That sounds a lot like human heart failure. And a painful loss. I am so sorry.I had a dog who who was diagnosed with a heart murmur at 5. By 9 he had congestive heart failure. When he was 10, he was laying on the ground and his heart just stopped. Died on the spot.
Not sure if that's considered a heart attack, but it was definitely his heart that killed him.
I agree that a dog can suffer myocardial infraction. Again, blockage due to adult heartworm infestation... What else though?"Heart Attack" is not exactly a scientific term, so it would be open to discussion. Now if the question is if dogs can have Myocardial Infarction, the answer is yes.
Heart Attack in Dogs | petMD
Other than that, all mammals die when their hearts stop and the heart of all mammals stop when they die.