Inpatient cardiac rehabilitation following cardiac surgery: a setting for the tailored management of antithrombotic therapy

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Cardiac rehabilitation demonstrably decreases mortality and improves quality of life in patients managed surgically for coronary artery disease and heart failure.1 In patients with heart valve disease, the evidence for its benefit is weaker in terms of re-hospitalization and death, although exercise tolerance and return to work are positively affected.2 Rehabilitation’s traditional goal is to optimize functioning in disabling health conditions.3 This definition does not cover the core of ‘heart dysfunction’ and prevention; however, cardiac rehabilitation may be a useful setting in which to tailor antithrombotic regimens following cardiac surgery. The post-surgical setting implies a pro-inflammatory milieu.4 Thrombus formation occurs in the hinge points and on the sewing rings of heart implants. The location and type valve, rhythm, time elapsed from valve implantation, and risk factors for arterial and venous thrombosis such as age, hyperlipidaemia, diabetes and metabolic syndrome, hypertension, and, specifically, hyperhomocysteinemia and antiphospholipid syndrome concur to an increased risk.5 Vitamin K antagonists (VKA) have changed the outcomes of patients with prosthesis implantation; however, their use is hampered by multiple drug and food interactions and an overall low therapeutic index, requiring routine coagulation monitoring and frequent dose adjustments. Direct oral anticoagulants (DOACs) have become available for long-term use in atrial fibrillation (AF) and venous thromboembolism (VTE). Their use has also been suggested in the post-surgical setting, although concerns about thromboembolism hinder their widespread adoption.5 The use of DOAC in patients with aortic bioprosthesis implanted by percutaneous approach with an indication for DOAC for concomitant AF has been demonstrated to be as safe and feasible as VKA, with an increased risk of gastrointestinal bleeding related to the use of edoxaban only.6 In patients without DOAC indications, single-antiplatelet therapy (SAPT) is safer and equally as effective as dual-antiplatelet therapy (DAPT) or SAPT plus a DOAC.7 In patients with mitral repair, aspirin has been documented as advantageous over VKA, as documented by retrospective, although inadequately powered, multicentre analyses.8 For patients with surgically implanted bioprosthetics who have AF, the use of DOACs has been associated with improved clinical benefit, with significant relative reduction of overall mortality in the most recent meta-analysis.9 In patients with mitral and aortic bioprosthetics without AF, a different approach is advised. Indeed, thromboembolic risk after tissue valve implantation in patients in sinus rhythm (SR) is 0.7% per year. However, it is highest for 90 days after operation and in the mitral position.5 In patients with surgically implanted bioprosthetic aortic valve replacement (BAVR), retrospective studies and a single randomized trial did not demonstrate superiority of warfarin over aspirin in preventing thromboembolic complications with or without concomitant coronary artery bypass.10 Moreover, in low-risk patients with single mechanical aortic valve replacement, a low anticoagulation intensity with an international normalized ratio (INR) of 1.5–2.5 is safe and feasible and could be considered, mostly after 3 months, further suggesting that in high-flow settings, thrombosis is clinically less relevant.11For mitral bioprostheses, despite the absence of dedicated studies, older reports in a setting with lower flow have suggested that the rate of thromboembolic events is low (about 3%).12 However it is likely that some peripheral thromboembolic episodes went undetected; therefore, the true embolic rate is probably higher. Moreover, emboli caused permanent disability or death in 42% of patients.12 Accordingly, the optimal strategy for patients with no other indication for anticoagulation is unclear, and this is reflected by the great variability of antithrombotic practices. Most centres suggest VKA in the first 3 months followed by low-dose acetylsalicylic acid (ASA) (class IIa of evidence according the 2012 European Society guidelines). The same approach can be defined for tricuspid valve replacement. Patients with mechanical valve should be treated with VKA long term. An add-on low dose of ASA is not routinely suggested. In view of this heterogeneity, we performed a retrospective analysis of a consecutive cohort of patients admitted to an inpatient cardiac rehabilitation facility at the IRCCS Fondazione Don Gnocchi, Milan, Italy, after an early post-operative discharge from cardiac surgery. Among 138 patients, 51 (37%) had AF (including both previously known AF cases and cases that developed as persistent or paroxysmal after the surgical procedure). Thirteen cases involved patients with a mechanical valve. Most of the patients were discharged on VKA. A total of 59 patients (42%) could be discharged on DOAC or aspirin. Whether this approach generated a net clinical benefit is undeterminable. However, the costs of this approach are clear, as is the necessity to organize coagulation monitoring and optimize target INR stability. Following these considerations, we have suggested a scheme as an alternative to current guidelines, mostly for patients with barriers to a safe coagulation monitoring (Figure 1). The inpatient cardiac rehabilitation unit could be the ideal setting in which to perform an anticoagulant switch (towards DOAC or aspirin), with timely monitoring of any new AF paroxysm. Moreover, cardiac rehabilitation could serve as the setting for educating patients on self-monitoring through point-of-care tests (POC), as medical devices to be implemented at home. Antithrombotic therapy following cardiac surgery. AKA, acetylsalicylic acid; OAC, oral anticoagulant; POC, point of care; TAVI, transcatheter aortic valve implantation; SAVR, surgical aortic valve replacement; VKA, vitamin K antagonist. Surgical left atrial appendage occlusion should also be strongly considered for further reduction of stroke risk. Managing antithrombotic risk is a cornerstore of the treatment of post-cardiac surgery patients, and the balance between haemorrhagic and thrombotic risk is fragile. Accordingly, we suggest a uniform strategy, using a considerably safer, manageable approach that is already supported by the literature. In addition, the heterogeneity of indications for antithrombotic treatment after cardiac surgery clearly makes inpatient cardiac rehabilitation the ideal setting to safely bridge patients home after a surgical cardiac procedure, ensuring optimally tailored and cost-effective anticoagulation. N.M. designed the study. S.D.L. and I.C. contributed to the letter. L.T., A.R., and S.B. revised the protocol critically for important intellectual content, and all the authors approved the final manuscript. This work was supported by the Italian Ministry of Health (‘Ricerca Corrente’). Data are available upon request to the corresponding author.

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