Comparison of two European models estimating risk of sudden cardiac death in hypertrophic cardiomyopathy

Objective Hypertrophic cardiomyopathy (HCM) is associated with a risk of sudden cardiac death (SCD). Several models have been developed to estimate SCD risk and guide preventive therapy. The comparison of the previous 2003 with novel 2014 SCD risk models have never been studied. Methods Over a year we included 103 consecutive HCM patients without previous cardiac arrest and/or ICD implanted (65% males; aged 53.3 ± 13.9 years; mean EF 62.3 ± 18%). The SCD risk was calculated for each patient. Results Based on the 2003 model, patients had following scores: 0 points -15 (15%) patients, 1-28 (27%), 2-34 (33%), 3-18 (17%), ≥ 4-8 (8%). According to the 2014 model 83 (80%) had low risk, 12 (12%) intermediate risk, and only 8 (8%) high risk. Patients who had an intermediate or high risk in the 2003 model but a low risk in 2014 model were the oldest, experienced less frequently syncope and nsVT, but had more often abnormal blood pressure response to exercise and an intermediate LVOT gradient in comparison to the patients who had consistently low or high risk in both models. Conclusions Calculation of SCD risk using two models provides completely different risk estimates and consequently different guidance on SCD primary prevention. According to the 2003 model up to 85% of patients have indications for ICD, whereas based on the 2014 risk model only 20% of the patients had non-negligible SCD risk and are candidates for ICD therapy. SCD risk markers, used in the 2003 and 2014 models, have various discriminating power.