Is heparin reversal with protamine after carotid endarterectomy dangerous?

OBJECTIVE Although systemic heparinisation is routine during CEA, reversal with protamine is controversial with 3 studies suggesting increased peri-operative stroke rates and 3 no effect. None included independent peer-review. DESIGN Non-randomised observational study of data derived from a randomised controlled study of anaesthetic technique for CEA. METHODS Data on heparin and protamine use and risk factors potentially influencing CEA outcome were collected prospectively. Stroke, death, MI, wound haematoma and re-operation rates were recorded following independent peer-review. RESULTS 1513/2107 patients received heparin alone (H) and 594/2107 had heparin reversed with protamine (H+P). Risk factors for outcome were similar in both groups. The frequency of outcome events (H v H+P) were: stroke: 67/1513 (4.4%) v 17/594 (2.9%), p=0.098; non stroke or MI death: 10/1513 (0.7%) v 5/594 (0.8%), p=0.657; MI: 6/1513 (0.4%) v 3/594 (0.5%), p=0.718; haematoma: 157/1513 (10.4%) v 44/594 (7.4%), p=0.037; re-operation: 51/1380 (3.7%) v 18/565 (3.2%), p=0.581. CONCLUSIONS These results show a non-significant increase in stroke rate in patients receiving heparin alone refuting suggestions that protamine is harmful. Conversely post-operative haematoma was more frequent when protamine was withheld but re-operation rates were no different. Thus protamine use appears safe and should remain a matter for individual surgeon preference.