Aspirine ou héparine in FA ? réponses en partie dans :
Rodney H. Falk. Atrial Fibrillation. NEJM. Volume
344:1067-1078. April 5, 2001
Newly Diagnosed Atrial Fibrillation
Anticoagulation
In many patients, the precise time of onset of atrial fibrillation cannot be determined accurately. Under these circumstances, it is highly advisable to administer
anticoagulant therapy to the patient before attempting cardioversion. There are two alternative approaches: outpatient systemic anticoagulation with warfarin to
achieve an international normalized ratio of 2.0 to 3.0 for at least three weeks, followed by cardioversion; and cardioversion guided by transesophageal
echocardiography. In the latter approach, multiplane transesophageal echocardiography that indicates the absence of thrombus is associated with an extremely low
rate of thromboembolism after cardioversion,49 provided that short-term anticoagulant therapy is used before and during the procedure and that warfarin is
prescribed after the procedure. Regardless of which of these approaches is taken, anticoagulant therapy is mandatory for a minimum of three to four weeks after
cardioversion. Since the greatest likelihood of reversion to atrial fibrillation occurs in the first three months after the restoration of sinus rhythm,50 it is prudent to
continue anticoagulation for this period unless there is a contraindication.
Recurrent Paroxysmal Atrial Fibrillation
Long-Term Anticoagulation
Several large trials have demonstrated the efficacy of warfarin for the prevention of stroke in patients with atrial fibrillation. Both the risk of stroke and the
efficacy of warfarin among patients with persistent arrhythmia were equivalent to those among patients with paroxysmal arrhythmia. A high rate of intracranial
hemorrhage complicated the use of warfarin in elderly patients in one trial (the Stroke Prevention in Atrial Fibrillation II study),65 but analysis of the degree of
anticoagulation at the time of bleeding indicated that virtually all episodes occurred at an international normalized ratio greater than 3.0.66 Subsequent analyses
suggest that the optimal international normalized ratio for the prevention of stroke in patients with atrial fibrillation lies between 2.0 and 3.0.67,68 Pooled data
from the anticoagulation trials offer insights into risk stratification with respect to stroke. Clinical risk factors included a previous stroke or transient ischemic attack,
hypertension (current or past), an age of more than 70 years, diabetes, and congestive heart failure.51,69
The role of aspirin in the prevention of stroke in patients with atrial fibrillation remains controversial. In one trial, aspirin, in a prescribed dose of 325 mg daily,
reduced the annual rate of stroke by 42 percent, as compared with placebo (absolute reduction, from 6.3 percent to 3.6 percent).70 A statistically insignificant
reduction was found in two other trials, one of which included only high-risk patients who had had a previous stroke or transient ischemic attack.71 The other trial
used a lower dose of aspirin (82 mg).72 Aspirin (325 mg) prescribed in conjunction with "mini-dose" warfarin (1 to 3 mg daily) was also found to be ineffective for
the prevention of stroke in patients with clinical risk factors.69 The Stroke Prevention in Atrial Fibrillation III investigators studied the effects of 325 mg of
aspirin alone in a group of patients initially believed to be at low risk for stroke.69,73 The stroke rate was 2.2 percent per year among the patients for whom aspirin
was prescribed but was higher in the subgroup with a history of hypertension (3.6 percent per year, as compared with 1.1 percent among the patients who had never
had hypertension).73 Although this study demonstrated that it is possible to identify a cohort of patients with atrial fibrillation and a low risk of stroke, it did not
have a placebo group and thus did not prove that aspirin is superior to no therapy.
Recommendations for antithrombotic therapy in patients with atrial fibrillation are summarized in Table 3. As a rule of thumb, all patients with atrial
fibrillation should receive long-term anticoagulant therapy with warfarin unless they are young (younger than 65 years old) and have none of the risk factors
described above, or unless there is a major contraindication to the use of warfarin. In the absence of risk factors, aspirin alone (or no antithrombotic therapy) may be
adequate.74 Advanced age is a risk factor for both stroke and bleeding in patients receiving anticoagulation therapy. However, the relative risk of stroke exceeds that
of bleeding, and whenever possible, elderly patients with atrial fibrillation should receive warfarin therapy.67
axel ellrodt a *crit :
Aspirine ou héparine in AVC (CVA)
http://www.33docpro.com/fonds_documentaire/annexes/zuber.pdf
taboulet a écrit :
Alain Vadeboncoeur MD a *crit :
Taboulet
disait: En
tout cas, il faut anticoaguler les FA en phase aiguë.**
**Intéressante l'idée
qu'il FAUT anticoaguler les FA en phase aigue. Vraiment? Voyons diverses
possibilités:1) FA chez patient avec coeur normal, jeune, bas risque,
moins de 2% de chances de faire annuellement une embolie. Arrive à
l'urgence en FA. Conversion spontanée. Doit-on anticoaguler?
-
Non, c'est vrai. D'ailleurs
la conversion spontanée d'un premier épisode de FA paroxystique
survient jusque dans deux tiers des cas (Danias). Mais,
les FA isolées, c'est-à-dire sur c�ur sain et sans hypertension
artérielle, ne constituent que 3% des cas de FA (Kopecky).
Elles sont plutôt d'origine vagale (plutôt homme 30-50 ans,
période nocturne, digestion, prise d'alcool) qu'adrénergique
(Coumel). Leur pronostic est bénin avant 60 ans et le risque d'accident
embolique cérébral est faible (Falk). Les accès sont
dits paroxystiques s'ils durent moins de sept jours.
2) FA découverte
fortuite ou de longue date chez patient à bas risque. Comme ça
arrive si souvent en bureau. Doit-on anticoaguler maintenant ou peut-on
simplement débuter les AVK? Le risque d'ACV est faible (< 2%
par année, donc minime à court terme), le risque d'une héparinisation
n'est pas négligeable (> 1% d'hémorragie majeure dans les
séries sur l'angine instable), donc le risque vs le gain??? Même
chez le patient à plus haut risque, le risque annuel est faible,
alors quel est le risque pour les 3 ou 4 prochains jours jusqu'à
ce que les AVK agissent? Démarrer des AVK chez des patients ambulants
sans "couverture" héparinique se fait partout et très largement.
Mauvaise pratique, vraiment?
-
Ce n'est pas de la phase aiguë. Et puis çà
revient quand même à anticoaguler le patient. Et c'est davantage
de la pratique que les recommandations officielles (Guidelines 2000 for
cardiopulmonary resuscitation and emergency cardiovascular care. Circulation
2000, 102(suppl I).
3) FA < 48 heures, CVE électrique ou chimique
à l'urgence sous héparine, pas d'indication à long
terme d'AVK, OK avec héparine (bien que les données soient
certainement empiriques dans ce contexte précis), mais doit-on démarrer
les AVK?
-
En tout cas; il faut anticoaguler au moins 4 semaines.
Ciao. P Taboulet. MD
----- Original Message -----
Sent: Monday, December 10, 2001 5:15
AM
Subject: URG-L: FA et accident isch*mique
c*r*bral.
paulaye a *crit :
Il n'y a effectivement aucun argument dzans la
littérature pour anticoaguler
(a doses thérapeutiques) les AVC sur FA en phase aiguë...
En tout cas, il faut anticoaguler les FA en phase
aiguë. Alors il me paraissait logique
d'anticoaguler les AVC sur FA en phase aiguë. Ce qui est "sûr",
c'est que l'anticoagulation des gros AVC est délétère
par le risque, comme tu le dit, de ramollissement secondaire hémorragique.
Mon attitude était donc variable en fonction des images scannorgraphiques
et de la clinique. Gros AVC, anticoagulation douce au début, et
petit AVC, anticoagulation efficace. Depuis la synthese (précedement
jointe en pdf), l'idée de l'aspirine me plait en cas de gros AVC
en association d'emblée avec la warfarine qui mettra plusieurs jours
pour être efficace. A signaler que le NEJM
se permet de recommander les HBPM sur le même niveau que l'héparine
non fractionnée à la phase aiguë d'une FA. C'est
quand même bien utile de s'appuyer sur cette recommandation. : Falk
RH. Atrial fibrillation. N. Engl. J. Med. 2001; 14 : 1067-1078.
--
Dr Axel Ellrodt
Essonne, France
http://zzorglub.ifrance.com/
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