If it is associated with swimming induced pulmonary edema mechanism is still somewhat of a ? but is believed to be more associated with the increased pulmonary pressure associated with exercise in combo with peripheral vasoconstriction in the elderly.

Combine this with an old, obese, likely degree of low LVEF and your lungs are set up to fail.

Guy probably had an MI. Pulmonary edema comes in a bunch of different flavors.