[Atrial standstill: a paralysis of cardiological relevance]

Atrial standstill is a rare arrhythmogenic condition characterized by the absence of electrical and mechanical activity in the atria, transient or persistent, and complete or partial. It can be "idiopathic", sporadic or familial, or secondary to Ebstein's anomaly, Emery-Dreifuss muscular dystrophy (X-linked), Kugelberg-Welander syndrome (autosomal recessive), and amyloidosis. Idiopathic familial atrial standstill is inherited as autosomal dominant trait with variable penetrance. To date, a few cases of familial forms of primary atrial standstill have been described. In each family, the number of affected members was small and limited to relatives of one generation. The genetic basis for familial atrial standstill is unknown. Recently a mutation in the cardiac sodium channel gene SCN5A associated with relatively rare genotypes for two connexin 40 polymorphisms has been reported. The diagnosis relies on the ECG demonstration of bradycardia, absence of P waves, and junctional narrow complex escape rhythm. Nearly 50% of patients suffer from Adams-Stokes attacks. In the primary persistent form, the atrial paralysis is paralleled by atrial dilation, mitral valve incompetence, and thrombotic complications, with high risk of thromboembolic complications. The treatment is addressed to the thromboembolic risk (anticoagulation), mitral incompetence (diuretics and vasodilators) and syncope (pacemaker implantation).