Abstract 3599: Long-Term Prognosis in patients with Mid-Cavity Obstructive Hypertrophic Cardiomyopathy
It is of clinical importance to distinguish between the obstructive and non-obstructive forms of Hypertrophic Cardiomyopathy (HCM), based on the presence or absence of a left ventricular outflow tract pressure-gradient (LVOT-PG). Recently, management strategies and prognosis in outflow-tract obstructive HCM have been evaluated. However, diagnostic criteria, clinical profiles, and prognosis in patients (pts) with mid-cavity obstructive HCM (MO-HCM) remain unclear. Therefore, the purpose of this study was to describe prevalence and long-term prognosis in pts with MO-HCM.
Methods: A retrospective study of 455 pts with HCM (mean age at diagnosis was 43±16 years), who were diagnosed and followed-up in our hospital, was analyzed. MO-HCM was defined as having PG > 30mmHg across the LV mid-cavity, measured by under basal condition at echocardiography. Exclusion criteria were presence of LVOT-PG > 30mmHg at rest. We analyzed the prevalence, clinical profiles, HCM-related morbidity (stroke, syncope, or heart failure), HCM-related mortality (stroke related death, heart failure related death, or sudden death), and a probability of sudden death (sudden cardiac death, non-fatal cardiac arrest, or appropriate ICD interventions) in pts with MO-HCM during a mean follow-up of 8.5±6.0 years.
Results: In 455 pts with HCM, 45 pts were diagnosed as MO-HCM (mean age at diagnosis was 53±14 years, 26 males, mean PG across the LV mid-cavity = 46±16mmHg) during a mean follow-up of 8.5 years, corresponding to a prevalence of 10%. In these 45 pts, the incidence of familial HCM and familial history of sudden death were 16% and 11%, respectively. During a 9 year follow-up period, the probability of stroke, syncope, and heart failure were 3 pts (7%), 14 pts (31%), and 3 patient (7%), respectively. Furthermore, although no patients had stroke or heart failure related death, sudden death occurred in 6 of 45 pts (13%). Among these 6 pts, 3 pts had non-fatal cardiac arrest, 2 pts had appropriate ICD intervention, and 1 patient had sudden cardiac death.
Conclusions: This study demonstrates that MO-HCM is responsible for syncope and shows a high probability of sudden death. These results suggested that an aggressive prevention for sudden death should be considered in patients with MO-HCM.