Article

Late incidence and determinants of stroke after aortic and mitral valve replacement

Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Ontario, Canada.
The Annals of thoracic surgery (Impact Factor: 3.65). 08/2004; 78(1):77-83; discussion 83-4. DOI: 10.1016/j.athoracsur.2003.12.058
Source: PubMed

ABSTRACT Stroke is a devastating complication in patients with prosthetic valves, but characterization of its late occurrence from a large cohort is lacking.
Three thousand one hundred eighty-nine adult patients who underwent a total of 3,576 operations for left-heart valve replacement were managed with contemporary anticoagulation guidelines and prospectively followed in a dedicated clinic. Total follow-up was 20,096 patient years. Bootstrapped survival analysis was used to determine the impact of patient and valve related factors on the incidence of stroke.
Most strokes were embolic. Linearized embolic stroke rates were 1.3% +/- 0.2% per year for aortic bioprostheses, 1.4% +/- 0.2% per year for aortic mechanical valves, 1.3% +/- 0.3% per year for mitral bioprostheses, and 2.3% +/- 0.4% per year for mitral mechanical valves (p = 0.002, vs other implant types). Age more than 75 years, female gender, and smoking were independent risk factors after aortic and mitral valve replacement. Atrial fibrillation, coronary disease, and tilting-disc mechanical prostheses were independent predictors of embolic stroke after aortic valve replacement. Preoperative left ventricular (LV) dysfunction was an independent risk factor in patients with mitral prostheses. Primary operative indication, diabetes, redo status, or the presence of two prosthetic valves were not associated with an increased hazard. The addition of acetyl salicylic or dipyridamole to warfarin anticoagulation did not significantly lower embolic stroke risk in patients with mechanical prostheses.
Approximately 20% of patients with valve prostheses have an embolic stroke by 15 years after valve replacement. Some risk factors such as the avoidance of smoking, mitral mechanical prostheses, aortic tilting-disc valves, and proceeding to mitral surgery before LV dysfunction occurs are potentially modifiable.

Full-text

Available from: Pierre Bedard, Mar 12, 2014
0 Followers
 · 
89 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVES: The study aimed to determine if mitral valve repair (MVRR) or bioprosthetic mitral valve replacement (BMVR) without postoperative anticoagulation is associated with a similar risk of thromboembolism and death as anticoagulation. METHODS: We retrospectively reviewed our 2004-09 experience in 249 MVRR and bioprosthetic replacement patients (53% female; 63 year mean age). Concurrent procedures principally included antiarrhythmic surgery, aortic valve replacement, tricuspid valve repair and coronary bypass grafting. Warfarin therapy was instituted at the discretion of the surgeon. Thirty-day, a period known to have the highest risk of valve-related thromboembolism, outcomes were compared relying on the incidence of stroke and death as surrogates of thromboembolic complications. Intermediate-term survival was compared between the groups using Cox proportional hazard models. The mean follow-up was 2.9 years. Given the non-randomized warfarin use, a propensity score using patient comorbidities and concurrent procedures was created and added to the Cox models. RESULTS: One hundred and ninety-two (77%) patients were discharged on warfarin and 57 (23%) were discharged without warfarin. Thirty-day mortality in patients discharged from the index hospitalization was 1.2% and was similar for the two groups (P = 0.99). Four ischaemic perioperative strokes were detected; 3 in the warfarin group and 1 in the no warfarin group (P = 0.99). Overall survival was 84%, with 84% survival in the warfarin group and 86% in the no warfarin group (P = 0.79). Bleeding complications were comparable between the two groups (P = 0.72). In a multivariate analysis, warfarin was not related to mortality. CONCLUSIONS: Despite current guidelines recommending postoperative anticoagulation following MVRR or bioprosthetic replacement, the avoidance of warfarin does not increase perioperative complications and has no impact on intermediate survival. Accordingly, a prospective randomized study to adjudicate the role of extended warfarin thromboprophylaxis in mitral valve surgery is warranted.
    European journal of cardio-thoracic surgery: official journal of the European Association for Cardio-thoracic Surgery 01/2013; 44(1). DOI:10.1093/ejcts/ezs626 · 2.81 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The rationale for the Ross procedure and for valve-sparing aortic root procedures is predicated on the presumption that traditional composite graft replacement of the aorta and aortic valve will be complicated by late thromboembolism and by warfarin-related bleeding. We evaluated this presumption by determining late followup after composite graft replacement of the ascending aorta and aortic valve. One hundred six consecutive patients (21 female, 85 male) underwent composite graft replacement between January 1995 and November 2004. Mean age was 54.5 years. Indication for surgery was chronic aneurysm in 93 patients and acute type A dissection in 13. St. Jude mechanical valve conduit was used in 95 (89.6%) patients (mean size=23 mm, range-19–31 mm), whereas 11 patients (10.4%) received a biological conduit (mean size-23 mm, range-19–27 mm). Warfarin goal for the St. Jude group was INR 1.8–2.2. Hospital mortality was 5.6% (6/106), including stroke 2.8% (3/106) and bleeding 1.8% (2/106). In-hospital morbidity was 12.2% (13/106). With a postoperative followup ranging from 1 to 114 months (mean-44.4), late causes of death were stroke in two patients (2%). Kaplan–Meier curves show five-year postdischarge survival at 97.3% and eight-year survival at 91.2%. Event-free survival was 89.3% at five years followup and 76.2 at eight years. Thromboembolism and bleeding complications were minimal in midterm followup after composite graft replacement. This information renders composite graft replacement relatively more attractive versus the surgical alternatives than previously appreciated.
    International Journal of Angiology 07/2005; 14(3):118-122. DOI:10.1007/s00547-005-2050-x
  • [Show abstract] [Hide abstract]
    ABSTRACT: Parallel processing methods with constrained nonlinear optimization were developed to show the potential to efficiently perform chemical process design calculations. A sequential optimization subroutine was developed that used a SQP algorithm and the BFGS inverse Hessian update. This subroutine had parallelism introduced at various points. Most of these methods examined ways to perform and use the parallel simultaneous function and gradient evaluations. Function evaluations are generally expensive calculations in chemical process optimization. Algorithms using a parallel finite difference Hessian (PH), Stracter's parallel variable metric (PVM) update, and Freeman's projected parallel variable metric (PPVM) update were investigated. Other algorithms investigated included Schnabel's parallel partial speculative gradient evaluation and parallel line searching. The success of a global optimization algorithm using simultaneous minimization shows potential for robust and reliable global minimization of complex multiextremal problems. The results of this work show the potential of decreasing large scale problem optimization time with parallel processing.
    Computers & Chemical Engineering 06/1995; 19(6):807-825. DOI:10.1016/0098-1354(94)00082-4 · 2.45 Impact Factor