Abstract 1750: Coronary Microvascular Dysfunction and Prognosis in Hypertrophic Cardiomyopathy: a Doppler Echocardiography Study
Background. Microvascular dysfunction, reflected by an inadequate increase in myocardial blood flow in response to dipyridamole infusion, is a recognized feature of hypertrophic cardiomyopathy (HCM) and may have prognostic impact. Coronary flow reserve (CFR) can be assessed on left anterior descending coronary artery (LAD) with Doppler 2D-echocardiography. Aim. To prospectively evaluate a cohort of patients with HCM after they had undergone quantitative assessment of CFR on LAD with ultrasound.
Methods. 68 patients (New York Heart Association class I or II) with HCM were followed for a mean (± SD) of 22±13 months after dipyridamole (0.84 mg/kg over 6′)-Doppler echocardiography.
Results. CFR on LAD was normal (>2.0) in 37 and abnormal (<2.0) in 31 patients. Twenty seven events occurred during follow-up: 1sudden death, 1 non-fatal myocardial infarction, 4 cardioverter-defibrillator implantations, 6 re-hospitalizations for heart failure, 2 syncopes, 5 unstable angina and 8 atrial fibrillations. The 36-month event-free survival was 17% in patients with normal and 79% in patients with abnormal CFR (Figure⇓). With a Cox analysis, abnormal CFR on LAD (HR=2.53; 95% CI=1.1–5.7), history of syncope (HR=4.7; 95% CI=1.6–13.7), rest LV obstruction (HR=2.7; 95% CI=1.1– 6.4), and abnormal CFR on LAD (HR=4.3; 95% CI=1.3–13.8) were independent prognostic predictors.
Conclusions. In patients with HCM, the ultrasound-based assessment of the degree of microvascular dysfunction is a strong, independent predictor of clinical deterioration. Severe microvascular dysfunction is often present in patients with mild or no symptoms and may precede clinical deterioration by years.