Ep 166: A 64-Year-Old with Fatigue, Difficulty Sleeping, and Dyspnea on Exertion

This episode reviews the diagnosis and acute management of tachycardia.

Read more on this topic in Harrison's.

Harrison's Principles of Internal Medicine, 22nd Edition

Transcript

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[Ms. Heidhausen] This is Katarina Heidhausen, executive editor of Harrison's Principles of Internal Medicine. Harrison's Podclass is brought to you by McGraw Hill's AccessMedicine, the online medical resource that delivers the latest content from the best minds in medicine. And now, on to the episode. 

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[Dr. Handy] Hi, everyone. Welcome back to Harrison's Podclass. We're your co-hosts. I'm Dr. Cathy Handy. 

[Dr. Wiener] And I'm Dr. Charlie Wiener, and we're joining you from the Johns Hopkins School of Medicine. 

[Dr. Handy] Today's episode is a 64-year-old with fatigue, difficulty sleeping, and dyspnea on exertion. 

[Dr. Wiener] Cathy, today's patient is a 64-year-old man who presents to your office saying he has not felt well for the past five to seven days. He has a history of hypertension and diabetes that have been well controlled with hydrochlorothiazide, losartan, and metformin. He reports increasing fatigue, poor sleep, and dyspnea on exertion over the past week or so. He also feels like his heart has been racing even when he is at rest. He denies any fevers, tremors, loss of consciousness, or neurologic symptoms. He does not smoke or drink alcohol, and he works remotely as a buyer for an electronics store. He was last in the office about four months ago, and his physical examination and screening labs then were normal. 

[Dr. Handy] And his physical examination now? 

[Dr. Wiener] He has a heart rate of 100 to 110, that's irregularly irregular. His blood pressure's 110/70. Respirations and oxygenation are normal. You see no significant jugular venous distention. He has no murmurs, but his cardiac sounds are irregular. He has no lung crackles. His abdomen is normal. He has no pitting edema, and his neurologic exam is nonfocal. 

[Dr. Handy] Sounds like he has new atrial fibrillation. Can I have an EKG? 

[Dr. Wiener] You bet, and you're right. He has new atrial fibrillation compared to an ECG four months ago. There are no acute ST-T wave changes, and his heart rate is consistently over 100 on today's tracing. 

[Dr. Handy] Okay, he has new AFib, and you did mention some risk factors that he has, too. 

[Dr. Wiener] Tell me more about risk factors. 

[Dr. Handy] Atrial fibrillation, or Afib, is the most common sustained arrhythmia in adults and is a major public health issue. The prevalence increases with age with over 95% of atrial fibrillation patients over the age of 60. The prevalence in people over 80 is about 20%. And the lifetime risk of developing AFib for men over 40 years old is about 25%. 

[Dr. Wiener] I think we've all seen lots of AFib; it's common. What are the risk factors? 

[Dr. Handy] The risk factors for developing AFib in addition to age and underlying cardiac disease are hypertension, diabetes, a family history, obesity, thyroid disease, and sleep-disordered breathing. Our patient has two of these, and we should also check his thyroid function. 

[Dr. Wiener] You say AFib is a public health issue. Why? 

[Dr. Handy] It's not a benign condition. AFib carries a 1.5 to 1.9-fold increased risk of mortality after controlling for underlying cardiac disease. The most important consequence of AFib is a significantly increased risk of stroke compared to the general population. Estimates are that it's responsible for about 25% of all strokes. Patients with AFib are also at higher risk of developing dementia and cardiomyopathy. 

[Dr. Wiener] Good review. Let's get to our question for today which is going to focus on the acute management of this patient. The question asks, which of the following is the best next step for this patient? Option A. admit to the hospital to start ibutilide. Option B. start a beta blocker and follow up in three to five days. Option C. start enoxaparin and follow up in three to five days. Option D. start a beta blocker and enoxaparin with planned cardioversion in three weeks. Or option E. transfer to the nearest emergency department for immediate cardioversion. 

[Dr. Handy] Okay, so we're talking here only about acute management. We'll discuss chronic AFib therapy in a future episode. 

[Dr. Wiener] Noted. 

[Dr. Handy] The treatment and management of the patient with AFib centers on three important aims. One, control of patient's symptoms through a strategy of rate control or rhythm control. Two, appropriate mitigation of the thromboembolism risk. And three, addressing modifiable risk factors for progression of Afib. In the acute onset of Afib, if there is significant hemodynamic compromise, pulmonary edema or evidence of coronary ischemia, emergent cardioversion is recommended. 

[Dr. Wiener] So option E. proposed emergent cardioversion. 

[Dr. Handy] Well, for this patient, I don't think that that's necessary. He's not in shock. His lungs were clear, and his ECG did not show any acute ischemia, so option E. is out. 

[Dr. Wiener] Okay, where are you going to go next? 

[Dr. Handy] Since our patient is hemodynamically stable, the therapy should focus on control of the ventricular rate to prevent hemodynamic sequelae. The goal of rate control in AFib is to allow more diastolic filling time and that improves cardiac output and reduces patient symptoms. In the longer term, adequate rate control will minimize the risk of congestive heart failure and tachycardia-induced cardiomyopathy. For this patient, acute rate control could be with a beta blocker or a calcium channel blocker. 

[Dr. Wiener] Okay. Well, options B. and D. both suggest a beta blocker with a difference being whether or not to use enoxaparin. 

[Dr. Handy] Since this patient has presumed new AFib, it is worth trying to cardiovert him into sinus rhythm, but there's a caveat. Although there's a lack of definitive data, it is presumed that if the presenting episode of AFib is over 48 hours, or if the episode duration is unknown, there's a risk for precipitating a thromboembolic complication through either electrical or pharmacologically achieved cardioversion. And our patient has had symptoms for a week, therefore, he should be either initiated on anticoagulation with cardioversion deferred for at least three weeks after uninterrupted anticoagulation, or evaluated to exclude the presence of a left atrial appendage thrombus. 

[Dr. Wiener] Okay, so that means our answer is D. We're going to start him on beta blocker and enoxaparin and cardiovert in three weeks. What about the option of excluding the presence of a left atrial appendage thrombus right now? 

[Dr. Handy] The major source of thromboembolism and stroke in non-valvular AFib is formation of thrombus in the left atrial appendage, where flow is relatively stagnant. Following conversion from prolonged AFib to sinus rhythm, atrial mechanical function can be delayed for weeks, so-called atrial stunning, such that thrombi can form even during sinus rhythm. Most commonly, transesophageal echocardiography is used to evaluate for left atrial appendage thrombus, although cardiac computed tomography angiography has been demonstrated to have excellent sensitivity and specificity as well. But remember, even if thrombus is not present, the patient should have at least four weeks of anticoagulation after the cardioversion because of the stunning risk. 

[Dr. Wiener] What about long-term anticoagulation? 

[Dr. Handy] Again, a future topic that we can talk about on another episode, but the short answer is that maintenance of anticoagulation is considered based on the patient's individual risk for stroke; that's commonly assessed using the CHADS2-VASc score. 

[Dr. Wiener] So option A. mentioned ibutilide. Tell me about that. 

[Dr. Handy] It's a class III antiarrhythmic that's used for pharmacologic cardioversion. Ibutilide should be avoided in patients with baseline prolonged QT interval or severe left ventricular dysfunction, given the risk of Torsades de Pointes. And that option was not ideal for our patient because his duration of presumed AFib warrants anticoagulation. 

[Dr. Wiener] Great, so the teaching points in today's case are that the development of atrial fibrillation is a common event in older patients with underlying cardiac disease, hypertension, or diabetes. In a hemodynamically stable patient, the acute management relies on rate control for symptoms and considerations of anticoagulation to lessen the risk of stroke, particularly if cardioversion to a sinus rhythm is being considered. 

[Dr. Handy] And you can find this question and other questions like it in the Harrison's Self-Review book. And you can learn more about this topic in the Harrison's chapter, called Atrial Fibrillation. Visit the show notes for links to helpful resources, including related chapters and review questions from Harrison's, available exclusively on AccessMedicine. If you enjoyed this episode, please leave us a review, so we can reach more listeners just like you. Thanks so much for listening. 

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