The following cases and commentary, which focus on patients admitted with chest pain, are excerpted from ACP's Medical Knowledge Self-Assessment Program (MKSAP 17), which released Part A on July 31.
Case 1: Hospital without PCI
A 72-year-old woman is evaluated in the emergency department for progressive chest pain that began 2 hours ago. She has not had recent surgery or stroke. She takes amlodipine for hypertension.
On physical examination, blood pressure is 154/88 mm Hg, and pulse rate is 88/min. Cardiac and pulmonary examinations are normal.
Initial electrocardiogram shows 2-mm ST-segment elevation in leads V1 through V5 with reciprocal ST-segment depression in leads II, III, and aVF. Chest radiograph shows no cardiomegaly and no evidence of pulmonary edema.
The patient is given aspirin, clopidogrel, unfractionated heparin, and a β-blocker. Because the nearest hospital with primary percutaneous coronary intervention capabilities (PCI) is more than 120 minutes away, she is also given a bolus dose of tenecteplase.
Thirty minutes later, the patient's blood pressure has dropped to 85/58 mm Hg. Her chest pain persists, and she rates the pain as 8 out of 10. Pulmonary crackles are auscultated to the scapulae. Electrocardiogram shows 3-mm ST-segment elevation in leads V1 through V5 with reciprocal ST-segment depression in leads II, III, and aVF.
Which of the following is the most appropriate management?
A. Continued medical therapy
B. Glycoprotein IIb/IIIa inhibitor
C. Repeat tenecteplase
D. Transfer for emergency PCI
Case 2: Discharge after NSTEMI
A 58-year-old man is ready for hospital discharge following a non–ST-elevation myocardial infarction. He was treated with ticagrelor and underwent percutaneous coronary intervention with drug-eluting stent implantation. He has remained free of chest pain since admission to the hospital.
The patient's medical history is significant for hypertension and hyperlipidemia. Medications are low-dose aspirin, ticagrelor, metoprolol, lisinopril, atorvastatin, and sublingual nitroglycerin as needed.
On physical examination, blood pressure is 124/78 mm Hg and pulse rate is 54/min. BMI is 26. Lungs are clear to auscultation. Cardiac examination shows a normal S1 and S2; there is no S3, S4, murmur, or rub. The remainder of the examination is normal. His left ventricular systolic function is normal, as measured on transthoracic echocardiography on the day after hospital admission.
Which of the following is the most appropriate adjustment to his discharge medications?
A. Add diltiazem
B. Discontinue ticagrelor, start clopidogrel
C. Increase dose of metoprolol
D. Start eplerenone
E. Make no changes to his medications
Case 3: Angiography next steps
A 52-year-old man is evaluated in the hospital for progressive chest pressure over the past 3 weeks. He has a 35-pack-year history of cigarette smoking. Medical history is significant for hypertension and hyperlipidemia treated with aspirin, hydrochlorothiazide, lisinopril, and pravastatin. His brother had a myocardial infarction at age 48 years.
On physical examination, he is afebrile, blood pressure is 148/82 mm Hg, and pulse rate is 98/min. Cardiac and lung examinations are normal.
Cardiac biomarkers are elevated. Initial electrocardiogram shows 2-mm ST-segment depression in leads I, aVL, and V4 through V6.
He is admitted to the coronary care unit and given aspirin, metoprolol, nitroglycerin paste, and enoxaparin. Over the course of the first 12 hours, his chest pressure worsens, requiring intravenous nitroglycerin infusion. Subsequently, his chest pressure improves and he undergoes coronary angiography.
Coronary angiography is significant for a 70% left main coronary artery stenosis, 80% mid left anterior descending stenosis, and 90% proximal right coronary artery stenosis. Left ventricular ejection fraction is 45% with mild anterior hypokinesis. Mild mitral regurgitation is noted.
He is currently hemodynamically stable and pain free.
Which of the following is the most appropriate management?
A. Coronary artery bypass graft surgery
B. Intra-aortic balloon pump placement
C. Percutaneous coronary intervention
D. Continue current therapy
Case 4: Arrhythmia after PCI
A 75-year-old woman is evaluated in the hospital 4 hours after onset of chest pain with findings of an ST-elevation myocardial infarction. She was taken emergently to the catheterization laboratory and underwent emergency percutaneous coronary intervention for a totally occluded vessel. Her post-intervention ventriculogram demonstrated a left ventricular ejection fraction of 30%. One hour after the procedure, she developed an acute arrhythmia. Medications are aspirin, metoprolol, atorvastatin, and clopidogrel.
On physical examination, the patient is afebrile, blood pressure is 100/60 mm Hg, pulse rate is 92/min, and respiration rate is 12/min. BMI is 25. Neck examination demonstrates cannon a waves. Cardiac examination demonstrates regular rhythm with a variable S1. Lungs are clear to auscultation.
Electrocardiogram is shown.
Which of the following is the most appropriate management?
C. Implantable cardioverter-defibrillator
E. No intervention
Case 5: Aortic stenosis
A 60-year-old woman is evaluated in the hospital for a 3-week history of worsening dyspnea and chest pain. Medical history is significant for hypertension, hyperlipidemia, and previous coronary artery bypass graft surgery. Medications are aspirin, furosemide, metoprolol, and atorvastatin.
On physical examination, she is afebrile, blood pressure is 110/70 mm Hg, pulse rate is 92/min, and respiration rate is 16/min. Estimated central venous pressure is elevated. Examination at the cardiac base demonstrates a grade 3/6 late-peaking systolic murmur and a grade 1/6 diastolic murmur. An S2 is not heard.
Echocardiogram shows a markedly calcified bicuspid aortic valve with severe aortic stenosis and moderate aortic regurgitation.
Which of the following is the most appropriate treatment?
A. Aortic valve repair
B. Balloon aortic valvuloplasty
C. Surgical aortic valve replacement
D. Transcatheter aortic valve replacement
Case 6: Antiplatelet options
A 54-year-old man is evaluated in the emergency department for an episode of crushing substernal chest pain and discomfort that began 30 minutes ago. He is obese and currently smokes 1 to 2 packs of cigarettes daily. He has dyslipidemia. The patient's medications are enteric-coated low-dose aspirin and simvastatin.
On physical examination, he is afebrile, blood pressure is 146/88 mm Hg, pulse rate is 88/min and symmetric bilaterally, and respiration rate is 18/min. BMI is 32. Cardiac examination reveals a normal S1 and S2 and no S3; there is an S4. There are no murmurs or rubs. The remainder of the examination is normal.
Serum troponin levels are elevated. Hematocrit is 42% and platelet count is 220,000/µL (220 × 109/L). Electrocardiogram shows changes consistent with an inferior ST-elevation myocardial infarction. Portable chest radiograph shows a normal cardiac silhouette and no infiltrate.
The patient is treated with enteric-coated aspirin, nitrates, and a β-blocker. The hospital does not have capabilities to perform primary PCI, and the nearest primary PCI center is more than 2 hours away. The patient is administered intravenous tenecteplase.
Which of the following is the most appropriate treatment?
Answers and commentary
Correct answer: D. Transfer for emergency PCI.
This patient with ST-elevation myocardial infarction (STEMI) should be transferred to the nearest hospital with primary PCI capabilities for emergency PCI. Thrombolytic therapy failure, which occurs in up to 30% of patients, remains difficult to diagnose. Chest pain resolution, ST-segment elevation improvement, and reperfusion arrhythmias (most commonly an accelerated idioventricular rhythm) indicate successful thrombolysis. Although complete ST-segment elevation resolution is associated with coronary patency, it occurs in a minority of patients. Improvement in ST-segment elevation greater than 50% on an electrocardiogram (ECG) obtained 60 minutes after the administration of thrombolytic therapy is the most commonly used criterion to indicate successful reperfusion. Continued chest pain, lack of improvement in ST-segment elevation, hemodynamic instability, and the absence of reperfusion arrhythmias most likely indicate failure of thrombolytic therapy and indicate the need for rescue PCI. This patient has clear evidence of failed reperfusion or reocclusion (worsening of ST-segment elevation, persistence of symptoms) and now has signs of cardiogenic shock (low blood pressure, pulmonary edema). In patients with thrombolytic therapy failure, guidelines recommend immediate transfer for rescue PCI. In multiple trials of thrombolytic therapy failure, patients who underwent rescue PCI had a significant improvement in the rate of reinfarction when compared with those receiving conservative care, but no improvement in mortality.
The use of glycoprotein IIb/IIIa inhibitors has been tested in multiple scenarios in patients with STEMI. Based on these studies, their use has been limited owing to excessive bleeding events. In patients in whom thrombolytic therapy has failed, rescue PCI without the use of a glycoprotein IIb/IIIa inhibitor or additional thrombolytic agents is preferred.
A meta-analysis published in 2007 compared repeat thrombolytic therapy with conservative therapy in patients in whom initial thrombolytic therapy failed. This analysis showed no significant difference in mortality rates or reinfarction between the two groups, and outcomes in these groups were inferior to rescue PCI.
- Patients with thrombolytic therapy failure following an ST-elevation myocardial infarction should be immediately transferred for rescue percutaneous coronary intervention.
Correct answer: E. Make no changes to his medications.
No changes should be made to this patient's medications at the time of hospital discharge.
Calcium channel blockers, with the exception of nifedipine, can be used in patients with contraindications to β-blockers and in those with continued angina despite optimal doses of β-blockers and nitrates. This patient has no indications for a calcium channel blocker such as diltiazem.
There is no evidence to support a change from ticagrelor to clopidogrel after PCI for acute coronary syndrome. In the PLATO (PLATelet inhibition and patient Outcomes) trial, the use of ticagrelor was associated with a 1.9% absolute risk reduction in the occurrence of cardiovascular death, myocardial infarction, and stroke when compared with clopidogrel. A P2Y12 inhibitor (clopidogrel, prasugrel, ticagrelor) should be continued for at least 1 year for patients undergoing PCI with stent placement.
Oral β-blockers should be given to all patients with acute coronary syndrome without a contraindication (decompensated heart failure, advanced atrioventricular block, or severe reactive airways disease) and continued indefinitely. This patient is already bradycardic, and an increase in the dosage of metoprolol may be associated with symptomatic bradycardia.
In this patient with an acute coronary syndrome and preserved left ventricular function, there is no evidence to support the use of an aldosterone antagonist such as eplerenone. Based on the EPHESUS (Eplerenone Post-AMI Heart Failure Efficacy and Survival) trial, the 2007 American College of Cardiology/American Heart Association guidelines recommend the administration of an aldosterone antagonist to all patients following a non–ST-elevation myocardial infarction (NSTEMI) who are receiving an ACE inhibitor, have a left ventricular ejection fraction of 40% or below, and have either heart failure symptoms or diabetes mellitus.
ACE inhibitors inhibit postinfarction remodeling, helping to preserve ventricular function. ACE inhibitors should be continued indefinitely.
- Long-term therapy following myocardial infarction includes aspirin, a β-blocker, an ACE inhibitor, and a statin; a P2Y 12 inhibitor (clopidogrel, prasugrel, ticagrelor) should be continued for at least 1 year for patients undergoing coronary percutaneous intervention with stent placement.
Correct answer: A. Coronary artery bypass graft surgery.
This patient should undergo coronary artery bypass graft (CABG) surgery. In patients with a non–ST-elevation acute coronary syndrome (unstable angina or NSTEMI), the TIMI risk score is used to determine whether a conservative strategy or an early invasive strategy is warranted. This patient has several TIMI risk factors, including aspirin use in the past week, ST-segment deviation, elevated biomarkers, more than three traditional coronary artery disease (CAD) risk factors, and documented CAD with greater than or equal to 50% diameter stenosis; therefore, an early invasive strategy is warranted. In this patient, an oral P2Y12 inhibitor (clopidogrel, prasugrel, ticagrelor) was not administered, but if this had been given, the surgery should be delayed 5 days to allow discontinuation and excretion of the antiplatelet medication.
Intra-aortic balloon pump placement may be considered for patients with recurrent cardiac ischemia and poor left ventricular function. However, although this patient had recurrent chest pain during hospitalization, his symptoms improved with intravenous nitroglycerin and medical therapy, and he has remained hemodynamically stable. Therefore, intra-aortic balloon pump placement is not indicated.
Because this patient has multivessel disease and a reduced left ventricular ejection fraction, he should undergo CABG rather than PCI.
In patients with left main coronary artery stenosis, depressed left ventricular function, and an acute coronary syndrome, the optimal treatment strategy includes revascularization rather than medical therapy.
- Patients with multivessel coronary disease and a reduced left ventricular ejection fraction should undergo coronary artery bypass graft surgery rather than percutaneous coronary intervention.
Correct answer: E. No intervention.
This patient requires no further intervention at this time. She developed a wide complex rhythm shortly after percutaneous coronary intervention and reperfusion of her infarct-related artery. The electrocardiogram (ECG) shows a regular wide complex rhythm at 92/min with no clearly discernible atrial activity, findings consistent with accelerated idioventricular rhythm (AIVR). AIVR is postulated to result from abnormal automaticity in the subendocardial Purkinje fibers. It is observed in up to 15% of patients who undergo reperfusion of an infarct-related artery. The rate is almost always less than 120/min and usually less than 100/min. Most studies have shown that it is a benign rhythm when it occurs within 24 hours of reperfusion. This patient is tolerating the rhythm well and is already on a β-blocker for post–myocardial infarction care; therefore, no intervention is required.
Neither amiodarone nor lidocaine is indicated because AIVR is a benign ventricular arrhythmia and usually does not recur. Studies of prophylactic lidocaine after acute coronary syndromes have demonstrated potential harm, and amiodarone has been associated with decreased survival after myocardial infarction.
Cardioversion is not indicated because AIVR is a transient rhythm and, in this patient, it is well-tolerated.
AIVR usually indicates successful (or at least partial) reperfusion and is considered a reversible arrhythmia. Implantable cardioverter-defibrillator (ICD) placement is not indicated at this time given the patient's recent revascularization and nature of the arrhythmia. If the left ventricular ejection fraction remains low despite medical therapy, ICD placement might be indicated in the future.
- Accelerated idioventricular rhythm is a common complication following coronary reperfusion and does not require intervention when it occurs within 24 hours of reperfusion.
Correct answer: C. Surgical aortic valve replacement.
This patient should undergo surgical aortic valve replacement. Surgical aortic valve replacement is the only treatment of aortic stenosis associated with a survival benefit and durable symptom relief. Surgical aortic valve replacement is the treatment of choice for most patients with symptomatic severe aortic stenosis and is associated with low mortality rates for patients younger than 70 years (1%-3%).
Aortic valve repair is an option in a limited number of adult patients with aortic valve disease. In general, it is restricted to patients with aortic regurgitation and anatomically favorable aortic valve and root anatomy and can range from simple cusp plication to complex valve-sparing aortic root replacement. This patient has severe calcific aortic stenosis and a valve that is unlikely to be amenable to repair.
Balloon valvuloplasty, although important in the treatment of pediatric patients with severe aortic stenosis, has a more limited role in adults, either as a bridge to definitive treatment, to differentiate dyspnea symptoms in high-risk patients with comorbid conditions such as COPD, or to treat patients with calcific aortic stenosis with hemodynamic instability or decompensation. While balloon valvuloplasty is a potential consideration for this patient, the presence of significant aortic regurgitation is a contraindication. Improvement in aortic valve area from this procedure is modest, and many patients have residual severe aortic stenosis immediately after valvuloplasty. Balloon valvuloplasty would not be the best option for this patient.
Transcatheter aortic valve replacement (TAVR) is indicated for patients with severe symptomatic aortic stenosis who are considered unsuitable for conventional surgery because of severe comorbidities. Candidates for TAVR must be carefully selected. Surgical risk should be assessed objectively, such as by using the Society of Thoracic Surgeons adult cardiac risk score (STS score). Patients with an STS risk score of greater than or equal to 8% may be candidates for TAVR. In addition, TAVR is not approved in patients with concomitant valve disease (such as significant aortic regurgitation or mitral valve disease) and a bicuspid aortic valve. This patient has a bicuspid aortic valve and moderate aortic regurgitation; therefore, she would not be a candidate for TAVR.
- Surgical aortic valve replacement is the treatment of choice for most patients with symptomatic severe aortic stenosis and is associated with low mortality rates for patients younger than 70 years (1%-3%).
Correct answer: B. Clopidogrel.
This patient who is receiving thrombolytic therapy for a STEMI should be given clopidogrel, 300 mg orally. Clopidogrel is the most widely studied antiplatelet agent in patients undergoing reperfusion for STEMI. Clopidogrel is associated with improved outcomes and no apparent increase in the risk of bleeding when used with concomitant thrombolytic therapy and with primary PCI. In the CLARITY-TIMI 28 study examining clopidogrel as adjunctive therapy in patients undergoing thrombolysis, there was a 6.7% absolute risk reduction in the incidence of occluded infarct-related artery or recurrent myocardial infarction or death in patients assigned to clopidogrel when compared with placebo.
Abciximab is a platelet glycoprotein IIb/IIIa inhibitor that further inhibits platelet aggregation and impairs platelet activation. Glycoprotein IIb/IIIa inhibitors are used in patients undergoing PCI. Owing to the risk of increased bleeding with these agents, their use should be reserved for administration during PCI, rather than “up front” in the emergency department. Large studies have shown no clear mortality benefit and significantly higher rates of major bleeding in patients undergoing fibrinolysis treated with abciximab versus placebo. Use of platelet glycoprotein IIb/IIIa inhibitors in patients undergoing thrombolysis is not currently recommended.
For STEMI patients undergoing primary PCI, both prasugrel and ticagrelor have shown superior efficacy compared with clopidogrel. However, use of these agents in patients treated with thrombolytic therapy has not been well studied, and little evidence exists to recommend the use of either of these agents in patients receiving thrombolytic therapy.
- Patients with ST-elevation myocardial infarction undergoing thrombolysis should be given adjunctive antiplatelet therapy with clopidogrel.