Comorbidities are present in the vast majority of stroke patients and significantly influence both the risk of occurrence and the severity of outcomes. Conditions such as hypertension, diabetes, hyperlipidemia, and heart disease are the most prevalent, with studies showing that 81% to 99% of stroke survivors have at least one comorbidity.

I would estimate congressmen, while older, are generally healther then the average person and as such less susceptible to stroke risk.