TABLE 3

Risk-stratification models for primary prevention of sudden cardiac death in hypertrophic cardiomyopathy

North American model	European model
An implantable cardioverter-defibrillator (ICD) is reasonable (class IIa recommendation, level of evidence C—limited evidence) if any of the following are present: Family history of sudden death Unexplained syncope Maximum left ventricular wall thickness ≥ 30 mm Or if the patient has any other risk factor or modifier for sudden cardiac death and either of the following: Nonsustained ventricular tachycardia Abnormal blood pressure response during exercise (decrease or failure to increase systolic blood pressure ≥ 20 mm Hg during exercise stress test)	The following factors are used to electronically calculate the 5-year risk of sudden cardiac death: Family history of sudden death Unexplained syncope Maximum left ventricular wall thickness Nonsustained ventricular tachycardia Age Left atrial diameter Left ventricular outflow gradient 5-year risk < 4%: an ICD is generally not indicated 5-year risk ≥ 4% to < 6%: an ICD may be considered 5-year risk ≥ 6%: an ICD should be considered

North American model

European model

An implantable cardioverter-defibrillator (ICD) is reasonable (class IIa recommendation, level of evidence C—limited evidence) if any of the following are present:

Family history of sudden death
Unexplained syncope
Maximum left ventricular wall thickness ≥ 30 mm

Or if the patient has any other risk factor or modifier for sudden cardiac death and either of the following:

Nonsustained ventricular tachycardia
Abnormal blood pressure response during exercise (decrease or failure to increase systolic blood pressure ≥ 20 mm Hg during exercise stress test)

The following factors are used to electronically calculate the 5-year risk of sudden cardiac death:

Family history of sudden death
Unexplained syncope
Maximum left ventricular wall thickness
Nonsustained ventricular tachycardia
Age
Left atrial diameter
Left ventricular outflow gradient

5-year risk < 4%: an ICD is generally not indicated
5-year risk ≥ 4% to < 6%: an ICD may be considered
5-year risk ≥ 6%: an ICD should be considered

Based on information in references 9 and 30.