Case 1: Chest pain, negative troponin
A 60-year-old man is evaluated in the hospital for a 2-day history of intermittent chest pain and dyspnea on exertion. Medical history is significant for type 2 diabetes mellitus, hypertension, hyperlipidemia, COPD, and peripheral neuropathy. His ability to exercise is limited by his COPD. Medications are metformin, simvastatin, low-dose aspirin, lisinopril, amlodipine, and an albuterol-ipratropium inhaler.
On physical examination, temperature is normal, blood pressure is 128/78 mm Hg, pulse rate is 80/min, and respiration rate is 16/min. Oxygen saturation is 94% breathing ambient air. Pulmonary examination reveals expiratory wheezing bilaterally. Heart sounds are distant. No edema is present.
Serial serum troponin I measurements are negative.
An electrocardiogram demonstrates left ventricular hypertrophy with repolarization abnormalities.
Which of the following is the most appropriate diagnostic test to perform next?
A. Adenosine single-photon emission CT
B. Coronary angiography
C. Coronary CT angiography
D. Exercise electrocardiography
Case 2: Elevated troponin, normal arteries
A 68-year-old woman is evaluated in the emergency department for acute-onset dyspnea, palpitations, and chest pain. The symptoms began shortly after her dog was attacked by another dog. She is otherwise healthy and takes no medications.
On physical examination, the patient is afebrile, blood pressure is 150/78 mm Hg, and pulse rate is 88/min. Cardiac examination reveals no evidence of increased central venous pressure. There is no heart murmur, but an S3 is present. The lungs are clear to auscultation.
Laboratory studies are significant for a serum troponin I level of 5.2 ng/mL (5.2 µg/L).
An electrocardiogram demonstrates sinus rhythm and anterior hyperacute T-wave elevations suggestive of an ST-elevation myocardial infarction. Cardiac catheterization shows normal coronary arteries. Systolic (left panel) and diastolic (right panel) images from left ventriculography are shown.
Which of the following is the most likely diagnosis?
A. Acute myocarditis
B. Giant cell myocarditis
C. Tachycardia-mediated cardiomyopathy
D. Takotsubo cardiomyopathy
Case 3: Multiple pain episodes at rest
A 69-year-old man is evaluated in the hospital for four episodes of chest pain at rest in the past 24 hours. Medical history is significant for hyperlipidemia, hypertension, tobacco use, and previous transient ischemic attack. Medications are aspirin, hydrochlorothiazide, atorvastatin, and ramipril.
On physical examination, vital signs are normal. The remainder of the examination is unremarkable.
Laboratory studies are notable for normal serum troponin levels.
An electrocardiogram demonstrates 2-mm ST-segment depressions in leads V4 through V6.
Metoprolol, nitrates, clopidogrel, and heparin are initiated.
Which of the following is the most appropriate management?
A. Adenosine nuclear stress testing
B. Coronary CT angiography
C. Exercise stress electrocardiography
D. Urgent angiography
Case 4: Arrhythmia and elevated troponin
A 68-year-old woman is evaluated in the emergency department for a 1-hour history of chest pain. Medical history is significant for hypertension and a 20-year history of type 2 diabetes mellitus. Medications are metformin, quinapril, and aspirin.
On physical examination, blood pressure is 95/60 mm Hg, pulse rate is 50/min, and respiration rate is 16/min. The patient is alert and conversant. The precordial cadence is not regular. There is no evidence of pulmonary or peripheral congestion, and the extremities are warm.
Laboratory studies reveal a serum troponin T level of 1.1 ng/mL (1.1 µg/L).
An electrocardiogram is shown.
Which of the following is the most appropriate next step in management of this patient's arrhythmia?
A. Cardiac catheterization
C. Permanent pacemaker implantation
D. Temporary pacing
Case 5: Small pericardial effusion
A 42-year-old man is evaluated in the emergency department for an 8-hour history of acute-onset chest pain. The patient characterizes the pain as sharp and persistent. Medical history is significant for hypertension and hyperlipidemia. Medications are lisinopril and atorvastatin.
On physical examination, temperature is 37.2 °C (99.0 °F), blood pressure is 136/84 mm Hg, and respiration rate is normal. There is no jugular venous distention. The lungs are clear to auscultation. Cardiac examination reveals no rubs, murmurs, or gallops. Peripheral pulses are full and equal.
Laboratory studies reveal an elevated C-reactive protein level and leukocyte count of 9000/µL (9.0 × 109/L). Serum troponin T level is normal on arrival and 1 hour later.
An electrocardiogram is shown. Transthoracic echocardiogram demonstrates normal left ventricular size and function without segmental wall motion abnormalities. There is a small pericardial effusion measuring 4 mm.
Which of the following is the most appropriate management?
A. Echocardiographic-guided pericardiocentesis
B. Emergent cardiac catheterization
C. Exercise treadmill stress testing
D. High-dose aspirin and colchicine
Answers and commentary
Correct answer: C. Coronary CT angiography.
Coronary CT angiography (CTA) is the most appropriate diagnostic test to perform next. This patient with an intermediate pretest probability of coronary artery disease (CAD) has chest pain without evidence of acute coronary syndrome, and he should undergo risk stratification. Because his baseline electrocardiogram (ECG) has evidence of left ventricular hypertrophy with repolarization abnormalities, which limits the ability to interpret exercise ECG findings, stress testing with adjunctive imaging or anatomic assessment for CAD is indicated. Coronary CTA is a noninvasive anatomic imaging study to evaluate for obstructive CAD. In the PROMISE trial, which compared coronary CTA with functional stress testing among patients with an intermediate pretest probability for CAD, the 2-year composite outcome (death, myocardial infarction, hospitalization for unstable angina, or major procedural complication) was similarly low with both types of diagnostic testing.
Vasodilators, such as regadenoson or adenosine, produce hyperemia and a flow disparity between myocardium supplied by unobstructed vessels and myocardium supplied by the stenotic vessel (in which the distal vasculature is already maximally dilated). In addition to identifying the presence of disease, perfusion imaging can define the location and extent of reduced perfusion and provide additional prognostic information. Single-photon emission CT with the vasodilator adenosine can be performed in patients with underlying reactive airways disease but should be avoided in patients who are actively wheezing, such as this one. The newer selective adenosine A2A receptor agonists are associated with less bronchospasm; however, bronchospasm may still occur as a result of some activation of the A2B and A3 receptors.
Coronary angiography is an invasive test that carries significant risks. It should be considered in patients who have a high pretest probability for obstructive CAD, including symptomatic patients with abnormal findings on noninvasive testing for CAD or patients with an acute coronary syndrome.
- Baseline electrocardiogram (ECG) abnormalities that limit the ability to interpret exercise ECG findings are an indication for stress testing with adjunctive imaging or anatomic assessment of coronary arteries.
Correct answer: D. Takotsubo cardiomyopathy.
Takotsubo cardiomyopathy is the most likely diagnosis. This previously healthy patient has symptoms and findings suggestive of an acute coronary syndrome. Cardiac catheterization demonstrates normal coronary arteries and wall motion abnormalities that do not follow one vascular territory, findings that are consistent with takotsubo cardiomyopathy. Takotsubo cardiomyopathy, or stress-induced cardiomyopathy, is a heart failure syndrome that typically occurs in older women and is usually precipitated by a stressful physical or emotional event, such as the death of a loved one, sudden surprise, or other acute stressors. It is associated with electrocardiographic changes suggestive of an acute myocardial infarction or a moderate increase in troponin levels, wall motion changes that extend beyond the territory of a single coronary artery, and normal or near-normal coronary arteries (<50% stenosis). Patients with a drop in ejection fraction should be treated with standard heart failure medications and typically have rapid recovery of left ventricular function.
Acute myocarditis usually presents with heart failure symptoms that develop over a few days to weeks. Occasionally, patients have symptoms for several months before heart failure is discovered. The classic presentation of viral myocarditis includes a viral prodrome with fever, myalgia, and upper respiratory tract symptoms. Patients present with dyspnea, chest pain, and arrhythmias. Electrocardiographic abnormalities are often present, along with evidence of myocardial damage with persistently elevated troponin levels. Acute-onset symptoms following an emotional event and apical ballooning on left ventriculography are not seen in acute myocarditis.
Giant cell myocarditis is an acute, rapidly progressive form of myocarditis associated with ventricular arrhythmias and progressive cardiac dysfunction despite medical therapy. This process usually occurs in persons younger than 40 years. The underlying mechanism is unknown but is thought to be autoimmune in origin. This patient's age and presentation are not compatible with giant cell myocarditis.
Tachycardia-induced cardiomyopathy is related to prolonged tachycardia or frequent premature ventricular contractions. Patients usually have findings related to the tachyarrhythmia (for example, palpitations) and heart failure. This patient's acute presentation is inconsistent with tachycardia-induced cardiomyopathy.
- Takotsubo cardiomyopathy is a syndrome of reversible ventricular systolic dysfunction that is usually precipitated by an acute emotional or physiologic stressor; the hallmark is wall motion abnormalities that extend beyond a single coronary territory, identified by echocardiography or other imaging studies.
Correct answer: D. Urgent angiography.
This patient should undergo urgent angiography. Patients with a non–ST-elevation acute coronary syndrome (NSTE-ACS) should undergo risk stratification before invasive treatment because the link between revascularization and clinical outcomes is less clear in these patients than in patients with ST-elevation myocardial infarction (STEMI). Risk stratification tools, such as the TIMI risk score, can be used to determine which patients with NSTE-ACS should be treated with an invasive strategy versus an ischemia-guided approach. An early invasive strategy benefits patients with high TIMI risk scores (5-7) and intermediate TIMI risk scores (3-4). This patient has a TIMI risk score of 5, as indicated by the presence of three traditional risk factors for coronary artery disease, aspirin use within the last week, age older than 65 years, two or more angina episodes in the past 24 hours, and significant ST-segment deviation on electrocardiogram. His score places him at high risk for death and cardiac ischemic events, and despite the absence of elevated cardiac biomarker levels, urgent coronary angiography is warranted.
Stress testing with adenosine nuclear stress testing or exercise stress electrocardiography could be considered for purposes of risk stratification if this patient declines an early invasive strategy. However, an invasive strategy has been shown to improve the composite clinical endpoint of death, recurrent myocardial infarction, and repeat hospitalization compared with an ischemia-guided approach in patients with NSTE-ACS.
In patients with suspected NSTE-ACS with a normal initial troponin level and inconclusive electrocardiographic findings, further diagnostic studies may be indicated. Coronary CT angiography is appropriate, and rest single-photon emission CT may be appropriate. However, in this patient with a high pretest probability of CAD, coronary CT angiography would only delay critical therapy.
- Patients with a non–ST-elevation acute coronary syndrome who have a high or intermediate TIMI risk score should be treated with an early invasive strategy.
Correct answer: A. Cardiac catheterization.
This patient has Mobitz type 1 second-degree atrioventricular (AV) block and evidence of an acute coronary syndrome, and she should undergo cardiac catheterization for emergent revascularization. This patient's chest pain, ST-segment elevation, and elevated troponin T level all indicate acute myocardial infarction. Additionally, the electrocardiogram demonstrates second-degree AV block, which is characterized by nonconducted P waves. The progressive prolongation of the PR interval before loss of AV conduction is consistent with Mobitz type 1 (Wenckebach block). There are many causes of AV block, including fibrosis and sclerosis of the conduction system, ischemic heart disease, and medication use (β-blockers, calcium channel blockers, digoxin). Reversible causes of AV block should always be identified and treated first. In this patient, cardiac catheterization and revascularization are indicated not only to treat the acute coronary obstruction but also to potentially correct the conduction deficit.
Transthoracic echocardiography should be performed in patients with myocardial infarction to evaluate left ventricular function and assess for potential structural complications; however, obtaining an echocardiogram is not the priority in this patient and does not help manage the arrhythmia. The most appropriate next step is cardiac catheterization.
Permanent or temporary pacemaker placement is not required in this case because the patient does not have symptomatic or hemodynamically unstable bradycardia or advanced AV block (high-degree AV block, Mobitz type 2 second-degree, or third-degree AV block). If symptomatic or advanced conduction block persists after revascularization, permanent pacemaker implantation would be recommended.
- Patients with atrioventricular block and evidence of acute coronary syndrome should undergo cardiac catheterization for diagnosis and possible revascularization.
Correct answer: D. High-dose aspirin and colchicine.
High-dose aspirin and colchicine are indicated in this patient with acute pericarditis without high-risk features. Acute pericarditis is diagnosed in this patient by the presence of sharp chest pain of acute onset without evidence of myocardial necrosis, an electrocardiogram demonstrating widespread ST-segment elevation and PR-segment depression, and a small pericardial effusion. The elevated C-reactive protein level also supports acute pericarditis. Admission to the hospital is appropriate for patients with acute pericarditis who have at least one high-risk feature, including high fever (temperature >38 °C [100.4 °F]), subacute onset (gradual onset over several days), large pericardial effusion (>20 mm), oral anticoagulation therapy, or immunosuppression. First-line therapy includes aspirin (750-1000 mg) or ibuprofen (600 mg) every 8 hours for 1 to 2 weeks plus colchicine (0.5 mg/d) for 3 months. In this patient, initiation of anti-inflammatory therapy with early outpatient follow-up is appropriate.
Pericardiocentesis is reserved for treatment of patients with tamponade or for diagnosis in patients with pericardial effusion when there is a high clinical suspicion of a malignant, bacterial, or fungal cause.
Cardiac catheterization would be appropriate in the setting of an ST-elevation myocardial infarction to facilitate percutaneous coronary intervention. However, the widespread ST-segment elevation on this patient's electrocardiogram is atypical for ST-elevation myocardial infarction, which more commonly causes ST-segment elevation within a specific vascular distribution. Furthermore, the lack of biomarker evidence of myocardial necrosis after prolonged chest pain does not support a diagnosis of acute coronary syndrome.
Although this patient has risk factors for coronary artery disease, exercise treadmill stress testing has no role. Additionally, in the setting of acute pericarditis, exercise-associated ST-T–wave changes are not interpretable for ischemic coronary artery disease.
- In patients with acute pericarditis, first-line treatment is high-dose aspirin or NSAIDs and adjuvant colchicine therapy.