Regional myocardial ischemia in hypertrophic cardiomyopathy: impact of myectomy.

OBJECTIVE: Chest pain is a common finding in patients with hypertrophic cardiomyopathy and can be observed in 40% to 50% of all patients. However, the pathogenesis of these ischemia-like symptoms is still unclear.
METHODS: Twenty-two patients with hypertrophic cardiomyopathy and 15 controls underwent positron emission tomography for evaluation of regional myocardial perfusion and coronary flow reserve (hyperemic/baseline myocardial blood flow). Myocardial perfusion (mL/min/g) was measured using [(13)N]ammonia at rest and during hyperemia with dipyridamole (0.56 mg/kg intravenously). Regional coronary flow reserve was assessed in 3 planes (apical, midventricular, basal) in 4 regions (septal, anterior, lateral, inferior). Patients were divided into 2 groups: group 1 consisted of 11 patients treated with surgical myectomy (age 56 +/- 10 years) and group 2 consisted of 11 patients treated medically (age 53 +/- 13 years).
RESULTS: Mean global coronary flow reserve was 3.87 +/- 0.92 in controls but 2.31 +/- 0.40 in operated (P <.001 vs controls) and 1.76 +/- 0.58 in medically treated patients (P <.001 vs controls, P <.05 vs operated). Similarly, septal coronary flow reserve was 4.19 +/- 1.22 in controls but significantly reduced in operated patients (2.26 +/- 0.48, P <.001 vs controls) and in medically treated patients (1.76 +/- 0.58; P <.001 vs controls). However, septal flow reserve was significantly higher in operated patients than in patients with medically treated hypertrophic cardiomyopathy (+37%, P <.05), mainly due to a reduced resting myocardial perfusion.
CONCLUSIONS: Global and regional myocardial perfusion is reduced in patients with hypertrophic cardiomyopathy. However, myectomy may have a beneficial effect on septal perfusion and flow reserve. Thus, ischemia seems to play an important role in the symptomatology and pathophysiology of hypertrophic cardiomyopathy.