Biomedical subjects

Gary L Grunkemeier

Publications and source records attributed to Gary L Grunkemeier.

39 records · Page 3Linked to original sources

PubMed2002

Better anticoagulation control improves survival after valve replacement.

OBJECTIVE: We sought to assess the effect of anticoagulation control on long-term survival after valve replacement with the Medtronic Hall valve (Medtronic, Inc, Minneapolis, Minn). METHODS: Prospective follow-up data, including 82,297 international normalized ratios, were collected for 1476 patients undergoing single valve replacement with the Medtronic Hall valve between 1979 and 1994, with follow-up to the end of 1998. After excluding 204 patients who either died within 30 days or had fewer than 10 international normalized ratios recorded beyond 30 days, there were 10,203 patient years of follow-up for analysis. Anticoagulation variability was measured as the percentage of international normalized ratios outside a target range of 2.0 to 4.0 for each patient. RESULTS: Linearized rates for late death rose progressively with increasing deciles of anticoagulation variability for both aortic and mitral valve replacement (2.7% and 3.3% per year, respectively, in deciles 1 and 2 up to 9.5% and 14.6% per year, respectively, in deciles 6-10; P <.001). Survival at 15 years after aortic valve replacement was 59% for low anticoagulation variability (deciles 1 and 2), 55% for intermediate anticoagulation variability (decile 3), and 28% for high anticoagulation variability (deciles 4-10); survivals at 15 years after mitral valve replacement were 56%, 42%, and 24%, respectively (P <.001 between low-intermediate anticoagulation variability and high anticoagulation variability for both aortic and mitral valve replacement). On multivariate analysis, significant predictors of reduced survival were anticoagulation variability per 20% increase (hazard ratio, 1.8), diabetes (hazard ratio, 1.6), decade of age (hazard ratio, 1.6), concomitant coronary artery bypass grafting (hazard ratio, 1.5), male sex (hazard ratio, 1.4), hypertension (hazard ratio, 1.4), New York Heart Association class III or IV (hazard ratio, 1.3), and non-sinus rhythm (hazard ratio, 1.2). Patients with low anticoagulation variability who were in sinus rhythm and did not have diabetes, coronary bypass grafting, or hypertension had survivals equal to those of the age- and sex-matched general population at 15 years. The incidence of valve-related deaths was significantly higher with high anticoagulation variability compared with the incidence with low-intermediate anticoagulation variability for both aortic (1.4% vs 0.5% per year, P <.001) and mitral valve replacement (1.5% vs 0.5% per year, P <.001). By means of univariate analysis, high anticoagulation variability was significantly associated with New York Heart Association class III or IV at 5 years postoperatively (P <.001) and with age of greater than 60 years at the time of the operation (P =.002). CONCLUSIONS: High anticoagulation variability is the most important independent predictor of reduced survival after valve replacement with a mechanical valve. Better anticoagulation control should improve survival.

Adolescent↗

PubMed2002

Using Bayes' theorem to answer a practical heart valve question.

BACKGROUND AND AIM OF THE STUDY: The risk of thromboembolism (TE) risk in a heart valve patient who has lived perhaps for 15 years since implant without TE or thrombosis is unknown. As patients are heterogeneous with regard to embolic risk, these patients must have a lower than average risk; whether this risk reduction could be quantified was the aim of the present study. METHODS: If all patients had the same risk, the TE-free curve would be exponential, with a constant hazard (equal to the 'linearized' rate). With a mixture of risks in a population, the population hazard will be a decreasing function of time. By fitting a certain parametric function to the TE-free curve, the mixing distribution can be estimated. Subsequently, given an observation for a particular patient, e.g. zero emboli in 15 years, Bayes' theorem can be used to update the mixing distribution for these patients. RESULTS: Using observed TE-free curves for Starr-Edwards valves, the mixing distribution for TE-free periods from one to 25 years was estimated. Because the risk distributions were skewed, the mean value was higher than the median. The mean (median) risk (% per year) fell from 4.5 (1.8) at implant to 1.7 (0.7) at 15 years for the aortic position, and from 7.0 (3.4) to 2.4 (1.2) for the mitral position. Thus, the average risk after 15 years was approximately 35-40% of the risk at implant for both the aortic and mitral positions, using either the mean or median risk. CONCLUSION: The mean risk for patients after 15 TE-free years is approximately one-third of the risk of all patients at implant. However, there is a wide range, with some patients still having higher risks. Bayes' theorem is useful for deriving such answers. Linearized rates have limited value for describing TE risk in a heterogeneous population.

Aortic Valve↗

PubMed2002

Clinical evaluation of the carbomedics prosthesis: experience at providence health system in Portland.

BACKGROUND AND AIMS OF THE STUDY: This study details the authors' experience with the CarboMedics bileaflet mechanical prosthesis, and assesses the valve's efficacy in terms of early mortality and long-term morbidity. METHODS: Between July 1994 and December 2000, a total of 696 CarboMedics valves was implanted in 616 patients. Aortic valve replacement (AVR) was performed in 350 (57%) patients, mitral valve replacement (MVR) in 161 (26%), double (aortic + mitral) valve replacement (DVR) in 79 (13%), and other procedures in 26 (4%). RESULTS: There were 32 operative deaths. Operative mortality was 4.3% for AVR, 6.8% for MVR, and 7.6% for DVR. Linearized rates for late death were 3.4%/patient-year (pt-yr), 5.5%/pt-yr and 7.7%/pt-yr for AVR, MVR and DVR, respectively. Survival at five years was 80.1% for AVR, 73.0% for MVR, and 64.6% for DVR (p = 0.004). Freedom from reoperation at five years was 97.6% for AVR, 98.1% for MVR, and 94.1% for DVR (p = 0.718); freedom from thromboembolism at five years was 96.3% for AVR, 98.6% for MVR, and 88.3% for DVR (p = 0.04). Linearized rates of late thromboembolism were 0.7%/pt-yr, 0.4%/pt-yr and 2.3%/pt-yr, respectively. Freedom from PVE at five years was 98.4% for AVR, 97.0% for MVR, and 89.7% for the DVR group (p = 0.172). Linearized rates of PVE were 0.5%/pt-yr, 0.9%/pt-yr and 1.8%/pt-yr, respectively. Freedom from anticoagulant-related bleeding at five years was 98.0% in the AVR group, 97.8% in the MVR group, and 88.3% in the DVR group (p <0.001); linearized rates of this event were 0.4%/pt-yr, 0.6%/pt-yr and 3.2%/pt-yr, respectively. One valve thrombosis was found after MVR, and another in the mitral position after DVR. CONCLUSION: Early and intermediate-term follow up of the CarboMedics prosthesis indicates that the clinical performance of this valve is satisfactory, and results are comparable with those obtained for other mechanical valves.

Adolescent↗