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A study led by McMaster University researchers found high doses of Clopidogrel ( Plavix ) significantly reduce complications in heart patients undergoing angioplasty to clear blocked arteries.

Angioplasty, also known as percutaneous coronary intervention ( PCI ), carries with it the risk of a myocardial infarction and stent thrombosis, the formation of life-threatening blood clots inside stents that prop open narrowed arteries.

An international group of researchers from 39 countries found patients undergoing angioplasty benefited from a more aggressive antiplatelet regimen in which they were given double the standard dose for about a week.

The investigators simultaneously evaluated the optimal dose of Acetylsalicylic Acid ( Aspirin ) and found that 300 mg of Acetylsalicylic Acid resulted in similar outcomes to 100 mg of Acetylsalicylic Acid and was not associated with higher rates of bleeding. There was also no benefit of the higher dose of Clopidogrel in the 7,000 individuals not undergoing PCI.

CURRENT-OASIS 7 ( Clopidogrel Optimal Loading Dose Usage to Reduce Recurrent EveNTs/Optimal Antiplatelet Strategy for InterventionS ) is a Phase III, multicentre, multinational, randomized, parallel-group trial which enrolled 25,087 patients scheduled to undergo angiography within 72 hours of arriving in a hospital emergency department or coronary care unit with unstable angina or a myocardial infarction. Of these, about 17,000 were suitable for angioplasty and underwent the procedure.

As soon as possible after their arrival, patients were randomly assigned to the high dose or standard dose of Clopidogrel for a month. High-dose patients received 600 mg of Clopidogrel on the first day – as early as possible before angioplasty – then 150 mg once a day for seven days, followed 75 mg daily for the remainder of the month. Those patients on the standard regimen received 300 mg on day one, followed by 75 mg once a day until day 30. Patients in both groups were randomly assigned to Acetylsalicylic Acid, either high-dose ( 300-325 mg once daily ) or low-dose regimen ( 75-100 mg once daily ).

The more intensive high-dose 600 mg Clopidogrel regimen reduced the risk of stent thrombosis by an incremental 30 per cent and the risk of myocardial infarction by a further 22 per cent over and above the standard regimen in 68 per cent of patients ( 17,232 out of 25,087 ) undergoing angioplasty. There was an increase in major bleeding, but no increase in bleeds into the brain or those that were fatal.

According to Salim Yusuf, chair of the CURRENT-OASIS 7 Steering Committee, the combination of high-dose Clopidogrel combined with usual doses of Acetylsalicylic Acid may be the optimal treatment strategy in PCI patients.

Source: European Society of Cardiology, 2009

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