New preventive cardiac disease screening guidelines SHAPE-ing up
The first SHAPE guidelines established standards for implementation of scientifically proven atherosclerosis tests to detect subclinical disease in the coronary and carotid arteries, and recommended the tests be incorporated into routine screening for all asymptomatic men aged 45 to 75 years and asymptomatic women aged 55 to 75 years, except for those defined as very low risk because of the absence of known risk factors. These guidelines became the basis for the Texas Heart Attack Prevention Bill, signed into law in Texas in August 2009.
SHAPE Task Force II will consider what has been learned through research and medical practice during the past four years. Members of the SHAPE Task Force II convened in late July and early August to discuss advances in the understanding of and technology for heart attack prevention.
"We know how to treat people after they've had a heart attack. It's well described. But we still have a problem finding people at risk of their first heart attack," said Erling Falk, MD, a professor of pathology and cardiology at Aarhus University Hospital in Denmark and chief of SHAPE guidelines editorial committee, in a video statement from the Houston-based SHAPE.
SHAPE members have focused on three biomarkers: coronary artery calcium (CAC) score via CT, carotid intima-media thickness (CIMT) and carotid plaque via ultrasound, and C-reactive protein (CRP) via a blood test. In a video statement, Sanjay Kaul, MD, a cardiologist at Cedars-Sinai Heart Institute in Los Angeles, said: "CRP has all the attributes for a good biomarker—it can be measured relatively easily and is inexpensive—but its performance is relatively rather modest. I don't think CRP is ready for routine use to identify asymptomatic patients with coronary artery disease. Coronary artery calcification performs relatively better, but is that good enough for clinical practice?"
The task force will be reviewing newer screening tools, including new biomarkers, proteomics and genomics, as well as other imaging modalities.
"We're looking for a good reliable predictor because the ones we have currently perhaps don't pass the muster," Kaul said.
Michael Davidson, MD, director of preventive cardiology at the University of Chicago Pritzker School of Medicine, proposed using results from the JUPITER study to start statin therapy on appropriate candidates, but then to further stratify intensification of therapy by using results from a CAC score or CIMT/plaque measurement.
Raimund Erbel, MD, a professor of medicine at the University of Essen in Germany, said that the Heinz Nixdorf Recall Study, the German version of the MESA study in the U.S., found that CAC scoring was superior to traditional risk factors. "The population should be anxious to get access to these new imaging modalities because they demonstrate people who are feeling good but are at risk."
For instance, the Heinz Nixdorf Recall Study found that CAC scoring beat out CRP, HDL and multiple other biomarkers for net reclassification improvement.
"The additive value of high-sensitivity CRP was significant but calcium was better," Erbel said in a video statement. "Also, CIMT significantly correlated to events and improved risk prediction beyond traditional risk factors, but not at the level of calcium scoring."
Addressing concerns about radiation exposure, Daniel S. Berman, MD, chief of cardiac imaging at Cedars-Sinai Heart Institute, said, "The methods that bring the calcium scan down to 1 mSv level are in common use at the present time. In fact, the MESA study, which was done in multiple centers, has an average of 1 mSv for their CAC scans."
He added that prospective sequential imaging for coronary CT angiography (CCTA) screening routinely delivers a radiation dose less than 3 mSv. "These are such small amounts of radiation, that in the appropriate age group, these are studies that should be done whenever they are indicated," Berman said.
Harvey S. Hecht, MD, director of cardiovascular CT at Lenox Hill Hospital in New York, said CCTA of the coronary arteries is not quite ready for screening purposes because of the radiation and the contrast. However, he made some exceptions, particularly in "younger people with a positive family history for premature coronary disease in whom you can detect noncalcified plaque which might put them at risk even though they do not yet have any calcified plaque."
The problem with Framingham risk factors is they are based on population studies and cardiologists extrapolate the data to the individual. Today, the emphasis is on individualized medicine. CAC scores and CIMT measurements are highly individualized and tell physicians exactly what is going on within each patient, Hecht said.
"The pace of advances in preventive cardiology in the years since the publication of the first SHAPE guidelines necessitates this review to ensure physicians and patients around the world benefit from scientifically valid methods of heart attack risk assessment and reduction strategies," said Prediman K. Shah, MD, chairman of the SHAPE scientific board and director of the division of cardiology at Cedars-Sinai Heart Institute and Medical Center. "This effort to refine and update the SHAPE guidelines is based on scientific proof that atherosclerosis tests can discover heart attack risk in apparently healthy patients early enough to give physicians an opportunity to persuade at-risk individuals to implement intensive therapies before it's too late."