Abstract 16105: Significance of Asymptomatic Ventricular Tachycardia Observed During Pacemaker Clinic Interrogations
Modern pacemakers chronicle a variety of arrhythmias over time. Asymptomatic ventricular tachycardia (VT) is observed in this setting, but its frequency, significance, and treatment are unclear. The Lown classification of ventricular arrhythmias attached a poor prognosis to VT, including a high incidence of sudden death and sustained symptomatic arrhythmias. We compared our asymptomatic pacemaker clinic population with VT to similar pacemaker patients without VT to determine risk of death and arrhythmic associations. Pacemaker clinic records from our tertiary referral center were retrospectively reviewed for the occurrence of VT in asymptomatic patients. VT was defined as 3 or more consecutive VPC's at a rate of at least 150 beats per minute (bpm). Records from 1996-2010 were screened, and a total of 1071 patients were identified with suitable recordings. This population was characterized as follows: age 76 ± 12, males 52%, EF 61±13%, LVH 37%, treated coronary disease 34%, and diabetes 16%. The indications for pacemaker implant were complete heart block (30%) and sick sinus syndrome (78%). Atrial fibrillation was present in 56%. Anti-arrhythmic drugs were used in 21%, and beta-blockers in 41%. Follow up was 4±3 years. VT was seen in 155 (14%) patients: 96 males (62%), and 59 females (38%). VT duration was 4-29 beats, with mean duration 9.5 ± 4 beats. 70% of patients with VT had duration of 10 beats or less. Heart rate during VT averaged 181 ± 30 bpm. During follow-up, 156 (14%) patients died. Death was not associated with VT occurrence, VT cycle length, or VT duration. Death was strongly associated with low EF, and with valvular heart disease. However, valvular heart disease was not associated with VT. A significant incidence of VT was seen in this study. Subjects with VT did not have a worse prognosis, compared to patients without VT. VT rate and duration did not predict subpopulations at increased risk. The difference in the prognosis of VT from previous studies of patients with other disease entities is probably related to differences in subject population substrates and underlying arrhythmia mechanisms. The dominant pathophysiology in our study population was sick sinus syndrome.
- © 2011 by American Heart Association, Inc.