Sustained ventricular arrhythmias : population based study of presentation, management and mortality

BACKGROUND: Sudden cardiac death (SCD) due ventricular tachycardia (VT) or fibrillation (VF) is a major cause of death in the developed world. It is associated with a high recurrence rate and poor prognosis. There has been very little published about VT/VF in a population setting. In this thesis, the incidence of VT/VF, patient demographics, management and survival in a population setting are examined. METHODS: During the two year period between 1 February 1997 and 31 January 1999, all patients presenting with a sustained episode of VT/VF, unrelated to an AMI, to all 32 coronary care units in the Midlands region of England (population 9.1 million) were entered into a registry. Demographics, clinical history, management as well as mortality data were collected. RESULTS: Six hundred and eight-nine patients presenting with VT/VF were registered giving a minimum annual incidence rate of 38 per million population. Two hundred and nine (30%) of patients underwent electrophysiology (EP)-guided therapy with 89 ICDs implanted. Fifty patients underwent coronary artery bypass grafting (CABG) during the index admission. There were 210 (30%) deaths in total of which 10 were following CABG. EP-guided treatment did not confer a survival benefit but ICD treatment did despite relatively small numbers of ICDs implanted. The benefit of ICD therapy was most impressive in patients with poorer LVEF. Age, VT/VF needing defibrillation, reduced LVEF and diabetes are poor prognostic markers. VT/VF patients undergoing CABG had double the predicted Parsonnet and four times the predicted EuroSCORE mortality rates, suggesting that preceding VT/VF is an important additional risk factor. Relative risk calculations of meta-analysis of ICD trials applied to the registry suggest between 7 to 12 ICDs will need to be implanted per annum to save one life. The registry also demonstrated that 79% of deaths of these SCD survivors occurred in-hospital and less than 15% of these deaths were classed as being arrhythmic.