Antithrombotic therapy in valvular heart disease

Native valve disease in patients with non-valvular atrial fibrillation on warfarin or rivaroxaban

OBJECTIVE

To compare the characteristics and outcomes of patients with atrial fibrillation (AF) and aortic stenosis (AS) with patients with AF with mitral regurgitation (MR) or aortic regurgitation (AR) and patients without significant valve disease (no SVD).

METHODS

Using Rivaroxaban Once-Daily, Oral, Direct Factor Xa Inhibition Compared With Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) data, we analysed efficacy and safety outcomes, adjusting hazard ratios (HRs) for potential confounders using Cox regression analysis.

RESULTS

Among 14 119 intention-to-treat ROCKET AF trial patients, a trial that excluded patients with mitral stenosis or artificial valve prosthesis, 214 had AS with or without other valve abnormalities, 1726 had MR or AR and 12 179 had no SVD. After adjusting for prognostic factors, the composite of stroke, systemic embolism or vascular death increased approximately twofold in patients with AS (AS 10.84, MR or AR 4.54 and no SVD 4.31 events per 100 patient-years, p=0.0001). All-cause death also significantly increased (AS 11.22, MR or AR 4.90 and no SVD 4.39 events per 100 patient-years, p=0.0003). Major bleeding occurred more frequently in AS (adjusted HR 1.61, confidence intervals (CI) 1.03 to 2.49, p<0.05) and MR or AR (HR 1.30, 1.07 to 1.57, p<0.01) than in no SVD, but there was no difference between AS and MR or AR (HR 1.24, 0.78 to 1.97). The relative efficacy of rivaroxaban versus warfarin was consistent among patients with and without valvular disease. Rivaroxaban was associated with higher rates of major bleeding than warfarin in patients with MR or AR (HR 1.63, 1.15 to 2.31).

CONCLUSIONS

We found that patients with AF and AS on oral anticoagulants may have distinctly different efficacy and safety outcomes than patients with MR or AR or no SVD.

TRIAL REGISTRATION NUMBER

NCT00403767; Post-results.

The Role of Cardiac Imaging in Stroke Prevention

This article reviews the role of cardiac imaging in stroke prevention, defining how imaging tools can be useful in this field. Cardioembolic sources during atrial fibrillation are discussed. New closure devices can be implanted in the left atrial appendage and routinely monitored with imaging modalities. Acute and chronic left ventricular dysfunction is reviewed, identifying the possible mechanism of thrombus formation and its early detection. Valvular evaluation of native heart disease and possible implications for stroke risk are defined.

Prevention of cardioembolic stroke

Cardiac causes of ischemic stroke lead to severe neurological deficits from large intracranial artery occlusion compared to small vessel ischemic stroke. The most common cause of cardioembolic stroke is atrial fibrillation (AF), which has an increasing incidence with age. AF stroke trials demonstrate that anti-coagulation is superior to anti-platelet therapy in terms of ischemic stroke prevention. Recently, warfarin was compared with dabigatran, an oral, direct thrombin inhibitor, and was found to be at least equally effective in reducing ischemic stroke with less intracranial bleeding risk. Future research is investigating other direct thrombin inhibitors as potential alternatives to warfarin, which has a narrow therapeutic index, requires frequent blood monitoring, has multiple drug interactions, and a higher rate of intracranial bleeding. Other causes of cardioembolic stroke include myocardial infarction, left ventricular thrombus, reduced ejection fraction, valvular abnormalities, and endocarditis. Patent foramen ovale is a common finding on echocardiograms in patients with and without stroke (up to 20% of the population), and it is a controversial source of cryptogenic stroke. The best way to prevent cardioembolic stroke remains early detection and treatment of AF, and treating the underlying stroke mechanism. Cardiac magnetic resonance imaging is an emerging technology and reveals some sources of cardiac embolism missed by echocardiography, and might provide an additional diagnostic tool in investigating cardioembolic stroke.

Stroke prevention in atrial fibrillation and other major cardiac sources of embolism

The frequency of cardioembolic stroke is expected to rise as the general population ages. Much of the increase may be attributed to atrial fibrillation, the most common cause of cardioembolic stroke and one that plays a substantial role in aging adults. Other sources of cardioembolic stroke may include ventricular thrombus from myocardial infarction, heart failure, structural heart defects such as patent foramen ovale (PFO), atrial septal aneurysm, proximal aortic atheroma, valvular heart disease, and endocarditis. Diagnostic studies, such as neuroimaging, ECG, and echocardiography, are helpful in uncovering cardioembolic sources of stroke. Medical therapy is predicated on the underlying mechanism. For example, warfarin may be indicated in certain patients who have atrial fibrillation, atrial, or ventricular thrombi, and PFO with atrial septal aneurysm and cryptogenic stroke in select young patients to prevent stroke. Newer diagnostic technologies, including multidetector CT and cardiac MRI, may be useful to diagnose cardiac causes of stroke when transesophageal echocardiography is indeterminate or cryptogenic stroke is present.

Effect of antithrombotic therapy in patients with mitral stenosis and atrial fibrillation: a sub-analysis of NASPEAF randomized trial

AIMS

The randomized NASPEAF study included non-valvular with prior embolism and mitral stenosis patients in the same group. This is a sub-study to specially focus on the antithrombotic therapy in mitral stenosis.

METHODS AND RESULTS

We analysed 311 patients with mitral stenosis, compared with 175 non-valvular atrial fibrillation patients with prior embolism, stratified by a history of previous embolism and assigned to anticoagulant therapy [target international normalized ratio (INR) = 2.0-3.0] or combined antiplatelet plus moderate intensity anticoagulant therapy. Median follow-up was 2.9 years. Outcomes were fatal and non-fatal embolism, stroke and myocardial infarction, sudden death, and death from bleeding. Combined therapy in mitral stenosis patients, compared with anticoagulant alone therapy, reduced the risk of vascular events by 58.3%. During equal therapy, the outcome annual rates were essentially the same in non-valvular and valvular patients [hazard ratio 0.90 (95% confidence interval 0.37-2.16), P = 0.81]. During anticoagulant alone therapy, the annual event rate in mitral stenosis patients without prior embolism was low (2.5%) and it was very high in patients with prior embolism (6.6%).

CONCLUSION

Combined therapy was effective in mitral stenosis patients. Prior embolism patients are not efficiently protected with anticoagulant alone therapy for an INR of 2.0-3.0.

Outcomes among valvular heart disease patients experiencing ischemic stroke or transient ischemic attack in Olmsted County, Minnesota

OBJECTIVE

To estimate the rates and predictors of survival and recurrence among residents of Olmsted County, Minnesota, who received an Initial diagnosis based on 2-dimensional color Doppler echocardiography of moderate or severe mitral or aortic stenosis or regurgitation and who experienced a first ischemic stroke, transient ischemic attack (TIA), or amaurosis fugax.

PATIENTS AND METHODS

At the Mayo Clinic in Rochester, Minn, we used the resources of the Rochester Epidemiology Project to identify Individuals who met the criteria for inclusion in the study and to verify exclusion criteria. The study included all residents of Olmsted County, Minnesota, who experienced a first Ischemic stroke, TIA, or amaurosis fugax within 30 days of or subsequent to receiving a first-time 2-dimensional color Doppler echocardlography-based diagnosis of moderate or severe mitral or aortic stenosis or regurgitation between January 1, 1985, and December 31, 1992. The Kaplan-Meier product-limit method was used to estimate the rates of subsequent stroke and death after the ischemic stroke, TIA, or amaurosis fugax. The Cox proportional hazards model was used to assess the effect of several potential risk factors on subsequent stroke occurrence and death.

RESULTS

For the 125 patients in the study, the Kaplan-Meier estimates of the risk of death and the risk of stroke at 2-year follow-up were 38.6% (95% confidence interval [CI], 29.9%-47.5%) and 18.5% (95% CI, 10.0%-27.0%), respectively. Compared with the general population, death rates were significantly Increased (standardized mortality ratio = 1.75; 95% CI, 1.38-2.19; P < .001) but rates of subsequent stroke occurrence were not (standardized morbidity ratio = 1.20; 95% CI, 0.75-1.84; P = .40). After adjustment for age, sex, and cardiac comorbidity, neither the type nor severity of valvular heart disease was an independent determinant of survival or subsequent stroke occurrence.

CONCLUSIONS

Patients with mitral or aortic valvular heart disease who experience Ischemic stroke, TIA, or amaurosis fugax have Increased rates of death, but not recurrent stroke, compared with expected rates. Other cardiovascular risk factors are more important determinants of survival In these patients than the type or echocardiographic severity of the valvular heart disease.

Evaluation and management of transient ischemic attack and minor cerebral infarction

After immediate intervention for cerebral infarction or transient ischemic attack (TIA), the primary goal is secondary prevention of future cerebral ischemia and prevention of complications related to the initial ischemic event. The goals of the diagnostic evaluation are to (1) determine potential contributing mechanisms (cardioembolic, large-vessel disease of the extracranial and intracranial vessels, small-vessel disease, coagulation defects, and cryptogenic), (2) identify contributing risk factors (hypertension, hyperlipidemia, tobacco use, diabetes), and (3) complete the evaluation in a cost-effective and safe manner. We provide a sequential approach to the diagnostic evaluation of cerebral infarction or TIA to optimize diagnostic yield of testing, minimize cost and potential harm to the patient, and provide information that will change management. This systematic approach focuses on 6 important questions: (1) Are the symptoms consistent with a cerebral infarction or TIA (versus nonischemic pathology)? (2) Where does the ischemic event localize? (3) What etiologies and mechanisms of cerebral infarction and TIA are possible? (4) What is the prevalence of each potential etiology? (5) What treatments are available for this etiology? (6) What tests and studies are useful to evaluate this etiology?

Dalteparin as periprocedure anticoagulation for patients on warfarin and at high risk of thrombosis

BACKGROUND

Patients taking warfarin and at high risk for thromboembolic complications have traditionally been hospitalized for two to three days to receive standard treatment with intravenous heparin both prior to and following procedures while their international normalized ratio (INR) is subtherapeutic.

OBJECTIVE

To assess the feasibility of protocol implementation for outpatient anticoagulation with low-molecular-weight heparin to eliminate or reduce the length of hospital admission needed solely for anticoagulation.

METHODS

Patients included were receiving warfarin for a prosthetic heart valve, mitral valve disease with atrial fibrillation, or recent episode of venous thromboembolism. Warfarin was discontinued four days prior to the procedure. Subcutaneous dalteparin 200 units/kg was given on the two mornings prior to the procedure and restarted 12-24 hours after the procedure until the INR was in the therapeutic range. Warfarin was reinitiated on the evening of surgery.

RESULTS

Twenty-four patients underwent 26 procedures. There were two minor bleeding complications, and one patient experienced a transient ischemic attack. Patients received a median of five days of dalteparin. The INR returned to the therapeutic range on the median postoperative day 4. All patients avoided two days of hospitalization prior to the procedure (i.e., no patients needed to be admitted preoperatively for anticoagulation). A median of four days would have been required for the sole purpose of postoperative anticoagulation.

CONCLUSIONS

Outpatient perioperative anticoagulation with dalteparin for high-risk patients requiring long-term oral anticoagulation appears feasible and warrants further study.

Antithrombotic therapy in valvular heart disease

Whether antithrombotic therapy in elderly patients differs from that in younger populations depends on whether the risk for such bleeding differs in the elderly. Regarding long-term therapy with warfarin derivatives, evidence shows that there is a difference. The anticoagulation response to warfarin is exaggerated with advancing age. This article discusses antithrombotic therapies for valvular heart disease, including bioprosthetic and mechanical prosthetic heart valves, aspirin and dipyridamole in combination with oral anticoagulant therapy, antiplatelet agents alone or in combination with very low dose warfarin, tilting disk valves, valve position, first-generation valves compared with modern valves, interruption of anticoagulant therapy, and miscellaneous indications for antithrombotic therapy.

Patient self-monitoring of oral anticoagulant therapy: potential benefits and implications for clinical practice

Coumarin derivatives are widely used oral anticoagulants for patients with chronic atrial fibrillation, venous thromboembolism, valvular heart disease, myocardial infarction or a mechanical prosthetic heart valve. Because of the narrow therapeutic window associated with coumarins and the potential for drug interactions, frequent monitoring of anticoagulation is required to maintain the International Normalized Ratio (INR) between 2.0 to 3.5 for most clinical indications. Monitoring of oral anticoagulant therapy is placing a considerable burden on healthcare providers because many patients require life-long treatment with coumarins, and because of an increasing number of elderly patients with conditions that are treated with coumarins. A novel approach that might, in part, address this healthcare need is patient self-monitoring of anticoagulation with a portable coagulometer. Several cohort studies and randomized controlled trials have found that anticoagulation self-monitoring is as good as, or better than, conventional monitoring in a specialized anticoagulation clinic or by a general practitioner. The advantages of anticoagulation self-monitoring include reduced patient inconvenience relating to anticoagulation clinic visits and laboratory monitoring of warfarin therapy, and fewer INR levels outside the therapeutic INR range if INR measurements are preformed more frequently with anticoagulation self-monitoring. Thus, anticoagulation self-monitoring has the potential to reduce the incidence of thromboembolic and bleeding episodes in patients who are receiving long term oral anticoagulant therapy. The potential drawbacks of anticoagulation self-monitoring include the costs of the portable coagulometer. Additionally, self-monitoring is limited to patients who have the cognitive and physical capabilities to perform the technique required for the portable coagulometer.

Predictors of cerebrovascular events and death among patients with valvular heart disease: A population-based study

BACKGROUND AND PURPOSE

There is little population-based information on cerebrovascular events and survival among valvular heart disease patients. We used the Kaplan-Meier product-limit method and the Cox proportional hazards model to determine rates and predictors of cerebrovascular events and death among valve disease patients.

METHODS

This population-based historical cohort study in Olmsted County, Minnesota, reviewed residents with a first echocardiographic diagnosis of mitral stenosis (n=19), mitral regurgitation (n=528), aortic stenosis (n=140), and aortic regurgitation (n=106) between 1985 and 1992.

RESULTS

During 2694 person-years of follow-up, 98 patients developed cerebrovascular events and 356 died. Compared with expected numbers, these observations are significantly elevated, with standardized morbidity ratio of 3.2 (95% CI, 2.6 to 3.8) and 2. 5 (95% CI, 2.2 to 2.7), respectively. Independent predictors of cerebrovascular events were age, atrial fibrillation, and severe aortic stenosis. The risk ratio of severe aortic stenosis was 3.5 (95% CI, 1.4 to 8.6), with atrial fibrillation conferring greater risk at younger age. Predictors of death were age, sex, cerebrovascular events, ischemic heart disease, and congestive heart failure, the greatest risk being among those with both congestive heart failure and cerebrovascular events (risk ratio=8.8; 95% CI, 5. 8 to 13.4). Valve disease type and severity were not independent determinants of death.

CONCLUSIONS

The risk of cerebrovascular events and death among patients with valve disease remains high. Age, atrial fibrillation, and severe aortic stenosis are independent predictors of cerebrovascular events, and age, sex, cerebrovascular events, congestive heart failure, and ischemic heart disease are independent predictors of death in these patients.

A European view on the North American fifth consensus on antithrombotic therapy

An American-Canadian group of experts have, in the November 1998 issue of CHEST, published for the fifth time their recommendations for antithrombotic therapy. This remarkable consensus document was the result of an extensive review of the literature by an interdisciplinary group. Considering the impact of this document on medical practice, also outside North America, a group of European experts reviewed in detail the fifth report, particularly the sections on clinical indications of antithrombotic treatment. The aim was not to indicate the many areas of agreement and to quote literature that has become available since publication of the last consensus documents, but rather to refer to the gray zones of uncertainty and limited number of divergent opinions.

Antithrombotic therapy for valve disease: native and prosthetic valves

The use of antithrombotic agents to prevent thromboembolic events in patients with valvular heart disease is common. Recent studies using improved diagnostic techniques have allowed better elucidation of valvular abnormalities and re-evaluated the incidence and risk of thromboembolism. We review the recent literature examining the risk of thromboembolic events in various valvular abnormalities, and the use of different antithrombotic agents in the prevention of thromboembolic events. We also review the current recommended practice in both native valve abnormalities and prosthetic heart valves.