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INR Self-Management: A promising tool to achieve low complication rates after mechanical heart valve replacement

During recent decades, heart valve replacement has become a frequent intervention in cardiovascular medicine. Mechanical heart valves account for approximately 70 % and biological heart valves for approximately 30 % of totally implanted heart valves. Because biological heart valves are durable for only 8 to 12 years in the aortic position and only 6 to 8 years in the mitral position, these implants are restricted to elderly patients.

When compared to biological valves, mechanical heart valves require continuous oral anticoagulation to prevent thromboembolism. In 1988, Butchart published a paper in which he demonstrated that patients whose INR adjustment values were monitored by doctors over a period of 88 months, in excess of 50 % of these values were outside the therapeutic range. The majority of the values were below the specified therapeutic limit.

The success rate of cardiologic diagnostics relating to heart valve diseases is remarkably good. The same holds true for cardiosurgical procedures. The perioperative mortality associated with elective heart valve replacements has dropped in the last four decades to below 4 % (in Europe). However, the period after this procedure is overshadowed by the following observations. Occurrence of major bleeding or thromboembolisms with ongoing anticoagulant regimes lies at approx. 6 % per patient year. This means that after 10 years, no less than 60 % of heart valve replacement patients following anticoagulation regimes have lived through a serious complication. This issue was taken up again and investigated as part of the ESCAT Studies. The results are very welcome indeed. The improvement in the quality of the oral anticoagulation achieved by INR self-management is impressive. Approx. 80 % of the data (patient readings) is within the therapeutic range. In addition, the variation of readings could be significantly reduced and patients could be put on a low dose regime. This resulted in a thromboembolism rate reduction of 0.2 % per patient year and reduced bleeding complications to 0.56 % per patient year. Compared to conventional therapy administered by the local GP, this means that for 100 patients per year the significant Marcumar-related complication rate could be reduced from 6 to 1. Assuming a 10 year projection, in our case 60 patients out of the 100 would have lived through a serious complication while the number of patients in case of INR self-management would only be 8. Moreover, we can currently state that approx. 90 % of the patients using INR self-management following a mechanical heart valve replacement are still alive after 10 years while enjoying a high quality of life at a mean implantation age average of 59 years.

In all, in relation to oral anticoagulation after a mechanical heart valve replacement, INR management has led to sensational improvements for patients; and this includes patients with varying levels of education.  Our future aim is to make these systems more universally available enabling every patient who had a heart valve replacement to use these systems.

PD Dr. med. Heinrich Koertke
Heart and Diabetic Centre Northrhine-Westphalia, Clinic for Thoracic and Cardiovaskular Surgery, Bad Oeynhausen (Germany)

“Living with anticoagulants” World Congress of Cardiology 2006, Barcelona,
Chairpersons: J.M. Hasenkam( Aarhus), C. Schaefer (Ratingen),
Nonprofit Organisation Symposium organized by ISMAAP (International Self-Monitoring Association for oral Anticaogulated Patients)

September 3rd, 2006