Background Hypertrophic cardiomyopathy (HCM) is characterized by increased left ventricular (LV) stiffness, leading to raised ventricular filling pressures and restrictive diastolic dysfunction (RDD), in itself independently associated with an increased risk of a clinical deterioration. We assessed whether echocardiography evaluation of diastolic function in HCM could yield prognostic value and be useful in HCM risk stratification. Methods We retrospectively reviewed clinical and imaging (echocardiography and cardiovascular magnetic resonance, CMR) data from 361 consecutive patients from two HCM Italian referral centers (Mauriziano Hospital, Turin; University Hospital of Trieste, Trieste). Among them, 28 patients were classified after Doppler echocardiography examination as restrictive (E/A > 1.5, DecT E < 140 ms, E/e’ > 10). The primary endpoint was a large cardiovascular composite consisting of sudden cardiac death (SCD), major ventricular arrythmias (MVAs), heart transplant (HT) and hospitalization for heart failure (HF). Other secondary endpoints were investigated as follows: 1) a secondary arrhythmic endpoint consisting of SCD and MVAs, 2) a key secondary composite of HF, HT, non–SCD. A Bayesian Model Averaging (BMA) was then performed to overcome the bias determined by the limited number of observations. Results Over a mean follow up of 7 ± 3 years, 61 (17%) patients experienced at least one primary composite endpoint event. Of them, 10 were identified with a restrictive diastolic pattern. When BMA was performed, late gadolinium enhancement (LGE) presence at CMR and RDD were significantly associated with the primary composite outcome (respectively, PI = 100, HR = 3.55, pd = 1.00; PI = 74.5, HR = 3.33, pd = 0.99). Left atrium (LA) diameter was not strongly associated with the arrhythmic endpoint, whereas it was significantly associated with the key secondary composite outcome, as well as with increased filling pressures (E/e’) (respectively, PI = 94.5, HR = 1.10, pd = 1.00; PI = 86.8, HR = 1.08, pd = 0.99). Conclusions Restrictive diastolic dysfunction is an independent predictor of poor prognosis in early stages of HCM in absence of systolic dysfunction. In particular, RDD predicted outcomes related to heart failure better then LA diameter and E/e’.

Background To date, the prognostic impact of transcatheter ablation (T–Abl) of supraventricular arrhythmias (SA) in HCM patients has not been satisfactorily elucidated. Objectives To assess the impact of T–Abl on clinical outcomes in a large cohort of HCM patients. Methods In this retrospective multicenter study, 570 consecutive HCM patients with SA were enrolled, 425 receiving medical therapy and 145 undergoing T–Abl. 1:1 propensity score matching (PSM) led to the inclusion of 234 patients (117 intervention group, 117 medical group) in the final analysis for endpoint evaluation. The primary outcome was a composite of all–cause mortality, heart transplantation (HT) and worsening heart failure (HF). Additionally, an inverse probability weighted (IPW) model was elaborated. Results At PSM analysis, after a median follow-up of 57.3 months, the primary endpoint occurred in 31 (26.5%) patients in the intervention group vs 38 (32.5%) in the medical group (p=0.871). Thromboembolic strokes and major arrhythmic events in the intervention vs the medical group were 9.4% vs 9.4% (p=0.367) and 5.1 vs 7.7% (p=0.741), respectively. Fewer patients in the intervention vs medical group experienced SA recurrences (64.1% vs 84.6%, p<0.001) and transition to permanent SA patterns (21.4% vs 37.6%, p=0.007). IPW analysis showed consistent results. Severe complications related to T–Abl were uncommon (0.7%). Conclusions At 5–year follow–up, T–Abl does not improve major clinical outcomes in a large cohort of HCM patients. Nevertheless, T–Abl seems to facilitate the maintenance of sinus rhythm and decelerate the progression to permanent SA. Lastly, T–Abl is usually safe in HCM.