Therapeutical Approaches for HCM Are Symptom Oriented

p-Blockers act as negative inotropic drugs and are used as first-line drugs in patients with or without LV obstruction, and are the preferred treatment in symptomatic HCM patients with an LV outflow tract gradient only by exertion.[5] Verapamil, a calcium antagonist with negative inotropic properties, is used in both obstructive and nonobstructive forms in patients without severely disabling symptoms. Disopyramide, a class IA antiarrhyth-mic drug with negative inotropic effects, is reserved for patients with outflow tract obstruction not responding to p-blocker and verapamil. End-stage HCM requires adapted therapy including angiotensin-converting enzyme (ACE) inhibitors or angiotensinogen II receptor blockers, diuretics, spironolactone, and digitalis.

Septal myectomy can abolish the gradient caused by severe outflow tract obstruction. Alcohol septal ablation initiates controlled septal myocardial infarction to reduce the gradient. Dual-chamber pacing allows substantial reduction of the gradient and more aggressive medical treatment. Patients at high risk for SCD with important outflow tract gradient benefit from biventricular pacing properties of an implantable cardioverter defibrillator.

Risk stratification for SCD in HCM patients is currently based on available clinical data, but does not yet allow to precisely identify all patients at high risk.[6]

a-cardiac actin (a-cAct), TNNT2, TNNI3, and TNNC1 for the cardiac troponins T, I, and C (cTnT, cTnl, and cTnC), and TPM1 for a-tropomyosin (a-TM). MYBPC3 encodes the cardiac myosin-binding protein C (cMyBP-C), TTN encodes titin, and CRP3 encodes the muscle LIM protein (MLP), which is a Z-disc protein stabilizing the contractile apparatus. Recently, a mutation in the promoter region of the phospholamban gene (PLN) has been reported.[8] Patients presenting FHC associated with the Wolff-Parkinson-White syndrome plus ventricular preexcitation exhibited mutations in PRKAG2, encoding the g2-regulatory subunit of AMP-activated protein kinase (AMPK), a metabolic protein.

Today, about 200 mutations in all these disease genes are known (http://www.angis.org.au/Databases/Heart/ heartbreak.html). Eighty percent of the genotyped families present a mutation in MYH7 and MYBPC3;[9] at least these two genes should be systematically screened for mutations in routine diagnostics.

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