Etiology of stroke after mechanical heart valve replacement--results from a ten-year prospective study

In patients carrying mechanical valve prostheses it is assumed that cardioembolic strokes account for 70 - 90 % of clinically diagnosed thromboembolic complications. The etiology of stroke especially in older patients with mechanical heart valves may thus be multiple and not prosthetic valve-related in a substantial percentage. It was the aim of this prospective study to analyze the etiology of stroke in consecutive patients, who had mechanical heart valve replacement before.

During a 10-year period, 89 consecutive patients were hospitalized at the authors' institution late (> 90 days) after mechanical valve replacement with definite stroke according to the WHO Monica criteria for stroke registers.

CCT or MRI revealed cerebral bleedings in 69 (77.5 %) patients, which were small in 42 (60.9 %), intermediate in 24 (34.8 %), and massive in three (4.3 %). Non-embolic, lacunary infarctions were documented in seven (8 %) and embolic strokes in 13 (17%) patients. According to the findings by CCT/ MRI and duplex sonography of the carotid arteries, stroke was considered atherothrombotic in seven of these 13 patients with embolic strokes (53.8 %). Six of these seven patients (86 %) had recurrent neurologic symptoms. In the other four, prosthesis-related stroke was most likely due to a yet undiagnosed active prosthetic valve endocarditis. In only two (2.3%) of the 89 stroke patients, was etiology probably prosthesis-related. Patients with an INR > 5.0 had ischemic stroke in three, and bleedings in four, patients with an INR < 1.8 ischemic strokes in one, and bleedings in three cases.

In conclusion, the vast majority of strokes after mechanical valve implantation in our cohort study were hemorrhagic rather than ischemic in origin, irrespective of the intensity of the oral anticoagulation. For proper treatment decisions, it is therefore essential to discriminate the underlying etiology of stroke.