MKSAP quiz on telemetry

The following cases and commentary, which focus on the use of telemetry, are excerpted from ACP's Medical Knowledge Self-Assessment Program (MKSAP 15).

Case 1: Syncope and tachycardia

A 40-year-old man is admitted to the hospital after an episode of syncope at work. He has had a 1-week history of progressive shortness of breath, orthopnea, and fatigue. On admission he is found to be hypotensive and is started on intravenous dopamine. Echocardiogram shows dilated left and right ventricles with a left ventricular ejection fraction of 10% and no regional wall motion abnormalities. Telemetry shows frequent and prolonged runs of nonsustained ventricular tachycardia. He has no other medical problems and takes no medications.

On physical examination, he is afebrile. Blood pressure is 70 mm Hg systolic, pulse is 110/min, and respiration rate is 20/min. The jugular veins are distended. Heart rate is regular, and a summation gallop is noted. There is no rash or skin lesions. Extremities are cool with no edema. Laboratory studies show a serum troponin level of 5 ng/mL (5 µg/L). Chest radiograph shows mild cardiomegaly and pulmonary edema and no other abnormalities. Electrocardiogram shows sinus tachycardia, normal QRS duration, and frequent premature ventricular complexes. Cardiac catheterization after admission shows normal coronary arteries.

Which of the following is the most appropriate management step?

A. Biventricular pacemaker placement
B. Cardiac MRI
C. Endomyocardial biopsy
D. Implantable defibrillator placement

View correct answer for Case 1

Case 2: Chest pain

A 45-year-old man is evaluated in the emergency department for a 2-day history of substernal sharp intermittent chest pain that is aggravated by deep breaths. He began experiencing severe chest pain 4 hours prior to his emergency department visit. He has a 3-day history of nonproductive cough, sore throat, myalgias, and malaise. He has had hypertension for 12 years. His medications are hydrochlorothiazide and amlodipine.

On physical examination, temperature is 37.8°C (100.0°F), blood pressure is 168/100 mm Hg, pulse is 110/min, and respiration rate is 26/min. Oxygen saturation on ambient air is 96%. The patient's face and chest appear diaphoretic. The oropharynx is erythematous. There is no jugular venous distention and no hepatojugular reflux. Cardiac examination discloses a two-component rub that is loudest at the apex, distant heart sounds, and no murmurs. Pulmonary examination discloses normal breath sounds and no crackles. There is no palpable chest wall tenderness. Laboratory studies show a leukocyte count of 12,300/µL (12.3 × 109/L) with 50% polymorphonuclear cells, 30% lymphocytes, and no band forms. Initial serum troponin T level is 0.6 ng/mL (0.6 µg/L). Twelve-lead electrocardiogram shows sinus tachycardia and concave upward ST-segment elevation in leads V1 through V6. Chest radiograph shows no infiltrates and a normal cardiac silhouette.

Which of the following is the most likely diagnosis?

A. Acute myocardial infarction
B. Acute viral pericarditis
C. Costochondritis
D. Pleuritis
E. Pulmonary embolism

View correct answer for Case 2

Case 3: Woman with chest pressure

A 45-year-old woman is admitted to the hospital for evaluation of a 6-week history of progressive, dull chest pressure associated with mild dyspnea and nausea. At onset, the chest pain occurred during physical exertion (housework) and was relieved by rest within 5 minutes. For the past several days, the patient has had similar episodes that occurred with minimal activity, such as walking, and also at rest, including an episode this morning, which she described as 8/10 in severity of the pain and lasted for 10 to 15 minutes. The chest discomfort is not pleuritic or positional and is not related to eating. She has hypertension, treated for the past 6 years, and systemic lupus erythematosus for 24 years, with a history of pericarditis, arthritis, and a photosensitive facial rash. Her medications include prednisone, hydroxychloroquine, aspirin, and enalapril.

On physical examination, she is afebrile, blood pressure is 132/78 mm Hg, pulse is 86/min, and respiration rate is 18/min. Oxygen saturation on ambient air is 98%. BMI is 25. Her lungs are clear to auscultation. Estimated central venous pressure is normal; there is no Kussmaul sign or hepatojugular reflux. Cardiac auscultation reveals regular rhythm with normal S1 and S2 and no murmur, rub, or gallop.

Laboratory studies show erythrocyte sedimentation rate 39 mm/h, creatine kinase 65 U/L, creatine kinase MB fraction 3%, and troponin T 0.04 ng/mL (0.04 µg/L).

Electrocardiogram demonstrates sinus rhythm, with a rate of 92/min. There are symmetric T-wave inversions in leads V1 through V4; there is no ST-segment depression or elevation. Chest radiograph shows a normal cardiac silhouette with no infiltrate or edema.

Which of the following diagnostic tests is most appropriate at this time?

A. Coronary angiography
B. Exercise stress echocardiogram
C. High-sensitivity C-reactive protein level
D. Transthoracic echocardiography

View correct answer for Case 3

Case 4: Repeated syncope

A 35-year-old black woman is admitted to the hospital after experiencing two episodes of syncope in the same day. The episodes were brought on by standing, with abrupt loss of consciousness for 5 minutes. There were no prodromal symptoms and the episodes were nonexertional. She had no associated nausea, vomiting, diaphoresis, or postictal confusion. She has had a 12-month history of chest pain, cough, and dyspnea. Exercise thallium stress testing done 2 months ago demonstrated patchy uptake of radionuclide throughout the ventricular myocardium and no demonstrable ischemia. Her mother died suddenly at age 45 years.

On physical examination, the patient is afebrile, blood pressure is 110/60 mm Hg without orthostasis, pulse is 65/min, and respiration is unlabored at a rate of 16/min. Yellowish-brown maculopapular lesions are present around the lips and eyelids. Jugular veins are distended. Pulmonary auscultation reveals faint scattered expiratory wheezes. Cardiac examination discloses normal heart sounds with no murmurs or gallops. Trace pedal edema is noted.

Twelve-lead electrocardiogram shows sinus rhythm, first-degree atrioventricular block, and left bundle branch block. Chest radiograph shows hilar lymphadenopathy and scattered interstitial infiltrates. Twenty-four-hour electrocardiographic monitoring shows frequent premature ventricular ectopic beats and nonsustained ventricular tachycardia. Endomyocardial biopsy discloses noncaseating granulomata.

Which of the following is the most appropriate management option?

A. Amiodarone
B. Cardiac magnetic resonance imaging
C. Electrophysiologic study
D. Implantable cardioverter-defibrillator placement
E. Implantation of permanent pacemaker

View correct answer for Case 4

Answers and commentary

Case 1

Correct answer: C. Endomyocardial biopsy.

This patient presents with a new-onset, unexplained, hemodynamically significant heart failure. Although endomyocardial biopsy is generally not indicated in the evaluation of heart disease, it may prove critical in diagnosing unusual conditions, such as giant cell myocarditis, in which a histologic diagnosis dictates management. Endomyocardial biopsy is recommended in patients with new-onset heart failure (<2 weeks) with hemodynamic compromise and in those with new-onset heart failure of 2 weeks' to 3 months' duration associated with a dilated left ventricle and new ventricular arrhythmias, Mobitz type II second- or third-degree atrioventricular heart block, or failure to respond to usual care within 1 to 2 weeks. Giant cell myocarditis is a rare, idiopathic cause of fulminant or subacute-onset heart failure. Most patients with giant cell myocarditis present with heart failure (75%), but a substantial minority may present with ventricular arrhythmia (14%) or heart block (5%). Diagnosis is made by endomyocardial biopsy and is characterized by the presence of multinucleated giant cells with eosinophils and myocyte necrosis. Prognosis is very poor, and urgent evaluation for cardiac transplantation is recommended, although giant cell myocarditis can recur in the transplanted heart.

Patients with giant cell myocarditis may be so hemodynamically unstable and are generally felt to have such a poor prognosis that implantation of a ventricular assist device may be necessary as a bridge to cardiac transplantation. Given the rarity of the disease and significant survivor bias in published series and case reports, there are no large randomized prospective trials to provide definitive guidance regarding immunosuppressive therapy; currently, practice varies by center.

A biventricular pacemaker is indicated for treatment of patients with left ventricular ejection fraction less than or equal to 35%, QRS duration 120 msec or greater, sinus rhythm, and New York Heart Association (NYHA) class III or IV symptoms (that is, symptoms with mild activity or at rest) on optimal medical therapy for heart failure. Although this patient does have a reduced ejection fraction and NYHA class IV symptoms, he does not meet the other criteria of a prolonged QRS duration and being on optimal medical therapy. In any case, the patient's hemodynamic instability precludes this elective or semi-elective procedure.

Cardiac MRI can be useful in diagnosing infiltrative or inflammatory cardiomyopathies. In this case, however, the patient is too unstable to undergo MRI. In addition, given the clinical suspicion for giant cell myocarditis, endomyocardial biopsy is the gold standard for diagnosis. Endomyocardial biopsy can be performed in the cardiac catheterization laboratory, where personnel and resources are available for management of cardiogenic shock. If necessary, endomyocardial biopsy can also be performed at bedside under transthoracic echocardiographic guidance.

An implantable defibrillator is indicated for hemodynamically significant ventricular arrhythmias in the setting of reduced ejection fraction. This patient's ventricular arrhythmias and hemodynamic instability are likely the result of an underlying acute cardiomyopathic process (giant cell myocarditis) that requires urgent treatment with cardiac transplantation, possibly preceded by ventricular assist device implantation. In addition, the patient's extreme instability precludes any sort of elective or semi-elective procedure such as an implantable defibrillator placement, and in a case such as this, an implantable defibrillator would only induce repeated shocks without treating the underlying disease process.

Key Point

  • Endomyocardial biopsy is recommended in patients with new-onset heart failure (>2 weeks) and hemodynamic compromise.

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Case 2

Correct answer: B. Acute viral pericarditis.

Specific history and, occasionally, physical examination findings are essential in guiding the diagnostic evaluation of patients who present with severe chest pain, which may signify potentially life-threatening illnesses. Acute viral pericarditis is the most likely diagnosis in this patient who presents with constitutional symptoms (myalgias, malaise), pleuritic chest pain, low-grade fever, pericardial friction rub, lymphocytosis, and ST-segment elevation. Although unusual, the serum troponin level or the MB fraction of creatine kinase may be modestly elevated, indicative of epicardial inflammation.

An acute myocardial infarction is a possible diagnosis in a patient with chest pain, ST-segment elevation, and risk factors for coronary artery disease that include diabetes mellitus, hypertension, tobacco use, and illicit drug use. However, ST-segment elevation in acute myocardial infarction is typically concave downward and not upward, as in this patient. In addition, myocardial infarction would not explain this patient's constitutional symptoms, pericardial friction rub, and lymphocytosis.

Costochondritis is a classic cause of pleuritic chest pain. It is associated with reproducible pain with palpation of the upper costal cartilages at the costochondral or costosternal junctions. However, this diagnosis is unlikely in this patient given the lack of palpable chest wall tenderness and the presence of ST-segment elevation, constitutional symptoms, friction rub, elevated troponin level, and febrile illness.

A viral pleuritis could account for many of this patient's symptoms, such as pleuritic chest pain, low-grade fever, constitutional symptoms, and lymphocytosis. However, it would not explain a pericardial friction rub, elevated troponin level, or ST-segment elevation.

Pulmonary embolism may cause pleuritic chest pain and should be considered in this patient. However, the constitutional symptoms prior to the onset of chest pain would not be explained by this etiology. In addition, ST-segment elevation, pericardial friction rub, and an elevated troponin level would not be expected on the basis of pulmonary embolism.

Key Point

  • Acute viral pericarditis is typically characterized by pleuritic chest pain, fever, pericardial friction rub, lymphocytosis, and ST-segment elevation.

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Case 3

Correct answer: A. Coronary angiography.

The patient is a young woman with hypertension but no other traditional risk factors for coronary heart disease. However, she has a long history of systemic lupus erythematosus, which is an autoimmune inflammatory disease. Inflammation is a possible mechanism of vascular endothelial injury and may promote the development of atherosclerotic disease. Coronary artery disease is a major cause of premature death in patients with systemic lupus erythematosus, and atherosclerosis has been found to develop prematurely in this disease. In addition, persons with systemic lupus erythematosus may have other cardiac involvement including pericardial disease (acute or recurrent pericarditis, pericardial effusion and tamponade, constrictive pericarditis), myocarditis, cardiomyopathy, and valvular regurgitation due to noninfective endocarditis.

The patient's presenting symptoms are typical of unstable angina: the pain is new in onset, progressive, and occurs with minimal activity or at rest. In light of the severity of her symptoms, electrocardiographic abnormalities consistent with ischemia (probably in the distribution of the proximal left anterior descending coronary artery), and the indeterminate troponin T level, coronary angiography and possible revascularization are indicated. Exercise stress echocardiography should not be performed because of her unstable symptoms and her high pretest probability of coronary artery disease.

High-sensitivity C-reactive protein level, a nonspecific biomarker of inflammation, would likely be abnormally elevated in this patient with systemic lupus erythematosus and is not diagnostically useful in this setting. In fact, this test, which is often used to assess ongoing inflammation as a predictor of future risk of cardiovascular events, is not valid in the setting of recent infection or chronic inflammatory conditions.

Transthoracic echocardiography is not indicated for this patient. Although she has a history of pericarditis, her symptoms, examination findings, and electrocardiographic findings are not consistent with either recurrent pericarditis or constrictive pericarditis. Acute pericarditis is associated with sharp, pleuritic, positional chest pain and diffuse ST-segment and T-wave abnormalities not in a distribution consistent with a coronary artery territory.

Key Point

  • Chronic inflammatory conditions, such as systemic lupus erythematosus, may be associated with cardiac complications, including premature atherosclerotic coronary artery disease.

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Case 4

Correct answer: D. Implantable cardioverter-defibrillator placement.

This patient has a probable family history of sudden cardiac death, and her recurrent episodes of syncope are consistent with a cardiac etiology, as evidenced by the lack of associated prodromal symptoms and no evidence of seizure activity. Jugular venous distention and pedal edema are consistent with right-sided heart decompensation. Furthermore, electrocardiography shows conduction abnormalities, and 24-hour monitoring demonstrates ventricular ectopy and nonsustained ventricular tachycardia. A prior thallium stress test showed no ischemia but did reveal patchy myocardial uptake. This is a nonspecific finding but can be seen in cardiac sarcoidosis. Further findings support a clinical diagnosis of sarcoidosis in this patient, namely the maculopapular eruptions and chest radiograph findings of hilar lymphadenopathy and infiltrates. Endomyocardial biopsy findings of noncaseating granulomata confirm cardiac sarcoidosis.

Young black women have an apparent increased frequency for sarcoidosis as compared with other race and/or sex cohorts. Thus, this patient's race, sex, and age are characteristic for patients who more commonly present with sarcoidosis. Sudden death accounts for up to 65% of deaths due to cardiac sarcoidosis, presumably caused by ventricular tachyarrhythmias or conduction block. Symptomatic or electrocardiographically evident arrhythmias or conduction abnormalities typically become evident prior to sudden cardiac death. This patient's history of recurrent syncope, ventricular tachycardia, conduction abnormalities, and family history of sudden death place her at high risk for sudden death. The most appropriate management for this patient is placement of an implantable cardioverter-defibrillator (ICD), which has defibrillation and pacing capabilities for treatment of ventricular tachyarrhythmias and bradyarrhythmias, respectively.

Amiodarone has not been shown to effectively reduce the incidence of sudden cardiac death. Thus, as an isolated agent it does not have a role in prophylaxis of sudden death. However, in patients with an ICD, amiodarone can be used to reduce the frequency of episodes of ventricular tachycardia and subsequent firing of the ICD.

Cardiac magnetic resonance (CMR) imaging is useful for detection of localized myocardial high-intensity areas due to cardiac sarcoidosis and, when performed with late gadolinium enhancement, has a reported sensitivity of 100% and specificity of 78% for the disease. In this patient with confirmed cardiac sarcoidosis by endomyocardial biopsy, however, CMR imaging is not indicated. CMR imaging is a useful screening technique, but owing to the possibility of false-positive results, biopsy may still be necessary to determine the need for an ICD.

Electrophysiologic testing identifies patients with cardiac sarcoidosis who are likely to have sustained ventricular tachyarrhythmias or sudden death. However, such testing should be reserved for those patients who are stratified prior to testing in an intermediate-risk group. This patient is at high risk for sudden cardiac death based on documented cardiac involvement from sarcoidosis, syncope, nonsustained ventricular tachycardia on 24-hour ambulatory monitoring, and family history of sudden death. Thus, a negative electrophysiologic study would likely be a false negative and, therefore, would not obviate the need for an ICD.

A permanent pacemaker would not protect against sudden death from ventricular tachyarrhythmias and thus would not be sufficient treatment for this patient.

Key Point

  • The most appropriate management for patients with cardiac sarcoidosis who are at high risk for sudden death is placement of an implantable cardioverter-defibrillator.