Reports

This report is based on medical evidence presented at sanctioned medical congress, from peer reviewed literature or opinion provided by a qualified healthcare practitioner. The consumption of the information contained within this report is intended for qualified Canadian healthcare practitioners only.

PRIORITY PRESS - Canadian Cardiovascular Congress 2009

Edmonton, Alberta / October 24-28, 2009

Dr. Michael Chan, Associate Professor of Medicine, University of Alberta, Edmonton, and his colleague at the Royal Alexandra Hospital’s C.K. Hui Heart Centre, Dr. Po Kee Cheung, chaired Tuesday’s symposium on global treatment strategies of cardiovascular disease (CVD).

As discussed during this session by Dr. Matthew Budoff, Los Angeles Biomedical Research Institute at Harbor-UCLA, Torrance, California, cardiac computed tomography (CT) is a rapidly evolving imaging modality that could transform certain aspects of cardiology in the near future. As he wrote in the Texas Heart Institute Journal (2006;33:197-200), cardiac CT offers unique applications distinct from other imaging modalities in broad use today. “The first is in the measurement of calcium scores for screening patients with an intermediate Framingham risk.”

Current guidelines cite six different target levels for LDL-C depending on the patient’s level of CV risk. Cardiac CT can more precisely risk-stratify patients in the intermediate risk range, as Dr. Budoff indicated. For example, a score of 0 indicates no detectable coronary calcium, and reassures patients who do not have advanced plaque that they are at very low risk of CV events. However, as the calcium score rises to over 100, “we start to move into what is considered a National Cholesterol Education Program high risk of 2% per year or a 20%, 10-year-risk,” Dr. Budoff stated. A recent study indicated that patients were 10 times more likely to have a myocardial infarction (MI) if they had a calcium score of over 100, suggesting that the calcium score significantly adds to the predictability of patients having a future MI.

Cardiac CT can also help identify patients who may not require further diagnostic evaluation after an equivocal test result, such as might be obtained on treadmill testing. Because the negative predictive value of the calcium score is high, it is unlikely a patient has obstructive coronary artery disease (CAD) if the score is negative. “Another potential application for CT is monitoring the progression of disease over time,” Dr. Budoff observed. More studies indicate that patients whose calcium scores did not increase over time had no cardiac events, whereas among those whose scores continued to rise, CV event rates were very high.

Most encouraging of all, the use of cardiac CT for non-invasive angiography may eventually replace invasive angiography under certain circumstances. “Non-invasive angiography is quite straightforward and it allows visualization of both the stenoses of the arteries as well as arterial plaque, so we can better identify those patients who may need either invasive procedures or aggressive medical therapy,” Dr. Budoff remarked. “I think there is a lot of interest among cardiologists and radiologists in this modality and that it will catch on quite rapidly when physicians are familiar with it.”

Reducing CVD Disability, Death

Dr. Robert Califf, Vice Chancellor for Clinical Research, Duke University, Durham, North Carolina, applied his considerable academic knowledge to discussing health systems that could lower death and disability from CV disease. Historically, systems designed to track how well physicians were dispensing evidence-based care have been based on clinical trials, after which guidelines are usually created and their implementation tracked. “The higher the implementation rate, the lower the rate of CV death and disability,” stated Dr. Califf. However, the best evidence supporting whether this particular model works comes from “provider-driven medical care systems”—in other words, physician-based—and not from models based on the neighbourhood, the community, the workplace or schools where patients at risk for CVD really function. For example, a school may keep a record of a child’s health status but physicians are not usually privy to school information and may impose a regimen that is at variance with how the school is caring for the child.

Similarly, it is not unusual for an elderly patient to be seeing four or five different physicians, all of whom may be prescribing different or the same medications without knowingly overlapping others’ efforts. With the development of electronic health records, however, the whole picture could shift, as Dr. Califf predicted, because that record could then belong to the family and the family would be responsible for sharing it with all providers, enabling everyone to be on the same “page,” so to speak. From there, it would be easier to organize support at a local level and encourage patients to follow a prescribed regimen, improve adherence and optimize their care rather than leaving patients to their own devices once they leave the caregiver’s office. “We will add 500 million life-years between now and 2015 if we reduce mortality from chronic disease in the global population by just 2%,” Dr. Califf wrote in The Texas Heart Institute Journal (2006;33:192-6). “But this will require a different way of doing business than our current fractured, somewhat dysfunctional system and it will be up to us to figure out how to do it.”

Expanding Biomarker Capabilities

As discussed by Dr. Bruce McManus, Director, Providence Heart & Lung Institute, and Professor of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, the search is on to develop more accurate, precise, sensitive and specific biomarkers that will better discriminate between the presence or absence of different heart and blood vessel disease as well as more accurately predict individual risk of disease, its progression and response to different treatment modalities.

Some cardiac biomarkers have already proven useful—C-reactive protein, for example, in the setting of atherosclerosis, cardiac troponins in the setting of acute MI and brain natriuretic peptide in the setting of heart failure. Yet over the past number of decades, “the process for identifying useful clinical biomarkers has been very slow and unpredictable,” Dr. McManus remarked in an interview during the scientific sessions. That process, however, has recently been fast-forwarded, thanks to the explosion of high-performance “-omic” technologies including genomics, proteomics and metabolomics.

The notion of being able to track patients anywhere along the “life cycle” of their illness using reliable, easily retrievable biomarkers is inherently revolutionary, as Dr. McManus suggested, because they could dramatically alter how physicians advise and treat a patient. “Much of current biomarker development efforts are... aimed at identifying non-invasive ways of monitoring progression and diagnosing clinical events in relation to current or new therapeutic agents,” Dr. McManus reported in The Canadian Journal of Cardiology (2009;25(Suppl A):9A-14A). But “upstream” biomarkers of early disease and even risk of disease could prove much more beneficial for patients—and most cost-effective—if physicians could anticipate disease risk and modify that risk before disease onset.

Dr. McManus also predicted the same “-omic” technologies would give a much-needed boost to pharmaceutical development, where effective surrogate biomarkers would allow for shorter clinical trials, more cost-effective drug discovery and more rapid implementation of beneficial therapies.

“The promise of improvements in clinical care and accelerated drug development offered by successful biomarkers, juxtaposed with the catastrophic consequences of their failures, brings into clear focus the need for well-designed and rigorously executed assessment for biomarker identification, validation, qualification and implementation,” concluded Dr. McManus in his article.