Background Implantable cardiac defibrillator (ICD) therapy reduces mortality in selected patients at high risk of sudden cardiac death. However, patients at high risk of non-sudden cardiac death, whose risk of short-term mortality following device implantation is high, may gain no significant benefit from an ICD. A number of approaches have been proposed to identify these high-risk patients, including single clinical markers and more complex scoring systems. The aims of this study were to use the proposed scoring systems to: (1) establish how many current ICD recipients may be too high risk to derive significant benefit from ICD therapy and (2) evaluate how well the proposed scoring systems predict short-term mortality in an unselected cohort of ICD recipients.
Methods We performed asingle-centre retrospective observational study of all new ICD implants over 5years (2009–2013). We used 3 published scoring systems (Kramer et al 1; Barsheshet et al 2; Parkash et al 3) to identify new ICDrecipients whose short-term risk of death following ICD implantation waspredicted to be high. We then evaluated how well the scoring systems predicteddeath during follow-up.
Results Over 5 years there were 406 new implants (79% male, age 67 ± 13 years). The majority (58%) were primary prevention implants and 45% were cardiac resynchronisation therapy-defibrillator devices. During a mean follow-up of 936 ± 560 days, 77 patients died.
Using the published scoring systems, the proportion of ICD recipients predicted to be at high risk of short-term mortality were 4% (Kramer), 36% (Barsheshet) and 23% (Parkash). Three-year mortality rates in these high-risk groups were 76%, 32% and 36% respectively; in the overall study population 3-year mortality was 20%.
In univariate Cox regression analyses, all 3 scoring systems predicted death (p < 0.001 for each model). However, using multivariate analysis, only the Kramer model remained predictive once serum urea was included in the analysis (p < 0.001). The ROC scores for the prediction of death for the 3 scoring systems and urea were 0.73 (Kramer), 0.69 (Barsheshet), 0.65 (Parkash) and 0.70 (urea).
Conclusions Using published scoring systems, a significant proportion of current ICD recipients are at high risk of short-term mortality following device implantation. Although all 3 scoring systems predicted mortality during follow-up, only the Kramer model added predictive accuracy compared to renal function alone.
Kramer DB, Friedman PA, Kallinen LM, Morrison TB, Crusan DJ, Hodge DO, Reynolds MR, Hauser RG. Development and validation of a risk score to predict early mortality in recipients of implantable cardioverter-defibrillators. Heart Rhythm 2012;9:42–6
Barsheshet A, Moss AJ, Huang DT, McNitt S, Zareba W, Goldenberg I. Applicability of a risk score for prediction of the long-term (8-year) benefit of the implantable cardioverter-defibrillator. J Am Coll Cardiol 2012;59:2075–9
Parkash R, Stevenson WG, Epstein LM, Maisel WH. Predicting early mortality after implantable defibrillator implantation: a clinical risk score for optimal patient selection. Am Heart J 2006;151:397–403
- ICD therapy
- scoring system
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