Incident cases were also followed for specific diagnostic and therapeutic procedures. This was accomplished by record review and by matching lists of case patient numbers with identification numbers of patients who underwent the following: radionuclide ejection fractions and radionuclide exercise tests beginning in 1980; arteriography, ventriculography, valve evaluation, thrombolytic infusion, percutaneous transluminal coronary angioplasty or balloon angioplasty, and electrophysiologic testing beginning in 1976; coronary artery bypass surgery, myocardial resection, and valve repair or replacement beginning in 1978; coronary intensive care unit data beginning in 1976. New procedures were monitored as they came into use.