The St. Francis Heart Study demonstrated that fast CT scanning of the coronary arteries predicts coronary events such as heart attack independently of and more accurately than conventional risk factors such as age, smoking, blood pressure and cholesterol, and C-reactive protein ( CRP ).

The study, conducted by researchers at St. Francis Hospital, The Heart Center, used fast computed tomography ( CT ) scanning to measure the calcium scores of 4,903 apparently healthy patients and followed the patients for 4.3 years. Fast CT scanning shows the amount of calcification in the coronary arteries, which is related to the severity of underlying coronary artery disease.

“As the largest, population-based study to date, the St. Francis Heart Study shows that CT scanning of coronary arteries can be used to refine the standard risk categories, known as the Framingham risk index,” said Alan D. Guerci, lead study author and at the St. Francis Hospital, The Heart Center, in Roslyn, New York. “ Our study creates a very strong argument for scanning all patients at intermediate risk according to the Framingham criteria.”

Approximately one-third of Americans ages 40-70 are at intermediate risk for coronary artery disease, as defined by the Framingham risk index, which calculates a patient's risk for a heart attack or stroke in the next 10 years based on factors such as age, cholesterol, hypertension, smoking and diabetes.

Heart disease is the leading cause of death for both men and women in the United States. More than 1.5 million heart attacks occur in the United States annually, resulting in up to 500,000 deaths each year. In up to 50 percent of all heart attacks, the heart attack itself is the first symptom of heart disease. Early detection and intervention is the single best way to improve the likelihood of effective treatment.

“Increasing the accuracy of risk stratification through the use of fast CT scanning provides a very direct benefit to patients. Many patients classified at intermediate risk with clear signs of underlying disease can get potentially life-saving treatment, while others with no signs of disease can be spared an unnecessary and expensive regimen of medications,” Guerci added.

The St. Francis Heart Study compared the prognostic accuracy of electron beam computed tomography-derived coronary calcium scoring with that of standard coronary artery disease ( CAD ) risk factors and C-reactive protein ( CRP ) in apparently healthy adults.

Between July 1996 and March 1999, 4,903 asymptomatic men and women ages 50 to 70 underwent electron beam CT scanning of the coronary arteries. At 4.3 years, follow-up was available in 4,613, or 94 percent of participants.
Of these, 119 had sustained at least one atherosclerotic cardiovascular disease event ( ASCVD ). End points included coronary death, nonfatal myocardial infarction ( MI ), surgical or percutaneous coronary revascularization procedures, non-hemorrhagic stroke and peripheral vascular surgery.

Subjects with ASCVD events had higher baseline coronary calcium scores than those without events.
The coronary calcium score predicted CAD events independently of standard risk factors and CRP ( p=0.004 ), was superior to the Framingham risk index in the prediction of events ( p=0.0006 ) and enhanced stratification of those falling into the Framingham categories of low, intermediate and high risk ( p<0.0001 ).

Subjects with coronary calcium scores above the 80th percentile for age and gender ( n=1005 ) were invited to participate in a double-blind, placebo-controlled trial of Atorvastatin ( Lipitor ) and vitamins E and C.
Study participants were randomized to atorvastatin 20 mg daily, vitamin C 1 g daily and vitamin E 1,000 U daily ( n=490 ), versus placebo ( n=515 ). All participants also received Aspirin 81 mg daily.

Treatment reduced total cholesterol by 26.5 to 30.4 percent ( p<0.0001 ), low-density lipoprotein cholesterol by 39.1 to 43.4 percent ( p<0.0001 ) and triglycerides by 11.2 to 17.0 percent ( p=0.02 ).
Treatment reduced ASCVD events by 28 to 45 percent.
A higher dose of atorvastatin would probably have produced even greater reductions in events.

The study also showed that cholesterol reduction did not retard the rate of progression of the coronary calcium score. This means that fast CT scanning of the coronary arteries is not an effective method of monitoring the response to treatment.

Source: St. Francis Hospital, The Heart Center, 2005


XagenaMedicine2005