Mechanisms underlying XXXX in @entity1000 : implications for management.

@entity1 @entity2643 @entity1165 @entity737 @entity1000 @entity2778 @entity1167 @entity943 @entity1168 @entity1002
@entity943 ( @entity943 ) have been associated with mortality in @entity1000 ( @entity1000 ). All 3 main mechanisms of arrhythmogenesis - reentry, trigger activity, and automatism - have been implicated. Arrhythmogenic substrates in @entity1000 favor these mechanisms and are often potentiated by electrolyte imbalance secondary to diuretic treatment, by antiarrhythmic drugs, or by @entity1168 , leading to polymorphic @entity1165 ( @entity1165 ). Myocardial macroreentry is the mechanism most frequently responsible for monomorphic @entity1165 in @entity1000 ; however, focal activation and His-Purkinje macroreentry are often responsible and, especially in the latter case, are frequently unrecognized. Clinical suspicion and final recognition by electrophysiologic testing have important therapeutic consequences, because both focal activation and His-Purkinje macroreentry can be treated effectively by catheter ablation. On the other hand, the frequent recurrences of myocardial macroreentrant @entity1165 after ablation require this therapy to be used in combination with drugs or an @entity737 ( @entity737 ). beta-Adrenoceptor antagonists (beta-blockers) have a beneficial effect for primary prevention of @entity943 in @entity1000 . Type III antiarrhythmics have a neutral effect on mortality and type I antiarrhythmics should be avoided. Treatment of nonsustained @entity1165 in @entity1000 is controversial because it often presents without symptoms and is linked more to overall mortality than to arrhythmic mortality. Empiric treatment with @entity2643 or electrophysiologically guided @entity2778 are preferred to the use of other drugs for secondary prevention of sustained @entity943 . ICDs should be implanted in @entity1 who have been resuscitated from @entity1167 due to @entity943 , or in those with poorly tolerated @entity1165 and severe @entity1002 . Empiric treatment with @entity2643 or electrophysiologically guided class III antiarrhythmics may also be alternatives for @entity1 with @entity1000 and no severe @entity1002 , especially if @entity1165 is well tolerated.
