of patients assessed
* highest on-therapy value |
In addition to dose and presence of sustained VT, other risk factors for Torsade
de Pointes were gender (females had a higher incidence), excessive prolongation
of the QTc interval (see table below) and history of cardiomegaly or
congestive heart failure. Patients with sustained ventricular tachycardia and
a history of congestive heart failure appear to have the highest risk for serious
proarrhythmia (7%). Of the patients experiencing Torsade de Pointes, approximately
two-thirds spontaneously reverted to their baseline rhythm. The others were
either converted electrically (D/C cardioversion or overdrive pacing) or treated
with other drugs (see OVERDOSAGE). It is not possible to determine whether
some sudden deaths represented episodes of Torsade de Pointes, but in some instances
sudden death did follow a documented episode of Torsade de Pointes. Although
BETAPACE therapy was discontinued in most patients experiencing Torsade de Pointes,
17% were continued on a lower dose.
Nonetheless, BETAPACE should be used with particular caution if the QTc
is greater than 500 msec on-therapy and serious consideration should be given
to reducing the dose or discontinuing therapy when the QTc exceeds
550 msec. Due to the multiple risk factors associated with Torsade de Pointes,
however, caution should be exercised regardless of the QTc interval.
The table below relates the incidence of Torsade de Pointes to on-therapy QTc
and change in QTc from baseline. It should be noted, however, that
the highest on-therapy QTc was in many cases the one obtained at
the time of the Torsade de Pointes event, so that the table overstates the predictive
value of a high QTc .
Relationship Between QTc Interval Prolongation
and Torsade de Pointes
| On-Therapy QTc Interval (msec) |
Incidence of Torsade de Pointes |
Change in QTc Interval From Baseline
(msec) |
Incidence of Torsade de Pointes |
| < 500 |
1.3% (1787) |
< 65 |
1.6% (1516) |
| 500-525 |
3.4% (236) |
65-80 |
3.2% (158) |
| 525-550 |
5.6% (125) |
80-100 |
4.1% (146) |
| > 550 |
10.8% (157) |
100-130 |
5.2% (115) |
| |
|
> 130 |
7.1% (99) |
| ( ) Number of patients assessed |
Proarrhythmic events must be anticipated not only on initiating therapy,
but with every upward dose adjustment. Proarrhythmic events most often occur
within 7 days of initiating therapy or of an increase in dose; 75% of serious
proarrhythmias (Torsade de Pointes and worsened VT) occurred within 7 days of
initiating BETAPACE therapy, while 60% of such events occurred within 3 days
of initiation or a dosage change. Initiating therapy at 80 mg BID with gradual
upward dose titration and appropriate evaluations for efficacy (e.g., PES or
Holter) and safety (e.g., QT interval, heart rate and electrolytes) prior to
dose escalation, should reduce the risk of proarrhythmia. Avoiding excessive
accumulation of sotalol in patients with diminished renal function, by appropriate
dose reduction, should also reduce the risk of proarrhythmia (see DOSAGE
AND ADMINISTRATION).
Congestive Heart Failure
Sympathetic stimulation is necessary in supporting circulatory function in
congestive heart failure, and beta-blockade carries the potential hazard of
further depressing myocardial contractility and precipitating more severe failure.
In patients who have congestive heart failure controlled by digitalis and/or
diuretics, BETAPACE should be administered cautiously. Both digitalis and sotalol
slow AV conduction. As with all beta-blockers, caution is advised when initiating
therapy in patients with any evidence of left ventricular dysfunction. In premarketing
studies, new or worsened congestive heart failure (CHF) occurred in 3.3% (n=3257)
of patients and led to discontinuation in approximately 1% of patients receiving
BETAPAC.E. The incidence was higher in patients presenting with sustained ventricular
tachycardia/fibrillation (4.6%, n=1363), or a prior history of heart failure
(7.3%, n=696). Based on a life-table analysis, the one-year incidence of new
or worsened CHF was 3% in patients without a prior history and 10% in patients
with a prior history of CHF. NYHA Classification was also closely associated
to the incidence of new or worsened heart failure while receiving BETAPACE (1.8%
in 1395 Class I patients, 4.9% in 1254 Class II patients and 6.1% in 278 Class
III or IV patients).
Electrolyte Disturbances
BETAPACE should not be used in patients with hypokalemia or hypomagnesemia
prior to correction of imbalance, as these conditions can exaggerate the degree
of QT prolongation, and increase the potential for Torsade de Pointes. Special
attention should be given to electrolyte and acid-base balance in patients experiencing
severe or prolonged diarrhea or patients receiving concomitant diuretic drugs.
Conduction Disturbances
Excessive prolongation of the QT interval ( > 550 msec) can promote serious
arrhythmias and should be avoided (see Proarrhythmia above). Sinus bradycardia
(heart rate less than 50 bpm) occurred in 13% of patients receiving BETAPACE
in clinical trials, and led to discontinuation in about 3% of patients. Bradycardia
itself increases the risk of Torsade de Pointes. Sinus pause, sinus arrest and
sinus node dysfunction occur in less than 1% of patients. The incidence of 2nd-
or 3rd-degree AV block is approximately 1%.
Recent Acute MI
BETAPACE can be used safely and effectively in the long-term treatment of
life-threatening ventricular arrhythmias following a myocardial infarction.
However, experience in the use of BETAPACE to treat cardiac arrhythmias in the
early phase of recovery from acute MI is limited and at least at high initial
doses is not reassuring. (See WARNINGS: Mortality.) In the first 2 weeks
post-MI caution is advised and careful dose titration is especially important,
particularly in patients with markedly impaired ventricular function.
The following warnings are related to the beta-blocking activity of BETAPACE.
Abrupt Withdrawal
Hypersensitivity to catecholamines has been observed in patients withdrawn
from beta-blocker therapy. Occasional cases of exacerbation of angina pectoris,
arrhythmias and, in some cases, myocardial infarction have been reported after
abrupt discontinuation of beta-blocker therapy. Therefore, it is prudent when
discontinuing chronically administered BETAPACE, particularly in patients with
ischemic heart disease, to carefully monitor the patient and consider the temporary
use of an alternate beta-blocker if appropriate. If possible, the dosage of
BETAPACE should be gradually reduced over a period of one to two weeks. If angina
or acute coronary insufficiency develops, appropriate therapy should be instituted
promptly. Patients should be warned against interruption or discontinuation
of therapy without the physician's advice. Because coronary artery disease is
common and may be unrecognized in patients receiving BETAPACE, abrupt discontinuation
in patients with arrhythmias may unmask latent coronary insufficiency.
Non-Allergic Bronchospasm (e.g., chronic bronchitis and emphysema)
PATIENTS WITH BRONCHOSPASTIC DISEASES SHOULD IN GENERAL NOT RECEIVE BETA-BLOCKERS.
It is prudent, if BETAPACE (sotalol hydrochloride) is to be administered, to
use the smallest effective dose, so that inhibition of bronchodilation produced
by endogenous or exogenous catecholamine stimulation of beta2 receptors
may be minimized.
Anaphylaxis
While taking beta-blockers, patients with a history of anaphylactic reaction
to a variety of allergens may have a more severe reaction on repeated challenge,
either accidental, diagnostic or therapeutic. Such patients may be unresponsive
to the usual doses of epinephrine used to treat the allergic reaction.
Anesthesia
The management of patients undergoing major surgery who are being treated
with beta-blockers is controversial. Protracted severe hypotension and difficulty
in restoring and maintaining normal cardiac rhythm after anesthesia have been
reported in patients receiving beta-blockers.
Diabetes
In patients with diabetes (especially labile diabetes) or with a history of
episodes of spontaneous hypoglycemia, BETAPACE should be given with caution
since beta-blockade may mask some important premonitory signs of acute hypoglycemia;
e.g., tachycardia.
Sick Sinus Syndrome
BETAPACE should be used only with extreme caution in patients with sick sinus
syndrome associated with symptomatic arrhythmias, because it may cause sinus
bradycardia, sinus pauses or sinus arrest.
Thyrotoxicosis
Beta-blockade may mask certain clinical signs (e.g., tachycardia) of hyperthyroidism.
Patients suspected of developing thyrotoxicosis should be managed carefully
to avoid abrupt withdrawal of beta-blockade which might be followed by an exacerbation
of symptoms of hyperthyroidism, including thyroid storm.