The mechanism seems to be an abnormality in vascular tone. Despite all the studies that have been done to accurately identify individuals at risk of sudden cardiac death, the phenotypic evidence seems to have come up short. IHSS is not a single disease entity, but rather represents a group of diseases. The spectrum of IHSS ranges from a subclinical form to a very lethal form. Future investigations to identify those at high risk are being directed at genetic testing.
Some mutations appear to be more benign than others.
Treatment Treatment of IHSS is aimed at reducing the contractility of the myocardium and suppressing life-threatening arrhythmias. Verapamil has become the drug of choice for symptomatic IHSS because of its beneficial effects on systolic and diastolic left ventricular function. Therefore, individuals susceptible to ventricular arrhythmias are placed on antiarrhythmics. The cardiology panel at the FAA Aeromedical Certification Division thoroughly reviewed this airman's case for consideration of a special issuance first-class medical certificate. After reviewing the history and all pertinent cardiac evaluations performed on the airman, they determined that IHSS puts this airman in a high-risk category for sudden incapacitation.