Nonsustained ventricular tachycardia

Proarrhythmia Mexiletine can worsen arrhythmias it is uncommon in patients with less serious arrhythmias (freguent premature beats or nonsustained ventricular tachycardia) but is of greater concern in patients with life-threatening arrhythmias, such as sustained ventricular tachycardia. 

In post-MI patients with asymptomatic PVCs and nonsustained ventricular tachycardia, flecainide therapy was associated with a 5.1% rate of death and nonfatal cardiac arrest, compared with a 2.3% rate in a matched placebo group. 

Supraventricular and ventricular arrhythmias (12%), nonsustained ventricular tachycardia (2%), and sustained ventricular tachycardia (1%) may occur. 

Vitullo RN, Wharton JM, Allen NB, Pritchett EL. Trazodone-related exercise-induced nonsustained ventricular tachycardia. Chest 1990 98(l) 247-8. 

Sustained ventricular tachycardia is defined as consecutive premature ventricular contractions lasting more than 30 seconds. Nonsustained ventricular tachycardia (VT) usually self-terminates and lasts for less than 30 seconds. The acute treatment of SuVT depends on the hemodynamic stability and symptoms of the patient. Unstable patients should receive immediate cardioversion. If patients are stable with mild symptoms, they can be treated with IV antiarrhythmics. 

VT = ventricular tachycardia VF = ventricular fibrillation AMI = acute myocardial infarction Ml = myocardial infarction LV = left ventricular NSVT = nonsustained ventricular tachycardia CAD = coronary artery disease EF = ejection fraction. 

Mitra RL, Buxton AE. The clinical significance of nonsustained ventricular tachycardia. J Cardiovasc Electrophys 1993 4 490-496. 

Wilber DJ, Olshansky B, Moran JF, et al. Electrophysiological testing and nonsustained ventricular tachycardia Use and limitations in patients with coronary artery disease and impaired ventricular function. Circulation 1990 82 350-358. 

Strickberger SA, Hummel JD, Bartlett TG, et al. Amiodarone versus implantable cardioverter-defibrillator randomized trial in patients with nonischemic dilated cardiomyopathy and asymptomatic nonsustained ventricular tachycardia. AMIOVIRT. J Am Coll Cardiol 2003 41 1707-1712. 

Multiple and repetitive or prolonged episodes of nonsustained ventricular tachycardia Marked left ventricular hypertrophy Hypotensive blood pressure response to exercise... 

FIGURE 18-4. Treatment algorithm for hypertrophic cardiomyopathy. ACEI = angiotensin-converting enzyme inhibitor NSVT = nonsustained ventricular tachycardia ICD = implantable cardioverter-defibrillator LV = left ventricular SCD = sudden cardiac death. 

Severe nausea, vomiting, drowsiness, prolonged QT, and episodes of nonsustained ventricular tachycardia were reported in a 34-year-old woman who had taken three or four 500 mg capsules of passionflower daily for several days. A sample of the product taken by the patient was analyzed and compared to other capsules produced by the same manufacturer and to other commercial samples of passionflower, and also tested for the presence of two... 

Noninvasive markers have been evaluated to help identify high-risk patients. Ventricular ectopy is associated with an increased risk for cardiac arrest. Premature ventricular contractions (PVCs) and nonsustained ventricular tachycardia identify increased risk for death, even in patients with no obvious heart disease (40-43). PVCs and nonsustained ventricular tachycardia provide... 

MUSTT (Multicenter UnSustained Tachycardia Trial), a large randomized trial of patients with nonsustained ventricular tachycardia, coronary artery disease, and impaired left ventricular function indicated that electrophysiol-... 

MADIT was the first randomized trial to show that the ICD, used as a prophylactic, can reduce the risk of death in high-risk patients. The MADIT assessed patients who had coronary artery disease and a prior Q-wave myocardial infarction. To be included, patients had to have (a) asymptomatic nonsustained ventricular tachycardia recorded on a 24-h Hotter monitor, (b) a left ventricular ejection fraction of < 0.35 and, (c) inducible sustained monomorphic ventricular tachycardia or ventricular fibrillation not suppressed by procainamide at electrophysiology testing. 

Class I Indications for an ICD (1) Survivors of cardiac arrest secondary to ventricular tachycardia and ventricular fibrillation except when due to a reversible cause. (2) Sustained vaitricular tachycardia associated with structural heart disease. (3) Syncope of unclear etiology with an inducible ventricular tachycardia or ventricular fibrillation at electrophysiology study. (4) Nonsustained ventricular tachycardia in patients with coronary artery disease, left ventricular dysfunction, and inducible ventricular tachycardia or fibrillation at electrophysiology study that is not suppressed will by an antiarrhythmic drug. (5) Spontaneous sustained ventricular tachycardia in patients without structural heart disease who are not amenable to medical therapy. 

Patients with syncope, heart failure, and impaired ventricular function are at high risk to die from SCD (184,185). We do not know, however, that an ICD will protect such patients from dying. With the recent wave of enthusiasm for ICD implants, temperance and prudent judgment must be employed. Not every event requires an ICD implant in a high-risk patient. It is even conceivable that a patient may trip on a rug at home only to find that a physician wants to top it off with an ICD implant. Risks of infection and inappropriate ICD discharge (a proarrhythmic effect of the ICD) may outweigh the benefit of implant in some patients. ICDs can transform an episode of nonsustained ventricular tachycardia into ventricular fibrillation, for example, and be proarrhythmic (186). 

ICD placement in patient with nonsustained ventricular tachycardia, history of coronary artery disease, left ventricular dysfunction, and an inducible ventricular arrhythmia at an electrophysiology study is indicated as per MADIT criteria. However, these data are supplanted by SCD-HeFT which indicates that an ICD implant is appropriately independent of electrophysiology test results. A controversial area is ICD implantation in patients without structural heart disease who have spontaneous sustained ventricular tachycardia that is not amenable to medical therapy. We do not ascribe to this indication based on lack of data indicating the need for an ICD unless the ventricular tachycardia is polymorphic associated with evidence for a channelopathy such as long QT interval. 

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