Ventricular tachycardia (often called VT, for short) is a form of heart racing that starts inside the right or left ventricle. It is most commonly due to damage or scarring of the lower heart chambers, usually as a result of a previous heart attack. However, any disease that damages the heart can cause ventricular tachycardia to occur later in life. The time period between when the heart damage occurs and when ventricular tachycardia first develops can be days, months or up to many years. In someone who has heart disease, ventricular tachycardia is considered a potentially dangerous arrhythmia that requires careful treatment. Rarely, ventricular tachycardia can occur in healthy, young individuals without any history of heart disease(called idiopathic or primary VT). In these people, VT is NOT a dangerous problem but is nonetheless bothersome. With ventricular tachycardia, the heart can race at 130-250 beats per minute. Often, lightheadedness and blackouts can accompany the feeling of palpitations. Chest discomfort and shortness of breath may also be noticed
In patients whose VT is caused by previous damage or scarring of their hearts, catheter ablation is not often a good first choice for treatment. Drug therapy to try and suppress attacks or implantation of an implantable cardioverter defibrillator (ICD for short) is preferred. Ablation therapy may be used in conjunction with the others to help reduce the frequency of attacks.

In VT patients who otherwise have normal hearts, catheter ablation is an alternative to drug therapy and can be curative. However, VT ablation can be more difficult because it may be difficult to turn on the VT at the time of the EP study. If the VT cannot be triggered, it is impossible to map and ablation cannot be done. This can happen in 25-40% of patients. The risks of VT ablation are usually less than 1-3%.