VENTRICULAR-TACHYCARDIA IN ISCHEMIC-HEART -DISEASE

Ventricular tachycardia in patients with ischemic heart disease are al most always observed after myocardial infarction without preservation of the border zone (thrombolysis or early angioplasty). Monomorphic ta chycardias are related to permanent electrophysiological substrate wit h a zone of slow conduction. This may be affected by initiating factor s such as extrasystoles, especially with alternating long and short cy cles, and the sympathetic nervous system before the appearance of clin ical tachycardia. Cardiac mortality is mainly due to sudden death afte r an initial episode of sustained monomorphic ventricular tachycardia. The prognostic value of left ventricular function as assessed by the ejection fraction is essential : the 5-year mortality is 30 % if LVEF is > 0.3 compared with 51 % if LVEF is < 0.3 (p < 0.01). On the other hand, the frequency of spontaneous VT and VT induced by programmed sti mulation does not affect the prognosis. The mortality after an initial episode of syncopal tachycardia is greater than after a well tolerate d tachycardia. This is why the clinical history of the patient is esse ntial to guide management. The persistence of inducible VT despite ant iarrhythmic therapy increases the mortality ; it is therefore importan t to find a drug which prevents induction VT. The patient is then clas sified as << responder >>. The number of << responders >> patients, ho wever, is low when the ejection fraction is less-than-or-equal-to 0.30 . The choice of treatment seems important when the ejection fraction i s less-than-or-equal-to 0.30 : in this case, patients receiving Class I antiarrhythmics have a higher mortality and those taking betablocker s have a reduced mortality. After polymorphic VT, if VT or VF is induc ible, the risk of mortality is very high. Therefore, most teams consid er these patients, like those who have had syncopal monomorphic VT or cardiac arrest, to be candidates for implantable cardioverter defibril lators as treatment of first intention.