Major risk factors:
(1) cardiac arrest associated with ventricular fibrillation
(2) spontaneous sustained ventricular tachycardia
(3) family history of all of the following:
(3a) sudden death secondary to hypertrophic obstructive cardiomyopathy
(3b) in >= 2 first degree relatives
(3c) who are < 40 years of age.
Minor risk factors:
(1) >= 2 episodes of unexplained syncope within 1 year
(2) left ventricular wall thickness > 30 mm
(3) abnormal blood pressure during exercise with either (a) failure of blood pressure to rise > 25 mm Hg above baseline or (b) decrease by > 10 mm from the maximal blood pressure during exercise in an upright position
(4) nonsustained ventricular tachycardia demonstrated on Holter monitor or during exercise, with (a) >= 3 consecutive ventricular extrasystoles (b) with the heart rate > 120 beats per minute and (c) with duration < 30 seconds
(5) left ventricular outflow obstruction
(6) microvascular obstruction (perfusion defects on nuclear imaging or magnetic resonance imaging)
(7) high-risk genetic defect (mutations in the genes encoding the sarcoplasmic proteins)
High risk for sudden death is defined as one of the following:
(1) 1 or more major risk factors
(2) 3 or more minor risk factors
A patient at high risk for sudden death is a candidate for prophylactic implantation of an automatic defibrillator.
