Myths and Misconceptions in the Assessment and Diagnosis of Type 1 Myocardial Infarction

Approximately every 40 seconds, someone in the United States will experience acute coronary syndrome (ACS).1 Acute coronary syndrome is an umbrella term that encompasses the diagnoses of myocardial infarction (MI) and unstable angina. However, unstable angina accounts for just over 1% of hospitalizations for ACS.1 Data from the National Health and Nutrition Examination Survey from 2017 to 2020 found the overall prevalence of MI was 3.2% in US adults 20 years of age or older. Myocardial infarction prevalence rates by sex were 4.5% for males and 2.1% for females. The estimated annual incidence of MI is 605 000 new attacks and 200 000 recurrent attacks.1In 2018, a task force including members from the European Society of Cardiology, the American Heart Association, the American College of Cardiology, and the World Heart Federation developed the Fourth Universal Definition of Myocardial Infarction,2 which specified 5 subclasses of MI based on clinical and biochemical criteria (see Table 1). In all types of MI, myocardial injury is identified when there is a rise and/or fall of cardiac troponin values with at least 1 value above the 99th percentile upper reference limit.2 In the case of unstable angina, troponin elevation does not occur, but patients may experience symptoms similar to MI.Type 1 MI is colloquially called a heart attack. Most commonly, type 1 MI is caused by atherosclerotic plaque rupture or erosion, leading to acute partial or complete occlusion of 1 or more coronary arteries.2,3 Type 1 MI is often separated into 2 categories: ST-elevation myocardial infarction (STEMI) and non–ST-elevation myocardial infarction (NSTEMI). Patients with STEMI should be taken to the catheterization laboratory emergently for angiography and reperfusion; many patients with NSTEMI also require an invasive strategy including angiogram and potential coronary intervention during hospitalization,3 usually no more than 3 days after diagnosis. Although type 2 MI (injury due to supply and demand imbalance) is also common in the inpatient setting, in the present article, we discuss the assessment and diagnosis of type 1 MI only, given the need to identify and treat this MI subtype in a timely manner. The purpose of this article is to outline the role of acute care registered nurses and advanced practice nurses in the assessment and diagnosis of type 1 MI and to highlight common myths and misconceptions related to MI symptoms.Nurses in acute care settings play a critical role in the early triage and identification of individuals with type 1 MI.4 They are often the first individuals to encounter patients with a presentation consistent with this diagnosis. The initial assessment and diagnosis include the careful collection of subjective and objective information, allowing patients at highest risk to be identified and referred for emergent reperfusion therapy.There are 6 basic features of a chief concern: character, timing, duration, associated symptoms, aggravating factors, and alleviating factors. Symptoms suggestive of myocardial ischemia include chest discomfort or chest pressure that can be associated with or without radiation to the arms, upper back, or jaw; dyspnea; diaphoresis; dizziness; fatigue; nausea; vomiting; or syncope.5 The physical examination provides additional information on the patient’s hemodynamic status and aids in identifying cardiovascular instability. When a clinician examines a patient, the assessment should determine if chest pain is reproducible and evaluate for the development of signs and symptoms of heart failure, a new murmur, cardiogenic shock, and electrical instability, including ventricular tachycardia, ventricular fibrillation, or atrioventricular block.Major risk factors for type 1 MI include hypertension, hyperlipidemia, diabetes, tobacco use, obesity, and a family history of early coronary artery disease (CAD; first-degree male relative with an event before 50 years of age or first degree female relative with a first event before age 60). Other risk factors include advanced age, chronic renal insufficiency, and known atherosclerotic disease (eg, CAD or peripheral vascular disease).Troponin assays include troponin I, T, and high sensitivity. These tests are highly specific for myocardial injury and myocardial necrosis. Troponin T and I are clinically equivalent and have high sensitivity and specificity for detecting myocardial injury.6 These assays should be measured at presentation and 3 to 6 hours after presentation or symptom onset. High-sensitivity troponin is the preferred test, as it is more sensitive for early detection compared with troponin I and T.3 High-sensitivity troponin should be measured at presentation and 1 to 2 hours after symptom onset, with attention given to different cutoff values for females and males.3 Elevations in troponin can be seen in noncardiac conditions (eg, sepsis, advanced chronic kidney disease, pulmonary embolism, heart failure, hypertensive emergency, tachyarrhythmia); thus, it is important to consider troponin values in the overall context of findings from the history and physical examination.If ACS is suspected, a 12-lead electrocardiogram (ECG) should be obtained within 10 minutes of presentation or symptom onset.3 Specific ECG criteria for STEMI and NSTEMI are listed in Table 2. Briefly, STEMI is characterized by the presence of symptoms of cardiac ischemia with persistent ST-segment elevation or new left bundle-branch block. Patients with NSTEMI have cardiac-related symptoms with an elevated cardiac troponin level, with or without ECG changes (ie, T-wave inversion or ST-segment depression). However, patients with NSTEMI do not exhibit ST-segment elevation nor new left bundle-branch block. Importantly, there are several other 12-lead ECG findings that suggest critical coronary artery stenosis and/or evolving STEMI, such as de Winter T waves, hyperacute T waves, and Wellens waves.7 It has been suggested that the STEMI and NSTEMI nomenclature should be reconceptualized to be more inclusive of these other ECG findings, classifying MI instead as either occlusion MI or nonocclusion MI.7 However, this important and ongoing discussion is beyond the scope of this article.Of note, a normal or near-normal ECG decreases the risk of an MI, but NSTEMI may occur in up to 6% of these patients.8 A nondiagnostic ECG should be compared with prior ECGs. If the initial ECG is nondiagnostic of STEMI, serial ECGs should be performed when clinical suspicion of ACS is high, given the utility of electrocardiography in identifying dynamic changes consistent with ischemia and evolving MI.3In addition to 12-lead ECG and troponin findings, there are several diagnostic modalities commonly used to assist with differentiating type 1 MI from other types of myocardial injury. Chest radiographs can identify signs of fluid overload, cardiomegaly, infection, or widening mediastinum. If available, focused bedside echocardiography can identify regional wall motion abnormalities that may be a sign of ischemia; however, the sensitivity of this test is limited. Coronary computed tomography angiography (CCTA) can detect small atherosclerotic plaque and coronary dissection, however thrombus is difficult to differentiate from noncalcified atherosclerotic plaque, and plaque ruptures may be seen by CCTA; sensitivity is less accurate compared with intravascular ultrasound.9Symptoms play a critical role in helping patients recognize problems and in assisting health care professionals in identifying patients experiencing conditions like type 1 MI that require timely intervention. Unfortunately, several myths and misconceptions about MI symptoms are persistent. We focus on 4 common myths or misconceptions that patients and clinicians often hear or believe to be true related to ACS symptoms. Because a significant amount of research has explored MI symptoms more broadly, in the context of the overarching ACS, we have used the term ACS in this section.Patients and health care providers are influenced by the information they see on television, in movies, and online. Unfortunately, the portrayal of ACS in movies10 and other forms of media, such as social media,11 may be inaccurate or misleading. Shaw and colleagues10 recently reviewed 100 different movie scenes depicting ACS and found that only 10% depicted a woman experiencing ACS. They also found that the most common signs and symptoms depicted were falls and loss of consciousness, followed by chest pain, with many individuals clutching their chest.10 This portrayal of ACS as being an overwhelming, intense event has been dubbed the “Hollywood heart attack.”12 Moreover, it has been shown that the general public expects chest pain related to ACS will be overwhelming and intense when it occurs,13 similar to the portrayals often found in the media.In reality, data suggest that ACS symptom intensity varies by individual, and the overall experience can range from mild to severe.14 Rubini Gimenez and colleagues14 enrolled 2475 patients and explored characteristics of ACS-related chest pain, noting the median pain severity on a scale from 0 to 10 was about 7 for both women and men. However, about one quarter of women and men reported a pain severity of 5 or less.14 Additionally, patients have reported being surprised by ACS symptoms, expecting them to be crushing and sudden; as a result, these patients had difficulty attributing a cause to their symptoms.15 Importantly, patients who are able to attribute their symptoms to the heart are more likely to seek care quickly.16 Thus, it is important that nurses working in acute care settings recognize that ACS manifests in varying levels of severity and that patients may assume their ACS experience will be similar to what they see in the media. These misconceptions can be addressed through patient education, and nurses can also mention to patients during assessment that any level of chest discomfort could be relevant.Nurses and the general public have reported believing that there is a significant gap in women and men’s MI symptoms.4,17 However, an abundance of data over decades have demonstrated only modest sex differences in symptoms of MI; the primary symptom for both women and men is chest pain or pressure.5 In a systematic review and meta-analysis that included 27 studies, the overall pooled prevalence of chest pain was 79% for men and 74% for women.5 Women with ACS had higher odds of presenting with pain between the shoulder blades (odds ratio [OR], 2.15; 95% CI, 1.95-2.37), nausea or vomiting (OR, 1.64; 95% CI, 1.48-1.82), and shortness of breath (OR, 1.34; 95% CI, 1.21-1.48). Women had lower odds of presenting with chest pain (OR, 0.70; 95% CI, 0.63-0.78) and diaphoresis (OR, 0.84; 95% CI, 0.76-0.94). Other symptoms showed substantial overlap among men and women in prevalence. In a multisite study, 13 symptoms were recorded for patients presenting to the emergency department with symptoms suggestive of ACS.18 Women with ACS were less likely to report chest pain as their chief complaint and to report more nausea (OR, 1.56; CI, 1.00-2.42), shoulder pain (OR, 1.76; CI, 1.13-2.73), and upper back pain (OR, 2.92; CI, 1.81-4.70). In addition, women with ACS experienced more symptoms (6.1 vs 5.5, P = .03) compared with men.Evidence from the Variation in Recovery: Role of Gender on Outcomes of Young AMI [acute myocardial infarction] Patients (VIRGO) study,19 revealed that most women (87.0%) and men (89.5%) presented with chest pain (defined as pain, pressure, tightness, or discomfort). Women were more likely than men to present with 3 or more associated symptoms (61.9% vs 54.8%, P < .001). In adjusted analyses, women with an ST-segment–elevation MI were more likely than men to present without chest pain (OR, 1.51; 95% CI, 1.03-2.22). Data from the National Registry of Myocardial Infarction showed that the proportion of patients with MI who presented without chest pain was significantly higher for women than men (42.0 vs 30.7%, P < .001).20 Nonetheless, while some variations between men and women in symptom prevalence exist, sex-specific distinctions are small and represent minor differences. There do not appear to be truly unique symptoms only experienced by one sex. Together, the preponderance of data does not support the use of sex-specific chest pain descriptions for a diagnosis of ACS, nor does it support the emphasis of symptom differences in patient education or public health campaigns.In a study of 1941 patients with suspected ACS in Scotland, Ferry and colleagues21 defined typical symptom characteristics as follows: (1) typical nature of pain including descriptors of dull, heavy, tight, pressure, ache, squeezing, crushing, or gripping; (2) typical location of pain as chest (left, right, or center), arm, or jaw; and (3) typical pain described as pain of chest, arm, or jaw, with descriptors of dull, heavy, tight, pressure, ache, squeezing, crushing, or gripping. Atypical pain was classified as epigastric or back pain; pain that was burning, stabbing, indigestion-like; or any other pain description or presentation. Chest pain was reported by 92% of women and 91% of men. Of the total sample, 388 (20%) were positive for MI. Contrary to the results of other investigators, Ferry et al21 found that among people with MI, symptoms defined as typical were more common in women (77%) than in men (59%; P = .007). In contrast to the findings of Ferry et al, a recent systematic review of 74 studies of both STEMI and NSTEMI found that symptoms defined as typical (eg, chest, arm, or jaw pain) were common in both sexes, but women presented on average with more atypical symptoms such as nausea, vomiting, and shortness of breath.22 Greenslade and colleagues23 conducted a study of 358 patients with ACS in the Asia-Pacific region. The investigators categorized patients by nationality and labeled their pain as typical or atypical. Typical pain referred to chest (central, left, or right), arm, or jaw pain that was dull, heavy, tight, or crushing in character. Atypical pain was defined as epigastric pain, back pain, burning pain, stabbing pain, pain characteristic of indigestion, or other.Researchers have varied in how they define typical and atypical MI symptoms, basing the categories on symptom descriptors21–23 by sex,5 by frequency or distribution of symptoms,19 and by reference group.18 This lack of uniformity and conflicting findings makes the use of the terms typical and atypical inconsistent and ambiguous. Van Oosterhout and colleagues5 concluded that because sex differences in symptoms have been reported for years, symptoms should no longer be labeled as atypical or typical. We believe it is past time to retire the terminology of typical or atypical symptoms of MI because the terms are defined differently in different studies, studies of symptoms have occasionally been contrary, symptom description is a characteristic of the individual, and symptoms are subjective. If we stop describing symptoms as typical or atypical, it is likely that those who have been historically disadvantaged by symptom labels—such as women and minorities—will receive more timely diagnosis and treatment.24 We do support a standardized assessment of symptoms to facilitate triage, diagnosis, treatment, and research, which may lead to better patient outcomes.A chest sensation, typically referred to as chest pain, is the most common ACS symptom by a wide margin5: about 79% of men and 74% of women experience some type of chest pain during ACS. The next most common symptoms are shortness of breath and diaphoresis, experienced by just under half of women and men with ACS.5 Recent clinical practice guidelines from the American Heart Association and American College of Cardiology emphasize, however, that “chest pain means more than pain in the chest.”25(pe3) While the term pain is used, this sensation is often more accurately described as pressure, tightness, discomfort, or indigestion-like.25 Pain in ACS can also manifest as referred pain in the arms, upper back, shoulders, neck, and jaw.14,25Given the prevalence of chest symptoms, it is critical that health care professionals and patients understand the meaning of chest pain. In clinical practice, it is common for health care professionals to ask patients if they are experiencing chest pain. However, the term chest pain may mean different things to different people; for example, some may not consider sensations like pressure to be painful. In a study of 597 members of the general public from across the United States, Blakeman and colleagues13 found that about 1 in 5 participants did not associate the term chest pain with a pressure-like sensation. Additionally, patients sometimes deny having chest pain because their sensation was not painful but was, instead, a feeling of heaviness or pressure.15 Thus, it is important for nurses working in acute care settings to not only have a broad conception of chest pain in their mind but also to adjust the way they assess for chest pain to include a wider variety of chest pain descriptors. When clinicians provide education, it is also important to ensure that patients understand that chest pain can include sensations such as chest pressure, chest tightness, and chest discomfort.This article highlights the important role that acute care nurses play in the identification of type 1 MI. Careful subjective assessment, objective assessment, and diagnostic work-up facilitate timely identification of type 1 MI, thus allowing rapid treatment, reducing morbidity and mortality. Additionally, understanding the common myths and misconceptions related to ACS symptoms can help ensure nurses and nurse practitioners are assessing patients for ACS symptoms in an evidence-based way and that they are teaching patients about these symptoms using accurate information.Continued research is also needed, spanning rural, suburban, and urban areas, where patient populations, resources, and needs may differ considerably. Given delays in care-seeking by patients, it is important for researchers to develop individual and health system-level interventions to reduce patients’ ACS decision delay time and facilitate more expeditious care for ACS. Additional research is also needed to find ways for clinicians to increase speed and accuracy in identifying patients who require urgent revascularization, particularly those with NSTEMI.Continued evidence-based clinical practice and ongoing research will support improved outcomes for patients with ACS. Nurses and nurse practitioners working in acute care settings are well positioned to enact and support both of these imperatives, given the essential role that they play in the identification, diagnosis, and management of patients with ACS.