[intro music]
[Dr. Handy] Hi, welcome to Harrison's Podclass where we discuss important concepts in internal medicine. I'm Cathy Handy. [Dr. Wiener] And I'm Charlie Wiener and we're coming to you from the Johns Hopkins School of Medicine. Welcome to Harrison's Podclass. Today's case is a 24-year-old with palpitations. Morning, Cathy. [Dr. Handy] Hey Charlie. [Dr. Wiener] Okay so here today, we have a 24-year-old woman, comes to your office to establish primary care.
She recently immigrated from Myanmar to start graduate school in your city. She grew up in a rural environment and was generally healthy, although her mother told her she had rheumatic disease as a child. She did not get any ongoing medical care in Myanmar, and she's never had any other episodes. On review of systems, she does note that a few times a week, she feels her heart racing and that it seems irregular.
These episodes can start most any time, but are more common during stress or exercise. If she's exercising and one of these episodes starts, she notes that she gets very short of breath. They abate as she calms herself down by doing meditation. So based on that history, what do you think, Cathy? [Dr. Handy] While not prevalent in the United States, rheumatic heart disease is still a worldwide issue, and that component of our history should not be ignored. [Dr. Wiener] What do you mean?
[Dr. Handy] Well, rheumatic heart disease can have long term consequences, so even though many people will get it as a child, adult practitioners do need to be aware of it. [Dr. Wiener] What things are you worried about and what specifically piques your interest in this case?
[Dr. Handy] So it would predispose her to valvular problems, such as mitral stenosis, arrhythmias, most notably atrial fibrillation, which could be contributing to her symptoms now, and she'll need to be evaluated for prophylactic antibiotics for procedures. Actually, the history that she gives does sound suspicious for paroxysmal or sustained atrial fibrillation. Do you have her vital signs? [Dr. Wiener] Yeah, she's afebrile, her heart rate is 96, but it is irregularly irregular.
Her blood pressure's 110 over 65, her respiratory rate is 12, and her oxygen saturation is 98% on room air. [Dr. Handy] And physical exam, in particular the cardiac exam? [Dr. Wiener] Well, she has normal jugular venous pressure, but on cardiac auscultation, you hear a loud S1, and a soft opening snap after S2, that is associated with a low-pitched early diastolic murmur that is heard best at the apex. The rest of her physical examination is relatively unremarkable.
She has clear lungs and no pedal edema. [Dr. Handy] Okay, so the irregularly irregular heart rhythm you described is classic for atrial fibrillation, and the murmur that you described is what you would expect in someone with mitral stenosis. What's the question being asked? [Dr. Wiener] Okay, so the question asks, you calculate her CHA2DS2-VASc score as one. you calculate her CHA2DS2-VASc score as one. She gets one point for female sex characteristics.
[Dr. Handy] Well, let me just stop you for a moment, because that score really wouldn't apply to her. [Dr. Wiener] What do you mean, why not? I thought that's how we determine risk for anticoagulation in patients with atrial fibrillation. [Dr. Handy] So patients with atrial fibrillation are at an increased risk for embolic stroke, which is why we think about anticoagulation in these patients.
The CHA2DS2-VASc score quantifies the risk for patients with common non-valvular atrial fibrillation, and helps decide who should receive stroke prophylaxis based on the score. The score gives points for the presence of congestive heart failure, hypertension, age, a history of prior stroke or TIA, diabetes, vascular disease or sex, and a higher score is associated with a higher risk of embolic stroke, and most people recommend treatment in patients who are really anything other than low risk.
But I will note that women receive a point in the system just based on sex alone. [Dr. Wiener] So why do you say she does not fit into this category and why should we not be using this score on her? [Dr. Handy] She has valvular atrial fibrillation from her mitral stenosis. Now, anticoagulation is warranted for patients with mitral stenosis, hypertrophic cardiomyopathy, and those with a prior history of stroke, really regardless of this score.
[Dr. Wiener] Okay, so the question goes on to ask, which of the following represents the appropriate approach to stroke prevention in this patient? And the options are, A. arrange for immediate cardioversion into sinus rhythm; B. arrange amiodarone orally and one week later arrange an electrical cardioversion; C. initiate aspirin 325 milligrams daily; D. initiate apixaban five milligrams twice daily; or E. initiate warfarin.
Some of these, based on what you already said, can be ruled out, but let's go through them. [Dr. Handy] Okay, so immediate cardioversion and amiodarone can be ruled out, those would not be applicable here and we want to talk about anticoagulation. The other three choices are all related to some sort of anticoagulation, so let's talk about those. [Dr. Wiener] Well, warfarin can be a pain for patients to take and monitor. Would you go with that, aspirin or apixaban?
[Dr. Handy] I would go with warfarin, and that's the correct answer in this case. Anti-platelet agents, such as aspirin, alone are generally not sufficient, so we can rule that out, and apixaban is used for atrial fibrillation, but would not be used in this patient. [Dr. Wiener] Why not?
[Dr. Handy] The major options for anticoagulation in non-valvular atrial fibrillation are the antithrombin inhibitors, dabigatran, the factor Xa inhibitors, such as rivaroxaban, apixaban and edoxaban, and the vitamin K antagonist warfarin. In non-valvular atrial fibrillation, warfarin has been shown to reduce the annual risk of stroke by 64% compared to placebo, and by 37% compared to anti-platelet therapy.
Patients with atrial fibrillation with an increased risk of stroke also have an increased risk of venous thromboembolism which appears to be lower with oral anticoagulation.
Now, the direct acting anticoagulants like dabigatran, rivaroxaban, apixaban, which is mentioned in this case, and edoxaban, were non-inferior to warfarin in individual trials, and analysis of pooled data suggests superiority to warfarin by absolute margins of less than 1% in reduction of mortality, stroke, major bleeding and intracranial hemorrhage. But remember, those are patients with non-valvular atrial fibrillation.
[Dr. Wiener] So what about this patient who has valvular disease and atrial fibrillation? [Dr. Handy] Warfarin is the agent recommended for patients with rheumatic mitral stenosis or mechanical heart valves. The newer direct-acting anticoagulants have not been tested in rheumatic heart disease, and a direct thrombin inhibitor did not prevent thromboemboli in patients with mechanical heart valves. So that's why this patient would be started on warfarin, and not one of the newer agents.
[Dr. Wiener] Okay great, so the teaching point in this case, are that patients with atrial fibrillation are at increased risk of embolic stroke. Deciding which medications should be used to reduce the risk of stroke depends on whether or not the patient has valvular heart disease or non-valvular heart disease. In the absence of valvular heart disease, the patient's level of risk can be assessed using the CHADS2-VASc score.
In patients with valvular heart disease and atrial fibrillation, they should receive warfarin. [Dr. Handy] And you can read more about this in Harrison's chapter on atrial fibrillation. [outro music] [Mr. Shanahan] This is Jim Shanahan, publisher at McGraw Hill. Harrison's Podclass is brought to you by McGraw Hill's Access Medicine, the online medical resource that delivers the latest trusted content from the best minds in medicine. Go to accessmedicine.com to learn more.