Heart attacks were unheard of before about 1910, so they can't be caused by traditional animal foods
Heart attacks were not missing before 1910. The diagnosis was. The condition was first described clinically in 1912, so earlier deaths were recorded under other names, and heart disease was already one of the leading causes of death in America in 1900.
Heart attacks went from rarely recorded to the leading cause of death within a few decades of the early twentieth century. That is the same period in which industrial seed oils, refined sugar and processed food entered the diet, while people had been eating meat and animal fat for thousands of years. If animal foods were the main driver of heart disease, the epidemic should not have arrived so suddenly and so late, so blaming meat appears to get the timeline backwards.
The absence of records reflects a missing diagnosis, not a missing disease. The American physician James Herrick published the first clear clinical description of a heart attack caused by a blocked coronary artery in 1912. Before that, doctors had no agreed way to recognise one in a living patient. Deaths that would now be recorded as myocardial infarction were written down as 'acute indigestion', 'apoplexy', 'heart failure' or simply sudden death. A cause of death nobody was diagnosing cannot show up in the records as that cause.
The broader category was already common. In 1900, 'diseases of the heart' ranked fourth among causes of death in the United States, behind pneumonia, tuberculosis and gut infections. Angina had been described in the 1760s, and coronary thrombosis had been found at autopsy during the 1800s.
The recorded rise after 1910 has several real causes. Doctors learned to diagnose it. Fewer people died young of infections, so more lived to the ages when heart attacks happen. Cigarette smoking spread rapidly over the same decades. Diet may well have played a part too, but a timeline cannot separate these causes from each other.
The underlying disease is also much older than modern diets. CT scans of 137 mummies from four ancient populations, including Aleutian hunter-gatherers, found probable or definite atherosclerosis in about a third of them. Arteries were clogging long before seed oils or refined sugar existed.
What foods raise heart risk today is settled by trials and long-running cohort studies, not by what death certificates in 1905 did or did not say. And neither the history nor the nutrition decides the ethical question, which concerns what is done to the animals.
Treating the absence of proof against a claim as proof of it, or the absence of proof for a claim as proof against it.
How it applies here: The claim treats the lack of documented heart attack deaths before 1910 as proof that heart attacks did not happen. But the condition had not yet been clinically described, so no such records could exist whether or not people were dying of it.