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) (September 3rd, 2006)
"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)
The Early Self-Controlled Anticoagulation Trial has demonstrated that in patients with mechanical heart valve replacement self-management of oral anticoagulation results in less major thrombo-embolic events than conventional measurement by the general practitioner. However, the effects of self-management on long-term survival are currently not known.
Nine hundred thirty patients participated in a follow-up study of the aforementioned trial (488 from the self-management group and 442 from the conventional group). Long-term survival was assessed 12 years after the study began using the intent-to treat analysis as well as the per protocol analysis. Univariate and multivariate analyses were performed in order to assess independent predictors of survival.
In total, the 930 patients accrued 8,315 patient-years of observation. During follow-up, 236 patients died. According to the intent-to treat analysis, 10-year survival was 76.1% in the conventional group and 84.5% in the self-management group. The corresponding values for the per protocol analysis were 67.7% and 80.6%, respectively. Age, kind of valve surgery, and study group were independent predictors of survival. Self-management of oral anticoagulation increased long-term survival by 23% (intent-to-treat analysis) and 33% (per protocol analysis), respectively, compared with conventional measurement by the general practitioner. Possible reasons for these advantageous results in the self-management group are fewer thrombo-embolic events due to a higher percentage of international normalized ratio values lying in the target range compared with the conventional group.
Data indicate that self-management of oral anticoagulation is a promising strategy in order to increase long-term survival in patients with mechanical prosthetic valves.
PD Dr.med. Heinrich Koertke et al. Department of Cardiothoracic Surgery, Heart Center North-Rhine-Westphalia Bad Oeynhausen, Clinic of the Ruhr University Bochum, Germany
Address correspondence to Dr Koertke, Herz- und Diabeteszentrum NRW, Georgstr.11, 32545 Bad Oeynhausen, Germany
Ann Thorac Surg 2007; 83:24-9
Rationale, design, baselines and oral anticoagulation control after one year of follow-up
Self-management is safe and reliable in patients with long-term oral anticoagulation (OAC). However, no study has yet assessed the safety and efficacy of OAC self-management in elderly patients with major thromboembolic and haemorrhagic complications as primary outcomes. In this multi-centre, open, randomised controlled trial, patients aged 60 years or more were randomised controlled trial, patients aged 60 years or more were randomised into the self-management groups (SMG) (N=99) or routine care group (RCG) (N=96). We describe the rationale, design, baseline characteristics and interim analyses of oral anticoagulation control quality within the first year of follow-up. The medians of the squared international normalised ration (INR) value deviations after six and 12 months were significantly lower in the SMG with medians of 0.16 and 0.16 compared to the RCG with medians of 0.25 and 0.25. The percentage of time within target range and the percentage of INR measurements within target range were significantly higher in the SMG versus the RCG with the first six months (medians 71% vs. 58% and 69% vs. 57%), and during the second six months of the study (7% vs. 67% and 72% vs. 57%). The numbers of all thromboemblic events requiring hospitalisation, major bleeding events, and deaths were similar in both groups. These preliminary results suggest that self-management of oral anticoagulation i9s safe and feasible for elderly patients willing to participate in a structured training programme.
Andrea Siebenhofer et al. (Department of Internal Medicine, medical University of Graz, Austria); Thromb Haemost 2007; 97:408-416
Trials including older patients on anticoagulation therapy are not that common. “Studies have the tendency to exclude older patients”, commented Scott S. Kaatz, DO, MSc, FACP, Clinical Associate Professor of Medicine, Director Anticoagulation Clinics, Henry Ford Hospital, Detroit, in his talk entitled “INR self-management in the elderly”. He knows of only one trial which specifically enrolled elderly patients managing their own INR, and there are no trials on this subject comparing groups of older patients to younger ones.Kaatz also poses a fundamental question: “Who should be regarded as elderly? Does it start with 65? Or 75? We must also take into account that our life expectancy will rise during the next decades.”
Report by Thomas Klein, MD, MSc (Nov. 2009)
In mechanical heart valve recipients, low-dose international normalized ratio (INR) self-management of oral anticoagulants can reduce the risk of developing thrombo-embolic events and improve long-term survival compared with INR control by a general practitioner. Here, we present data on the safety of low-dose INR self-management.
Methods and results:
In a prospective, randomized multi-centre trial, 1346 patients with a target INR range of 2.5–4.5 and 1327 patients with a target INR range of 1.8–2.8 for aortic valve recipients and an INR range of 2.5–3.5 for mitral or double valve recipients were followed up for 24 months. The incidence of thrombo-embolic events that required hospital admission was 0.37 and 0.19% per patient year in the conventional and low-dose groups, respectively (P = 0.79). No thrombo-embolic events occurred in the subgroups of patients with mitral or double valve replacement. The incidence of bleeding events that required hospital admission was 1.52 and 1.42%, respectively (P = 0.69). In the majority of patients with bleeding events, INR values were < 3.0. Mortality rate did not differ between the study groups.
Data demonstrate that low-dose INR self-management does not increase the risk of thrombo-embolic events compared with conventional dose INR self-management. Even in patients with low INR target range, the risk of bleeding events is still higher than the risk of thrombo-embolism.
Heinrich Körtke, MD, et al. (Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center North Rhine-Westphalia Bad Oeynhausen, Germany); Eur Heart J. 2007; 28:2479.2484
Chris Gardiner, PhD, Department of Haematology, University College London Hospitals, London, United Kingdom, described the design and the results of the study "Self monitoring of oral anticoagulation: Does it work outside trial conditions?" (Journal of Clinical Pathology, February 2008, Volume: 62 (2): 168-71. Less than 1% of the estimated one million patients receiving oral anticoagulation therapy (OAT) in the UK monitor their own PT/INR. Patient self-monitoring (PSM) of OAT is known to improve anticoagulant control, but poor uptake and high dropout rates in UK studies have prompted suggestions that PSM is suitable for only a minority of patients. In this study 318 consecutive patients referred, for the first time, to an anticoagulation clinic were assessed for eligibility using established criteria. Patients electing for PSM attended training and, following successful assessment, performed a capillary blood INR every two weeks or more frequently if directed to do so by the anticoagulation clinic. The aim was to determine whether PSM is a viable alternative to regular hospital anticoagulant clinic attendance, if offered to the patient from the start of treatment. "23% of all patients receiving oral anticoagulation were suitable, willing and able to self-test," Gardiner said, summarizing the results. "The uptake is improved if offered at the start of treatment, particularly among younger patients." Two more findings: Most patients were happy to remain on self-testing rather than proceeding to self-management, and the quality of anticoagulant control achieved through PST may be superior to that of the routine specialist anticoagulant clinic. "The situation in the UK is like this: Test strips are available on prescription from the National Health Service, but some general practitioners and primary care trusts are reluctant to prescribe strips, because they are still sceptical about self-monitoring," said Gardiner. "They think that self-monitoring is suitable for only a minority of patients. But hospitals cannot cope with the increasing numbers of patients requiringanticoagulation."
Report by Thomas Klein, MD, MSc (Nov. 2009)
Treatment with vitamin K antagonists (warfarin or coumadin derivatives) requires repeated monitoring of the intensity of anticoagulation and regular dose-adjustment. Nevertheless, many patients are not in the therapeutic target range for a considerable proportion (30-50%) of the time. In addition, the repeated laboratory checks and visits to the (anticoagulation) clinic or office are time consuming and may have a negative impact on patient satisfaction. Recently, reliable portable coagulometers have become available and these devices allow the measurement of the International Normalized Ratio (INR) from a small drop of capillary blood, thereby enabling patients to self-manage their anticoagulation. Clinical studies show that self-testing of the INR and self-adjusting of the warfarin dose results in a better control of anticoagulation in comparison with regular care by general practitioners or specialists and is at least as good as management by a specialized anticoagulation clinic. Moreover, treatment-related patient satisfaction and quality of life improves in patients performing self-management of anticoagulation.
Marcel Levi, MD PhD, Chairman, Dept. of Medicine, Academic Medical Center, University of Amsterdam, The Netherlands (July, 2008)