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Course # 30992 • Acute Coronary Syndrome: An Overview for Nurses

CASE STUDY 1

Patient A was admitted from the emergency department to an inpatient telemetry/stepdown unit with a diagnosis of ACS. Both the patient's initial cardiac biomarkers and initial ECGs were negative for indications of MI. However, because his initial symptoms (increased severity of chest pain, chest pain at rest) coupled with his history of PCI six months ago for an occlusion in his right coronary artery are highly suspicious for ACS, the physician admitted him for on-going observation and monitoring. A few hours after admission to the inpatient unit, Patient A experienced a chest pain attack at rest. He described the pain simply as "bad," 10/10 on the pain scale, and located in the left substernal area of his chest. His admitting medical orders included nitroglycerin, one tab sublingually every five minutes for chest pain, which may be repeated every five minutes to a maximum of three doses as needed. The nurse obtained an ECG and notified the physician.

After a single nitroglycerin tablet, Patient A reported that his chest pain dropped to 4 on a scale of 10, and his blood pressure remained slightly elevated.

Per physician orders, an ECG should be obtained if Patient A has chest pain. Ideally, the ECG would be taken while the patient is still having chest pain. Clinically significant signs of myocardial ischemia, such as ST depression and T-wave inversion, may be seen on 12-lead ECG during chest pain episodes.

After administration of two sublingual nitroglycerin tablets, Patient A's chest pain was relieved. He reported that he was chest pain free. One hour later, he again developed chest pain and required a third sublingual nitroglycerin tablet for relief. His blood pressure was elevated during this attack; when his pain was relieved, his blood pressure returned to his baseline normal. Less than one hour later, Patient A developed a third bout of chest pain. He rated the pain as 10/10, and his blood pressure increased to 190/120 mm Hg. Three sublingual nitroglycerin tablets again reduced his chest pain to 0 and his blood pressure decreased to baseline. Because the chest pain episodes are increasing in frequency and intensity, the physician decided to initiate a continuous nitroglycerin drip.

Patient A continued to experience severe chest pain; initiation and titration of the nitroglycerin infusion to higher doses did not relieve his pain. ECG showed ST depression in the inferior leads, and his most recent cardiac biomarkers indicated that his troponin levels were positive for myocardial damage. The physician was notified and ordered morphine 2 mg. Patient A remained hypertensive, and his chest pain persisted at a lower intensity (5/10). The physician ordered 5 mg IV of metoprolol to be administered immediately and 25 mg metoprolol to be taken by mouth twice a day.

Patient D was scheduled to go to the cardiac catheterization laboratory for a left heart catheterization and probable PCI with stent to treat an obstruction in the circumflex branch of his left coronary artery. The cardiac catheterization laboratory physician's orders specified that Patient D should receive a loading dose of 300 mg of clopidogrel on call to the catheterization laboratory. When the nurse brought the patient the medication as ordered, he commented, "I know that one. They wanted me to take it last year after my last heart attack and stent. But I couldn't afford it. That stuff is expensive!"

CASE STUDY 2

Patient K, a man 59 years of age, was admitted to the hospital with a diagnosis of possible H1N1 flu. He was treated with appropriate medical therapy, and his condition improved. On the day before his expected discharge, he called the nurse and complained of a severe, stabbing pain in his chest. He was diaphoretic and complained of feeling nauseated. His blood pressure was elevated to 170/90 mm Hg, and his heart rate was 100-110 beats per minute. He rated his pain 10 out of 10 and stated the pain was located in his left chest, left arm, and back. An ECG was completed, and blood for cardiac biomarkers was obtained. The 12-lead ECG showed non-specific ST-wave changes. A serial 12-lead ECG taken 30 minutes later, however, showed ST elevation in the anterior leads. Cardiology confirmed a diagnosis of STEMI.

Upon further questioning, Patient K reported a history of CHD with stent placement 5 years previously and CABG surgery 10 years previously. The medical team determined that primary PCI was indicated to open the occluded, infarct-related vessel. While awaiting the start of the procedure, Patient K received aspirin 325 mg and 600 mg of clopidogrel. He also received a bolus of abciximab, and a continuous infusion was started.

Patient K underwent successful PCI to a branch of his circumflex artery, with placement of a drug-eluting stent. Following the procedure, he was transferred to the coronary care unit for observation and monitoring. He was placed on continuous ECG monitoring, which assessed ST-segment changes in the most appropriate leads. Vital signs were checked frequently, and the right femoral site and right pedal pulse were assessed for bleeding, signs of hematoma, or disrupted circulation. The patient remained on bed rest per orders. Laboratory tests were sent at prescribed intervals to monitor cardiac biomarkers and complete blood count. Patient K was also monitored for signs of recurrent ischemia, including recurrent chest pain and recurrent or new ST-wave changes.

Patient K recovered from the PCI. During the postprocedure period, it was noted that his groin site was dry, with no evidence of bleeding or hematoma. His pedal pulse remained strong and readily palpable. His vital signs were stable. The blood pressure measurement remained around 130 mm Hg systolic, and the patient remained chest pain free. ECG showed no further ischemic changes. His initial post-PCI complete blood count showed a slight drop in platelet count, and the initial post-PCI biomarkers showed his elevated levels starting to trend down. The follow-up laboratory results eight hours later showed his platelet count unchanged and his biomarkers continuing to trend downward. Patient K was discharged uneventfully 24 hours later.

CASE STUDY 3

Patient E is a man, 54 years of age, who presented to his primary care physician's office with complaints of chest pain. Upon arrival at the primary care physician's office, he was chest pain free. A 12-lead ECG was performed and showed no changes from previous ECGs. The patient's vital signs were found to be stable and within his normal range: blood pressure 135/78 mm Hg, heart rate 68 beats per minute and regular, and respirations 16 breaths per minute and unlabored. He was afebrile.

Comments and Rationale : Persons who present in any healthcare setting with a complaint of chest pain should be evaluated for the presence of signs and symptoms of ACS. Appropriate assessment measures include vital signs and a 12-lead ECG to assess for changes suspicious for ischemia or infarct. Patient E was chest pain free on arrival, his ECG did not show any acute ischemic changes, and his vital signs were stable. Further assessment by the healthcare provider is indicated.

The physician questioned Patient E about his chest pain episodes. The patient reported that, until about a week ago, he just had been having his "usual" occasional chest pain when he "worked too long, too hard in the yard." However, over the last week, his chest pain attacks had been lasting longer and requiring more sublingual nitroglycerin tablets for relief. The previous night he had experienced a prolonged episode of chest pain at rest and decided to seek medical attention.

Comments and Rationale : Chest pain that occurs in a predictable pattern, is generally triggered by the same level of exertion, and is readily relieved by rest and sublingual nitroglycerin can be classified as "stable angina." Stable angina is a hallmark symptom of CHD but is rarely indicative of acute myocardial ischemia. However, chest pain attacks that increase in frequency, severity, and/or require additional nitroglycerin tablets to achieve relief and severe chest pain that occurs at rest are indications that the patient's angina has become "unstable." Immediate medication evaluation and intervention is indicated.

The physician reviewed Patient E's medical record and noted that he had a history of CABG surgery five years previously. Two years ago, Patient E required placement of a drug-eluting stent to open a blockage in one of the saphenous vein grafts from his prior CABG surgery. Patient E was also prescribed medication for dyslipidemia; his most recent laboratory tests showed his LDL was borderline high at 135 mg/dL. He stopped smoking following the stent placement two years previously. The patient was approximately 30 pounds overweight. When the physician mentioned his need for weight loss, the patient's usual reply was, "It's either the weight or the smoking. I can't manage both."

Comments and Rationale:A careful history and physical can provide information necessary to triage patients who present with chest pain and stratify their risk for serious consequences such as acute MI. Major risk factors for ACS include a known history of CHD, history of occlusions that have required intervention to restore blood flow and oxygen supply, and the presence of modifiable risk factors such as obesity, dyslipidemia, smoking, and hypertension.

Given the patient's known CHD, previous history of CABG and PCI with stents, and his continuing risk factors, the physician instructed Patient E to go to the emergency department of the local hospital. The patient declined transport by emergency medical services and insisted on driving himself to the hospital.

Comments and Rationale : ACCF/AHA guidelines strongly recommend that persons with possible ACS be transported to the hospital by emergency medical services. Transport by emergency medical services provides the opportunity for skilled healthcare providers to assess the patient, obtain an immediate ECG, and administer aspirin and other therapies as indicated. In addition, emergency medical services can notify the receiving emergency department to expect the patient so immediate triage and evaluation are facilitated. ACCF/AHA guidelines strongly discourage persons with possible ACS from driving themselves or asking friends or family members for transport to the emergency department.

In the emergency department, Patient E developed an episode of chest pain. He rated the pain as 10 out of 10 and located the pain on the left side of his chest, substernal region. He was slightly diaphoretic with a blood pressure of 170/90 mm Hg and a heart rate of 110 beats per minute.

Comments and Rationale : Severe, intense chest pain located in the left substernal area of the chest coupled with diaphoresis and vital sign changes is a strong indicator of ACS.

The emergency physician activated the chest pain protocol. Patient E received 325 mg of aspirin with instructions to chew it before swallowing. He was also given sublingual nitroglycerin, and supplemental oxygen at 2 liters per nasal cannula was started. A 12-lead ECG was performed, and blood work, including troponin T level, were drawn.

Comments and Rationale : In ACS, aspirin is given immediately for its antiplatelet action to decrease the risk of thrombus formation. Sublingual nitroglycerin acts a vasodilator, reducing myocardial workload while increasing myocardial oxygen supply. It also helps to lower elevated blood pressure.

The 12-lead ECG showed non-specific ST-segment and T-wave changes. Five minutes after one sublingual nitroglycerin tablet, the patient reported that his chest pain was 10/10; his blood pressure was 140/88 mm Hg. A second sublingual nitroglycerin tablet was given; five minutes later, Patient E reported his pain was 8/10, and his blood pressure remained at about 140/88 mm Hg. A third sublingual nitroglycerin tablet was administered, and minutes later, the patient reported that his pain was 5/10. His blood pressure was measured as 132/80 mm Hg. The physician ordered 2 mg of morphine IV.

Comments and Rationale : In patients with clinical symptoms of ACS, nonspecific ST-segment and T-wave changes are worrisome. Serial ECGs may be indicated to identify the presence of an evolving MI. Sublingual nitroglycerin may be given every five minutes up to three doses if the patient does not become hypotensive. The goal of analgesic therapy in ACS is to get the patient "chest pain free." Morphine may be used to treat chest pain that does not resolve after three sublingual nitroglycerin tablets. Morphine acts as a vasodilator, decreasing myocardial oxygen demands and increasing myocardial oxygen supply.

After receiving morphine, Patient E reported that he was chest pain free. His blood pressure and heart rate returned to the "usual" level. His initial troponins were returned negative for cardiac damage. The physician made the decision to admit the patient to the telemetry/stepdown floor for further observation and monitoring. His admitting diagnosis was UA/possible ACS, and his admitting orders included orders for serial troponin monitoring, continuous ECG monitoring, and immediate 12-lead ECG with chest pain.

Comments and Rationale : The combination of Patient E's increasingly severe and frequent chest pain episodes coupled with the presence of nonspecific changes on 12-lead ECG and his previous history of CHD, CABG, and stent placements are indicators that the patient is at increased risk for MI. Serial troponins can provide important diagnostic information and may be used to confirm or rule out a diagnosis of NSTEMI. Continuous ECG monitoring provides information about ST-segment changes indicative of ischemia and infarct. A 12-lead ECG recorded during chest pain can also provide information about possible ischemia/infarction and what part of the heart is at risk.

Patient E's second set of cardiac biomarkers returned showing elevated troponin levels. A repeat ECG indicated no evidence of ischemia or infarct. A third set of cardiac biomarkers approximately eight hours later showed that troponin T was positive for myocardial damage. A diagnosis of NSTEMI was confirmed. Another ECG taken immediately after the return of the laboratory work did not show any evidence of ischemia; however, minutes later, Patient E developed chest pain. ST-segment depression in the inferior leads was noted on continuous ECG monitoring.

Comments and Rationale : ECG changes and cardiac biomarker elevation indicative of myocardial ischemia and infarction can develop over a period of minutes to hours. In persons who have persistent chest pain with initial negative ECG findings and cardiac biomarker levels, serial measurements are indicated. As was the case with Patient E, biomarker changes indicative of infarct may develop several hours after the initial episode of chest pain. Presence of elevated cardiac troponin levels, in the absence of ST-segment elevation, is diagnostic for NSTEMI.

The physician ordered a continuous heparin infusion along with a bolus dose of eptifibatide followed by a continuous infusion. Patient E had been administered aspirin in the emergency department; on the floor, he received 600 mg of clopidogrel along with a low dose of a beta blocker. Patient E developed another episode of chest pain that was not relieved by sublingual nitroglycerin or IV morphine. As a result, the physician ordered a continuous nitroglycerin drip.

Comments and Rationale : The immediate goal of treatment in NSTEMI is to relieve ischemia and prevent ongoing infarction. Key elements of management include aspirin (chewed) and clopidogrel to reduce platelet formation and aggregation, and nitroglycerin and morphine for relief of ischemic pain through reduction of myocardial workload and decrease in myocardial oxygen demand. Chest pain unrelieved by sublingual nitroglycerin may be treated with a continuous nitroglycerin infusion titrated to relieve chest pain and maintain a blood pressure within a prescribed range. A third major element in the management of acute NSTEMI is anticoagulation. A continuous heparin infusion is one option for anticoagulation; use of heparin may be combined with the use of a glycoprotein IIb/IIIa inhibitor. In acute stages of NSTEMI, a glycoprotein IIb/IIIa inhibitor such as eptifibatide may be used. Eptifibatide may be initiated prior to cardiac catheterization, and the infusion can be maintained for a specified period of time following catheterization and stent placement.

Patient E was taken to the cardiac catheterization laboratory for diagnostic coronary angiography and possible PCI. Cardiac catheterization revealed that he had an area of blockage in his right coronary artery. The patient's previous stent remained open, and the other vein grafts from previous surgery were also patent. A PCI with placement of a bare-metal stent was performed.

Comments and Rationale : Intracoronary stents are deployed during PCI to help to keep the lumen of the affected vessel open. The choice of type of stent (bare-metal or drug-eluting) is left to the interventional cardiologist performing the procedure.

Following recovery in the cardiac catheterization area, Patient E was returned to his room. The postcatheterization orders included instructions for bed rest for 4 hours, continuation of the eptifibatide drip for a total of 18 hours following the conclusion of the PCI procedure, and serial monitoring of cardiac biomarkers and complete blood count. Nursing care included continuous ECG monitoring, frequent vital sign checks, frequent monitoring of the arterial puncture site for evidence of bleeding or hematoma, and assessment for signs of recurrent chest pain (indicative of reocclusion of the infarct-related vessel) or severe left flank pain (indicative of retroperitoneal bleed). Patient E was encouraged to drink fluids, and his urine output was monitored and recorded.

Comments and Rationale : Key elements of care during the immediate post-PCI period include monitoring for bleeding, maintaining the eptifibatide drip as ordered to decrease the risk of stent occlusion, and monitoring the patient for changes in vital signs, heart rhythm, or the development of chest pain. Potential complications during this period include bleeding from the puncture site and reocclusion in the coronary artery.

Patient E's initial blood work following the PCI showed a drop in his platelet count from the high normal to borderline low range. A second set of blood work sent six hours later showed a dramatic and significant drop in his platelet count. The physician was notified and ordered the discontinuation of the eptifibatide infusion. Appropriate nursing interventions included close monitoring of the patient for any signs of bleeding.

Comments and Rationale : Use of glycoprotein IIb/IIIa inhibitors can cause an unsafe drop in platelet counts in some individuals. Careful monitoring of platelet levels at specified intervals during the infusion is indicated to identify this complication promptly and intervene in timely fashion.

CASE STUDY 4

Patient Z, a woman 63 years of age, presented to the emergency department with a complaint of intermittent epigastric and chest discomfort. She reported that the discomfort had occurred intermittently over the previous two to three weeks. When questioned, she admitted that she had felt more fatigued and had periods of shortness of breath and light-headedness over the same time period.

Comments and Rationale : While women may present with ACS symptoms similar to men, they may also present with symptoms labeled as "atypical." Epigastric pain, fatigue, and light-headedness have been identified as "atypical" symptoms associated with ACS.

At the time of presentation to the emergency department, Patient Z reported that she was experiencing no discomfort. Her blood pressure was elevated at 210/120 mm Hg, her heart rate was 84 beats per minute, her respirations were even and easy, and she did not appear to be in acute distress. An initial ECG showed no signs of acute ischemia or infarct but did reveal a pathologic Q wave. The initial cardiac troponin I returned indicating the level to be "borderline" but not yet elevated. When asked, Patient Z admitted that she has had high blood pressure "for a while" and that she does not always take her medications as prescribed.

Comments and Rationale : At the time of admission to the emergency department, Patient Z shows no signs of acute ischemia or infarct; she is chest pain free, her ECG shows no ST-segment elevation or ST-segment depression, and her initial cardiac troponin level is equivocal. However, she has at least one major risk factor for CHD and subsequent ACS: hypertension that appears poorly controlled. Her ECG also shows evidence (i.e., a pathologic Q wave with no evidence of ST-segment elevation or T-wave inversion) that she had experienced an MI sometime in the past.

The emergency department physician admitted Patient Z to the telemetry unit with hypertension and possible ACS/UA. Serial cardiac biomarkers remained essentially unchanged from the initial levels. Repeat 12-lead ECG eight hours after admission showed no indications of acute ischemia or infarct. Patient Z had several episodes of epigastric discomfort/chest discomfort following her transfer to the telemetry unit. She developed nausea and emesis with one episode. Sublingual nitroglycerin was effective in relieving her discomfort. Oral medications to lower her blood pressure were effective and subsequent measurements indicated a blood pressure of 150/88 mm Hg. When asked, the patient denied any history of a previous MI. When asked if a physician had ever instructed her to take a lipid-lowering medication, she replied that she "couldn't afford it."

Comments and Rationale : Risk stratification indicates that Patient Z has risk factors for CHD and ACS but is not currently experiencing an acute episode. An early conservative approach, including a stress test, is indicated.

The physician ordered a fasting lipid panel, to evaluate for dyslipidemia, and an exercise stress test.

Comments and Rationale : The focus of medical therapy for Patient Z will be on continued risk stratification and risk factor reduction. Exercise stress testing will provide information about presence of ischemic disease and risk for adverse cardiac events.

During the exercise stress test, Patient Z developed chest pain, diaphoresis, and nausea before reaching the targeted heart rate. She underwent a follow-up cardiac catheterization with placement of a stent in her right coronary artery. Following a conversation with the patient regarding adherence to dual antiplatelet therapy, the interventional cardiologist chose to implant a bare-metal stent.

Comments and Rationale : Inability to reach a heart rate target due to development of chest pain or other ischemia-associated symptoms during a stress test is an indication of ischemic disease and high risk for future ischemia and infarct. Cardiac catheterization is indicated; it provides direct visualization of coronary circulation and permits percutaneous intervention if indicated. Implantation of drug-eluting stents should generally be avoided in persons for whom adherence to dual antiplatelet therapy is unlikely.

Patient Z recovered uneventfully from the PCI. Her prescribed medications included simvastatin, metoprolol, hydrochlorothiazide, additional oral antihypertensive medications, her "usual" oral hypoglycemic medications, aspirin, and clopidogrel. Patient Z's fasting lipid panel showed a LDL of 190 mg/dL and a total cholesterol of 250 mg/dL. The discharge nurse began planning for Patient Z's return home.

Comments and Rationale : Unless complications develop, patients only remain in the hospital 24 to 48 hours after PCI. Therefore, assessment of discharge needs and initial teaching should begin immediately.

The nurses caring for Patient Z noted that she was taking several medications that were new to her: simvastatin, metoprolol, aspirin, and clopidogrel. From the admission assessment, the nurse saw that the patient stopped taking her previously prescribed statin because of its cost. She also noted that Patient Z's fasting lipid levels were high; some diet teaching might be helpful in assisting the patient to modify her diet and reduce this risk factor. The nurse referred Patient Z to social work for possible financial assistance with medications and to the dietician for assistance with diet changes. When questioned, the patient stated that she preferred written information in English, so written material on reducing cholesterol and triglyceride consumption were provided as well as a list of local resources. The nurse also reviewed all of Patient Z's current medications with her when she administered them, stressing the importance of taking them as prescribed and making sure that the patient understood the purpose and prescribed dosage of all her new medications. Provided education and the patient's responses were recorded in the patient's medical record.

Comments and Rationale : Patient education should be provided in the language and format that the patient prefers. Teaching about new medications and facilitating the patient's ability to obtain medications after discharge through referral to social work or appropriate resources is very important. Short hospital stays do not permit time for exhaustive, extensive education. Written materials and referrals that the patient can use to follow up on recommended lifestyle changes are therefore helpful. Risk reduction for Patient Z will involve major lifestyle changes. Healthcare practitioners in all settings who encounter this patient will have a role to play in promoting increased adherence to recommended measures.

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