Postgraduate medical journal
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Randomized Controlled Trial Clinical Trial
The effect of different nitrate preparations on plasma heparin concentrations and the activated partial thromboplastin time.
There is evidence that intravenous nitrates which are frequently used in acute coronary syndromes may interfere with the anticoagulant effect of heparin. We compared the effect of two different nitrate preparations on the activated partial thromboplastin time (APTT), anti-thrombin III activity (AT III) and plasma heparin levels in patients (n = 50) undergoing routine percutaneous transluminal coronary angioplasty (PTCA) for stable angina. Patients were randomized to either: (1) intravenous heparin and nitroglycerin (GTN); or (2) intravenous heparin and isosorbide dinitrate. ⋯ Within-group analysis showed significantly lower APTT ratio and heparin concentrations at 4 hours compared with the respective 2 hour values. These results would suggest that there is a potential impairment of anticoagulation with low-dose intravenous nitroglycerin and to a lesser extent with low-dose isosorbide dinitrate. Early and frequent monitoring may therefore be appropriate when intravenous nitrates and heparin are used in combination.