CARDIOVASCULAR BIOMARKERS - EPCCS 09

DVT D-dimer testing might be useful in primary care to help with diagnosis of deep vein thrombosis (DVT), said Professor David Fitzmaurice (Birmingham, UK).

D-dimer is a fibrin degradation product. Its presence in plasma reflects turnover of clot in the body and levels are raised in DVT. However, they are also raised in other conditions, and in old age. The test is therefore sensitive but not specific for DVT.

The test has a high negative predictive value, with a normal result virtually excluding DVT diagnosis. Potentially, therefore, point-of-care testing could be used in primary care, in combination with clinical assessment, as a rule-out test for DVT. This could reduce the need for expensive ultrasound imaging — the main diagnostic tool — while also improving speed of diagnosis.

‘We can use it as a screening test in our offices to help decide whether we should be referring the patient for further investigation, ” he said. However, the test is of little value in patients with high probability of DVT as they will need imaging regardless of the D-dimer result. Professor Fitzmaurice cautioned that performance of current tests is highly variable.

CV RISK New biomarkers might add to classical risk scores for determining cardiovascular risk, said Dr Rao Kondapally (Cambridge,UK). However more robust data, including cost-benefit evaluation, are needed before these biomarkers find routine application.

Biomarkers might be useful in guiding therapeutic decisions. They might help to predict treatment response and/or tailor therapy.

In the CAPTURE and PRISM acute coronary syndrome trials, patients who derived maximum benefit from use of combination of GPIIb/IIIa inhibitors and heparin were those with higher troponin levels. In PROVE-IT, patients with the highest quartile of the novel inflammatory biomarker neopterin had greatest risk of cardiovascular disease. Also, greatest benefit of intensive statin treatment was seen in this group “giving us a clue that this is the group that we should focus on in intensive treatment regimens.” PROVE-IT also suggested that measuring C-reactive protein levels might pick-up patients who could benefit from more aggressive treatment.

Acute chest pain Point of care tests with new biomarkers may help general practitioners to make a diagnosis of myocardial infarction.

Professor Arno Hoes (Utrecht, The Netherlands) said that diagnosis of suspected MI remains tricky, even for experienced GPs. It is impossible to refer all patients who have MI in the differential diagnosis. Biomarker tests could well have a place, on top of signs and symptoms and ECG, particularly in patients with atypical symptoms.

Troponin, an important marker in MI, is of little use to GPs because levels do not rise quickly enough. Around 60% of patients are seen by GPs within 1-6 hours after the onset of pain. “That is exactly the time frame where standard troponin tests are not very good.”

Biomarkers potentially useful for primary care include high-sensitive troponin and heart-type fatty acid binding protein (h-FABP). Recent studies showed that high-sensitive troponin is better than standard troponin, particularly for patients presenting within three hours.

H-FABP is released into the circulation in response to ischaemia, and is seen early after MI. “So in theory, this could be useful in primary care,” Professor Hoes said. He is just completing a primary care study to assess its value.

Asked if there was a danger that GPs could come to rely too much on these tests, he emphasised that they are only tools, to be combined with clinical expertise.