Could a switch from Fresh Pet to Science Diet kibble cause a dog in CHF suddenly die?

My dog had been eating Fresh Pet for a several years, the chicken or beef (not the grain free.) Two weeks ago I started switching her over to Hills Science Diet Adult Small Bites. At first I mixed the two 50/50 and gradually to 75% kibble and 25% Fresh Pet. She also started doxycycline and had about 4 days of doses and then suddenly died in her sleep.

We had no idea she had heart disease. The necropsy revealed enlarged heart and severely thickened left ventricle.

Now I am worried that the switching of her food could have caused her sudden death. Could switching to mainly kibble cause a dog experiencing CHF to suddenly succumb to the disease and die? Could the new food have dramatically increased her sodium intake = more fluid retention = more workload on the heart? She was extra thirsty in the last few days of her life. Could the reduced moisture intake from the food have caused this?

I’m trying to understand how this happened.