Hypertrophic cardiomyopathy in childhood and adolescence - strategies to prevent sudden death.
Clinically overt hypertrophic cardiomyopathy is the most common cause of sudden unexpected death in childhood and has significantly higher sudden death mortality in the 8- to 16-year age range than in the 17- to 30-year age range. A combination of electrocardiographic risk factors (a limb-lead ECG voltage sum >10 mV) and/or a septal wall thickness >190% of upper limit of normal for age (z-score > 3.72) defines a paediatric high-risk patient with great sensitivity. Syncope, blunted blood pressure response to exercise, non-sustained ventricular tachycardia and a malignant family history are additional risk factors. Of the medical treatments used, only beta-blocker therapy with lipophilic beta-blockers (i.e. propranolol, metoprolol or bisoprolol) have been shown to significantly reduce risk of sudden death, with doses ≥ 6 mg/kg BW in propranolol equivalents giving around a tenfold reduction in risk. Disopyramide therapy is a very useful adjunct to beta-blockers to improve prognosis in those patients that have dynamic outflow obstruction in spite of large doses of beta-blocker, and its use in patients with hypertrophic cardiomyopathy is not associated with significant pro-arrhythmia mortality. Calcium-channel blockers increase the risk of heart failure-associated death in hypertrophic cardiomyopathy (HCM) patients with severe generalized hypertrophy and should be avoided in such patients. Amiodarone does not protect against sudden death, and long-term use in children usually has to be terminated because of side effects. Therapy with internal cardioverter defibrillator implantation has high paediatric morbidity, 27% incidence of inappropriate shocks, and does not absolutely protect against mortality but is indicated as secondary prevention or in very high-risk patients.
Ostman-Smith
Ingegerd
I
Division of Paediatric Cardiology, Institute of Clinical Sciences, Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden. ingegerd.ostman-smith@pediat.gu.se
D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000009:adverse effects / Q000627:therapeutic use*; D000328:Adult; D000367:Age Factors; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects / Q000627:therapeutic use; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications* / Q000628:therapy; D002648:Child; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D006801:Humans; D012307:Risk Factors; D055815:Young Adult
D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents