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It is unclear whether the electrocardiogram (ECG) can provide prognostic information regarding the likelihood of sudden (SCD) versus cardiac non sudden death (C/NS) in high risk cardiac patients. Accordingly, we sought to evaluate the prognostic value of resting and ambulatory ECG parameters in patients with ischemic cardiomyopathy who were eligible for the primary prevention of SCD with an implantable cardioverter-defibrillator (ICD).
We prospectively evaluated 17 well validated high risk ECG parameters in PAREPET subjects (Prediction of ARrhythmic Events with Positron Emission Tomography; n = 204, EF ≤ 35%, age 67 ± 11 years, 90% men). Twenty-four hour holter ECG recordings were obtained in 97% of patients at start of study and were semi-automatically evaluated by a blinded reviewer. Patients were followed up by phone at 3-months intervals. Endpoints were determined by a blinded committee of cardiologists. ICD discharges due to ventricular fibrillation or tachycardia (>240 beats/min) were considered equivalent to SCD.
After a mean follow up of 51+2 months, there were 33 (16%) SCD and 36 (18%) C/NS. In the multivariate analysis, QTc prolongation was predictive of SCD (hazard ratio 2.9 [1.2-7.3]) and depressed heart rate variability (HRV) was predictive of C/NS (hazard ratio 5.0 [1.5-17.1]). Persistent bi-ventricular pacing was associated with increased C/NS mortality, probably due to the strong correlation with a lower LVEF.
Among candidates for primary prevention of SCD, the ECG can yield further prognostic information independently from age and LVEF. Prolonged QTc predicted SCD and therefore potential ICD benefit. On the other hand, depressed HRV predicted C/NS death, suggesting that this risk factor may be particularly helpful to identify those who might benefit from bi-ventricular pacing in order to reduce the risk of heart failure death.
Poster Sessions, Expo North
Saturday, March 09, 2013, 10:00 a.m.-10:45 a.m.
Session Title: New Diagnostic and Imaging Strategies in Heart Failure
Abstract Category: 15. Heart Failure: Clinical
Presentation Number: 1136-311
- 2013 American College of Cardiology Foundation