PEOPLE MAGAZINE:
In a statement detailing autopsy results, Dr. Michael Newman said his famous patient had passed a stress test on April 29 and had even worked out on a treadmill the morning of his death.
"Russert, age 58, was known to have asymptomatic coronary
artery disease (atherosclerosis), which resulted in hardening of his coronary arteries," Newman said. "The autopsy revealed an enlarged heart and significant
atherosclerosis of the left anterior descending coronary artery with (a) fresh clot which caused a heart attack resulting in a fatal ventricular arrhythmia."