Introduction National and international guidelines recommend an implantable cardioverter defibrillator (ICD) for primary prevention of sudden cardiac death, in patients in NYHA Class I-III and with left ventricular ejection fraction ≤35% of either ischaemic or non-ischaemic aetiology and reasonable survival. At times, selection of appropriate patients can be challenging, calling on clinicians to balance the probability of death due to ventricular tachycardia/ventricular fibrillation (VT/VF) versus the competing risk of non-arrhythmic mortality (NAM). The validated MADIT-ICD Benefit Prediction Score (MIBPS), based on 15 clinical and technical variables, has been proposed as an objective decision-making tool to help clinicians in difficult cases. Complex devices at our centre are implanted after a multidisciplinary discussion. We therefore applied this score retrospectively to our patients with complex devices to assess its utility.
Methods N=280 new complex device implants between 2014-2017. Review of records, including device downloads, yielded 103 patients suitable for inclusion. Calculation of VT/VF Risk Score (ARS) and NAM Risk Score (NAMRS), followed by assignment of a MADIT-ICD Benefit Group (BG) [High (high ARS and low NAMRS), Intermediate (low ARS and low NAMRS, or high ARS and high NAMRS) or Low (low ARS and high NAMRS)]. On follow-up, primary outcomes identified were: occurrence of VT/VF post implant or NAM prior to any VT/VF episode.
Results (Table 1A) Whole cohort: Age: 64 ± 11, , (35-89); Female: 27/103 (26.2%); CRT-D: 35 (34%); Diabetes: 24 (23.3%); Atrial Arrhythmia: 22 (21.4%); Previous Myocardial Infarction: 68 (66%); NSVT: 22 (21.4%). At baseline, significant majority were in the Highest or Intermediate BG. On follow-up, the same BG’s had a majority of VT/VF events. Moreover, the proportion of VT/VF within each BG corresponded to the grade of benefit: Highest (22.6%), Intermediate (19.7%), Lowest (9.1%). The distribution of NAM was less well defined, and spanned across all BG’s, with the majority occurring in the Intermediate BG. No significant differences among the BG’s were seen in for patients with no events.
Conclusion In our experience, over the medium term (~5 years), the MIBPS was best able to suggest candidates with a high (High BG) or a low (Low BG) likelihood of benefit from a primary prevention ICD. It was not able to as clearly define those likely to suffer NAM, irrespective of the BG. Likely better tools are required to determine the benefit of an ICD in the Intermediate BG.
Conflict of Interest Nil
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