title: Adverse effects of atrial fibrillation and syncope induced by calcium-channel blockers in hypertrophic cardiomyopathy.
abstract: Calcium-channel blockers are useful for the treatment of hypertrophic cardiomyopathy (HCM), but, their adverse effects, especially, those of diltiazem, have not been of much concern. Forty patients with HCM were treated with calcium-channel blockers such as nifedipine, diltiazem, and verapamil. Atrial fibrillation was induced by diltiazem in two patients and verapamil induced syncope in one patient. The clinical and hemodynamic characteristics of the patients were as follows. All of them had the obstructive type of HCM (HOCM). One of them had a high pressure gradient of the left ventricular outflow tract and the others had earlier onset. In these patients, the left atrial overload seemed to be severe. The vasodilating action of calcium-channel blockers decreases the systemic pressure and in turn, may increase the pressure gradient and the left ventricular end-diastolic pressure. The elevated left ventricular end-diastolic pressure causes the left atrial overload which could be at risk of atrial fibrillation in patients with HCM. Therefore, calcium-channel blockers should be used carefully in peculiar cases of HOCM.
mesh_terms: D000328:Adult; D001281:Atrial Fibrillation / Q000139:chemically induced*; D001552:Benzazepines / Q000009:adverse effects*; D002312:Cardiomyopathy, Hypertrophic / Q000188:drug therapy*; D004110:Diltiazem / Q000009:adverse effects* / Q000627:therapeutic use; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011433:Propranolol / Q000627:therapeutic use; D013575:Syncope / Q000139:chemically induced*; D014700:Verapamil / Q000009:adverse effects* / Q000627:therapeutic use
chemical_list: D001552:Benzazepines; D011433:Propranolol; D014700:Verapamil; D004110:Diltiazem