Probability SCD at 5 years= 1 – 0.998exp(prognostic index)
where prognostic Index= 0.15939858*Maximal wall thickness (mm)-0.00294271*Maximal wall thickness2 (mm2)+0.0259082*Left atrial diameter (mm)+0.00446131*Maximal (rest/Valsalva) left ventricular outflow tract gradient (mmHg)+0.4583082*Family history SCD+0.82639195*NSVT+0.71650361* Unexplained syncope -0.01799934*Age at clinical evaluation (years).
HCM Risk-SCD should not be used in:
Pediatric patients (<16 years)
Elite/competitive athletes
HCM associated with metabolic diseases (e.g. Anderson-Fabry disease), and syndromes (e.g. Noonan syndrome).
Patients with a previous history of aborted SCD or sustained ventricular arrhythmia who should be treated with an ICD for secondary prevention.
Caution should be exercised when assessing the SCD in patients following invasive reduction in left ventricular outflow tract obstruction with myectomy or alcohol septal ablation.
** ICD not recommended unless there other clinical features that are of potential prognostic importance and when the likely benefit is greater than the lifelong risk of complications and the impact of an ICD on lifestyle, socioeconomic status and psychological health.
1 Age at evaluation - years
2 TTE measurement - mm
3 Left atrial diameter determined by M-Mode or 2D echocardiography in the parasternal long axis plane at time of evaluation
4 The maximum LV outflow gradient determined at rest and with Valsalva provocation (irrespective of concurrent medical treatment) using pulsed and continuous wave Doppler from the apical three and five chamber views. Peak outflow tract gradients were determined using the modified Bernouilli equation: Gradient= 4V2, where V is the peak aortic outflow velocity
5 History of sudden cardiac death in 1 or more first degree relatives under 40 years of age or SCD in a first degree relative with confirmed HCM at any age (post or ante-mortem diagnosis).
6 =3 consecutive ventricular beats at a rate of =120 beats per minute and <30s in duration on Holter monitoring (minimum duration 24 hours) at or prior to evaluation.
7 History of unexplained syncope at or prior to evaluation.
HCM = hypertrophic cardiomyopathy;
LV = left ventricular;
LVOT = left ventricular outflow tract;
NSVT = non-sustained ventricular tachycardia;
SCD = sudden cardiac death;
VT = ventricular tachycardia
