MedWire News: A substudy of the PLATO trial has shown that ticagrelor does not adversely affect pulmonary function in acute coronary syndrome (ACS) patients.
This finding comes despite the increased incidence of dyspnea observed with ticagrelor in the main study, remark Robert Storey (University of Sheffield, UK) and co-authors in the American Journal of Cardiology.
As reported previously by MedWire News, the PLATO (Platelet Inhibition and Patient Outcomes) trial randomly allocated 18,624 ACS patients to receive treatment with either ticagrelor 180 mg loading dose followed by 90 mg twice daily, or clopidogrel 300-600 mg loading dose followed by 75 mg daily thereafter, on top of aspirin therapy, for an average treatment period of 9 months.
At the 1-year follow-up, patients in the ticagrelor group had a 16% reduction in the primary endpoint of cardiovascular death, myocardial infarction, or stroke (p<0.001) compared with those who received clopidogrel.
The findings of the main study suggested an increased risk for dyspnea among ticagrelor patients, compared with those receiving clopidogrel.
To investigate further, Storey and team carried out a substudy to assess the effect of ticagrelor on pulmonary function in 199 patients from the PLATO trial who received treatment with ticagrelor 90 mg twice daily (n=101) or clopidogrel 75 mg daily (n=98). Patients with advanced lung disease or congestive heart failure, or those who underwent coronary artery bypass graft surgery after the index event were excluded from the analysis.
The researchers measured blood oxygen saturation using pulse oximetry, forced expiratory volume in 1 second (FEV1), vital capacity, and expiratory flow between 25% and 75% of forced vital capacity before and 20 minutes after inhalation of beta-2 agonist using spirometry, lung volume, and diffusion capacity 30-40 days after patients started receiving treatment. These tests were then repeated less than 10 days before and approximately 30 days after treatment discontinuation.
The findings revealed that after a mean treatment period of 31 days, there were no significant differences between the groups for any of the pulmonary function parameters.
This lack of difference between the groups persisted even after the end of the treatment period (211 days) and discontinuation of medication (32 days after last dose).
Indeed, FEV1 was similar in the ticagrelor and clopidogrel groups before and 20 minutes after beta-2 agonist inhalation, with no significant change over time and after treatment was discontinued.
"The lack of change in pulmonary function over time, including after the discontinuation of either study drug provides reassurance that there was no transient adverse effect of ticagrelor in the study population," conclude the authors.
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PLATO: Ticagrelor beats clopidogrel in ACS