NEW YORK (Reuters Health) – The dyspnea related to use of ticagrelor rather than clopidogrel in patients with acute coronary syndromes (ACS) is not associated with pulmonary function, researchers report in a September 3rd on-line paper in the American Journal of Cardiology.

“This substudy,” Dr. Robert F. Storey told Reuters Health by email, “provides more reassurance about ticagrelor-related dyspnea, reinforcing other evidence which suggests this is a benign phenomenon.”

Dr. Storey of the University of Sheffield, UK and colleagues note that the Platelet Inhibition and Patient Outcomes (PLATO) trial showed that compared to clopidogrel, ticagrelor reduced the risk for cardiovascular events in ACS patients, but was associated with an increased incidence of dyspnea.

To investigate, the team conducted a substudy in 101 patients who were receiving ticagrelor 90 mg twice daily and 98 receiving clopidogrel 75 mg per day. A variety of pulmonary function and other tests were performed at 30 to 40 days after patients started receiving the study medication. They were then repeated less than 10 days before medication was discontinued and performed again about 30 days after treatment ended.

After a mean treatment duration of 31 days, there were no differences between the groups for any of the pulmonary function parameters. At the end of treatment (after a mean of about 7 months) and after a mean of about a month after treatment ended there were also no differences between groups.

For example, at the first visit, FEV1 before beta2 agonist inhalation was 2.81 L in the ticagrelor group. This did not change significantly at subsequent visits. The corresponding value in the clopidogrel group was 2.70, again with no subsequent changes.

The team notes that the findings of no impact on pulmonary function “complement the results of a prospective study in patients with stable coronary artery disease that also showed no evidence of any adverse effect of ticagrelor on pulmonary function despite clear evidence of ticagrelor-related dyspnea occurring early in the course of treatment.”

The researchers hypothesize that “ticagrelor-related dyspnea may be due to increased levels of extracellular adenosine…. but further work is required to explore other potential mechanisms for this dyspnea.”

Reference:
Pulmonary Function in Patients With Acute Coronary Syndrome Treated With Ticagrelor or Clopidogrel (from the Platelet Inhibition and Patient Outcomes [PLATO] Pulmonary Function Substudy)
Am J Cardiol 2011.