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Value of latent outflow obstruction to predict clinical course of patients with hypertrophic cardiomyopathy

Objective The frequency, significance and prognostic value of left ventricle obstruction (LVO) induced with provocation (latent LVO) is controversial for hypertrophic cardiomyopathy (HC) patients. This study was designed to assess the value of latent LVO in predicting the clinical course in 101 patients with HC. Methods and results Patients were followed for a mean of 82 ± 48 months (range 2 to 148 months) for clinical end points defined as a composite of cardiovascular death resuscitated cardiac arrest, appropriate defibrillator shock or hospitalization due to worsening of heart failure symptoms. Presence of LVO (hazard ratio 3.63; 95% confidence interval, 1.85 to 7.12; P = 0.0001) and log NT-proBNP levels (hazard ratio, 1.40; 95% confidence interval, 1.14 to 1.72; P = 0.001) were the independent variables associated with an increased risk of experiencing clinical end points. HC patients with latent LVO have a trend toward decreased survival when compared with HC patients without LVO (log rank P = 0.027), but better survival than patients with resting LVO (log rank P = 0.007). HC patients with NT-proBNP levels <1,000 pg/ml had also better survival. LVO and NT-proBNP levels are the major determinants of clinical end points in patients with HC. Conclusions Evaluation of patients without resting LVO to demonstrate latent obstruction is of critical importance in respect of outcome and selection of patients for septal reduction therapies, so routine provocative testing with physiological exercise and measurement of NT-proBNP is recommended in this patient population for risk stratification.