Objectives: The pathophysiology of midventricular obstructive hypertrophic cardiomyopathy (MVO) is unknown. Patients with MVO and MVO-like cardiomyopathy were classified into three groups based on the cardioimaging morphological characteristics of the left ventricle to investigate their complications and treatment.
Methods: Four patients with MVO and one patient with disease-like MVO were admitted in our hospital from 1999 to 2005. Group A consisted of one patient with indications of pressure gradient at mid-ventricle without apical aneurysm, Group B consisted of three patients with indications of pressure gradient and apical aneurysm, and Group C consisted of one patient with hour-glass appearance with apical aneurysm and decreased left ventricular systolic function without pressure gradient.
Results: The diagnosis was established during examination for sustained ventricular tachycardia (SVT, three patients), paroxysmal atrial fibrillation (one patient), and coronary artery disease (one patient). Cardiogenic embolization was observed in all cases which originated from atrial fibrillation (one case) and apical aneurysm (two cases). No embolic event occurred in any patient after warfarin therapy. SVT occurred in patients in Groups B and C. SVT refractory to beta-blocker and mexiletine was treated by amiodarone. Apical aneurysmectomy and cryoablation could prevent recurrent SVT with drug resistance.
Conclusions: Four of the five patients with MVO had arrhythmia (atrial fibrillation, SVT) and three had cardiogenic embolization. MVO could be classified into three groups depending on the morphological characteristics and complications. Treatment of MVO should be based on these characteristics.