what caused sudden death in a congested heart failure with high blood pressure?

Answer 1

could have been a stroke from the bp

could have been the fluid build up

heart could have just given up, or had a major heart attack, killing too much of the muscle tissue

Answer 2

Congestive heart failure (CHF) with hypertension (high BP) is a precarious situation innately, with acute death depending on the underlying cause. Classic scenarios of sudden death in a CHF patient typically involve a pulmonary embolus, acute valve regurgitation, or massive MI, which are all very possible in a CHF patient

Answer 3

It can be a direct, last-stage result of heart damage from one or more of several heart or circulation diseases.
It can occur over time as the heart tries to compensate for abnormalities caused by these conditions, a condition called remodeling.
In all cases, the weaker pumping action of the heart means that less blood is sent to the kidneys. The kidneys respond by retaining water and salt. This in turn increases edema (fluid buildup) in the body, which causes widespread damage.

Answer 4

Practically speaking your question has only two reasons:
1) Pulmonary edema & bilateral pulmonary congestion.
2) Cardiac arrest./or acute massive myocardial Infarction.