ORLANDO — Introducing his talk on guidelines for assessing acute coronary syndrome and the usefulness of biochemical markers, Elliott Antman, MD, recalled his first patient as an intern. He has kept the notes on her condition upon presenting to the physician ever since.
In addition to three hours of chest pain, the patient had diabetes, among a host of other ailments, and what Ant-man, chief of the cardiac unit at Brigham & Women's Hospital (Boston), found was that her "treatment reflected the lack of alternatives" at the time.
"Why were our therapeutic strategies so poor 31 years ago?" he asked as part of his plenary session presentation at this week's joint International Federation of Clinical Chemistry/American Association for Clinical Chemistry (AACC; Washington) annual meeting here. Emphasizing the "explosion of [biomarkers] that are now being investigated," he said that all of these now extend, currently and potentially, the therapeutic possibilities for cardiac care.
Today, said Antman in an underlining emphasis, "biochemical markers [for] myocardial necrosis are critical."
Another advancement, he said, has been the recommendations and guidelines of the American Heart As-sociation (AHA; Dallas) by "thought leaders in clinical chemistry" concerning how to use biomarker tests, noting that these tests now play across the full spectrum of cardiac care, from diagnosis and prognosis to therapeutic guidance.
The "statin decade" also has emerged to improve cardiac care. Statins, Antman said, have been "excellent," not only in preventing myocardial infarction in individuals with high risk, but also in patients with lower risk, he said.
And the role of inflammation in heart disease — and how to diagnose it — is a "hot area of investigation," he said.
"Creatinine [kinase] protein has been the most important inflammation measurement to date," Antman said, adding that it has been determined to be a predictor of high risk for a cardiac event.
In one major study, individuals with high LDL — the measurement of so-called "bad" cholesterol — were shown to have the "highest risk of a cardiac event."
The conclusion to draw is that it is better to look at both the protein and cholesterol tests than one or the other, according to Antman.
But the cardiac marker test that has truly "revolutionized" the care of heart patients is the troponin test. Troponin tests are typically used in emergency departments when patients present with chest pain, and they can tell physicians if the person is experiencing a heart attack by determining if there has been heart damage.
By being able to measure troponin, "cardiologists have learned a great deal from their clinical chemistry colleagues," he said.
Among the advantages of troponin testing he pointed to are its ability to perform risk stratification, its strong sensitivity and specificity and the ability to detect a recent myocardial infarction. But the assay comes with some downsides, such as low sensitivity after four hours of onset of chest pain and thus the need to repeat it after about eight hours.
Antman noted that the American College of Cardiology (ACC; Bethesda, Maryland) and AHA guidelines concerning unstable angina suggest that physicians should not totally rely on troponin tests alone for evaluating patients.
In a Q&A session following his talk, he was careful to say that "these biomarkers should not be evaluated in isolation" and that, for example, there could be results of elevated troponin in "cases other than ischemia."
In one more example, Antman said that peak elevation in both CK-MB (creatinine kinase-myoglobin) and troponin tests is "much higher in both tests in reperfused patients."
Still another use of diagnostic biomarkers is in the determination of re-infarction; however, Antman said it has been suggested that re-evaluation of biomarker changes should be accompanied by at least one recurrent symptom, such as chest pain.
Another key biomarker for cardiac care is B-type natriuretic peptide (BNP), which Antman said is "useful for diagnosing heart failure in patients with shortness of breath."
Antman made reference to the NACB statement from its Laboratory Medicine Practice Guideline.
"It alludes to combining biomarkers useful in assessing risk of 30-day myocardial infarction," he said, adding that the statement offers "sound logical rationale for early use of these markers."
Describing the characteristics of an "ideal" cardiac marker, Antman said these should include easy and reliable measurement, incremental prognostic value, good guidance to clinical decision-making and cost-effectiveness; the latter, for example, offered by a 12-lead EKG.
Going forward, he recommended that cardiologists and clinical chemistry colleagues work "collectively" on making the maximum use of information and look to expand multi-markers. He said there should also be refinement of therapeutic strategies and response to biomarker measurements.
"I believe there is value in serial evaluation with biomarkers," Antman said
And looking to the future, he predicted that he and his colleagues will be discussing "at gatherings like this" pharmacogenomics and proteomics.