The NSTEMI Curbside Consultation
Disclosure of Relevant Financial Relationships: As a provider accredited by the Accreditation Council for Continuing Medical Education (ACCME), the University of California, Davis, Health must ensure balance, independence and objectivity in all its CME activities to promote improvements in health care and not proprietary interests of a commercial interest. Authors, reviewers and others in a position to control the content of this activity are required to disclose relevant financial relationships with commercial interests related to the subject matter of this educational activity. The Accreditation Council for Continuing Medical Education (ACCME) defines a commercial interest as “any entity producing, marketing, re-selling, or distributing health care goods or services consumed by, or used on patients” and relevant financial relationships as “financial relationships in any amount occurring within the past 12 months that create a conflict of interest.
Drs. Patrick Romano, Debra Bakerjian, Amparo Villablanca, Gordon X. Wong, Ulfat Shaikh, and Saivageethi Nuthikattu (author(s) and reviewers) for this Spotlight Case and Commentary have disclosed no relevant financial relationships with commercial interests related to this CME activity.
- Describe key causes of diagnostic errors including cognitive bias, anchoring bias, and confirmation bias and discuss strategies to mitigate these biases
- Increase understanding of differences in cardiovascular disease presentations between men and women
- Discuss the appropriate use of and best practices for curbside consultations in acute care settings
- Articulate advantages and pitfalls of curbside consultations
A 52-year-old woman with coronary artery disease (CAD) and a history of ST-segment-elevation myocardial infarction (STEMI) and drug-eluting stent placement in the left anterior descending artery (LAD) in 2013, complicated by ischemic cardiomyopathy, presented to the Emergency Department with dyspnea, cough and fever. She was found to have hypoxemia and her chest X-ray showed patchy consolidations bilaterally, confluent in the right upper lung. She had a positive troponin test without ischemic electrocardiographic changes. She was admitted and started on antibiotics for community-acquired pneumonia. Given her history of progressive dyspnea, a transthoracic echocardiogram was performed that showed her left ventricular systolic function had worsened from an ejection fraction (EF) of 50-55% to 25-30%, without new wall motion abnormalities. Her troponin continued to rise, from 0.09 to 0.15, without electrocardiographic (ECG) changes. The inpatient medicine team obtained a “curbside” cardiology consultation; the consultant felt that her condition was consistent with demand ischemia and that the worsening of her systolic function could be consistent with acute pulmonary edema. The patient was therefore diuresed and continued on antibiotics. Her hypoxemia improved with resolved infiltrates on chest radiography. She was discharged home after a four-day hospitalization to complete her antibiotic course; she was told to resume her home diuretic regimen and plan for cardiology follow-up within a week.
The patient’s follow-up with cardiology did not occur until two months after discharge. At that time, a nuclear stress test was ordered, which showed a large perfusion defect suggestive of infarction. Subsequent left heart catheterization with coronary angiography showed 100% mid-LAD occlusion and a hypokinetic scar in the distal anterior wall and apex. Cardiac magnetic resonance imaging (MRI) showed no viability of the mid-anterior wall of the left ventricle. A multidisciplinary conference with interventional cardiology and cardiothoracic surgery specialists concluded that there was no benefit to be gained by percutaneous or surgical coronary revascularization.
By Amparo C. Villablanca, MD, and Gordon X. Wong, MD, MBA
Two major issues contributed to a poor outcome for this 52-year-old woman with a known history of coronary artery disease and ischemic cardiomyopathy, who was admitted to the hospital for presumed community-acquired pneumonia. First, clinicians made a series of diagnostic errors, failing to recognize an acute coronary syndrome (ACS) in a female patient who was at high risk. Second, curbside consultation was used inappropriately, leading to incorrect recommendations and lack of timely follow-up. Critical analyses of both issues can help to identify and bridge existing gaps in, and lead to improved processes that should reduce the likelihood of similar adverse outcomes occurring in the future.
In this era of patient-centered care and outcomes, it is important to recognize that diagnostic errors remain a prevalent ‘blind spot’ in patient safety and contribute to poor patient outcomes. Studies such as the Harvard Medical Practice Study1 point out that in hospitalized patients, 17% of preventable errors are diagnostic errors, and autopsy studies reveal that 9% of patients experience undetected diagnostic errors before death. The cumulative effect of these errors can lead to severely harmful, if not fatal, outcomes in millions of people in the U.S. yearly.2 Diagnostic errors are often rooted in cognitive biases within a clinician’s thought processes, leading to incorrect diagnoses.3 These biases include relying too heavily on past case experience (“availability bias”), relying on one’s initial diagnostic impression despite emerging information to the contrary (“anchoring bias” or “premature closure”), incorrect use of cues and collateral information that is actually irrelevant (“framing bias”), and placing undue reliance on test results or expert opinion (a phenomenon known as “blind obedience”).
Several strategies have been proposed to prevent diagnostic errors. These strategies include mitigating the effects of subtle cognitive biases, addressing cognitive errors by providing physicians with objective information to assist with medical decision-making, and improving physician knowledge and experience.3 In the context of the case at hand, several domains of knowledge are relevant.
Prevalence of Cardiovascular Disease among Women
In the United States, cardiovascular disease (CVD) kills more women yearly than men (e.g., 299,578 female deaths in 2017), accounting for 1 in every 5 female deaths, and as such is the leading health issue for women.4 The pathophysiology and morbidity of ischemic heart disease differ substantially between women and men for several reasons, including gender-related differences in the anatomy, physiology, and pathogenesis of coronary disease.5 Cardiovascular disease among women, compared with men, is under-prevented, under-diagnosed, under-treated, and under-studied, all of which contribute to gaps in knowledge, underuse of proven therapies (diagnostic, medical and interventional), and cardiovascular gender disparities. Consequently, women experience higher mortality and poorer outcomes from cardiovascular disease than men.6 An additional factor driving worse outcomes among women is gender-related bias that may stem from underestimating risk,6-9 limited patient and health professional awareness of gender differences in the manifestations of cardiovascular disease, and the discomfort health professionals can experience in managing women with heart disease.10
Use of Pre-test Probability to Help Guide Clinical Decision-Making
One of the factors contributing to gender-related disparities in CVD is that women are less likely to be identified as high-risk. Originally designed to predict CVD events, the Framingham Risk Score may inaccurately predict risk of CVD in women affected earlier in life by stroke, angina, and heart failure.11 The Framingham Heart Study also showed that MI is the first manifestation of CVD in 51% of men and 44% of women,12 although the patient in this case presented with STEMI. Regarding obstructive CAD, women have worse prognoses than men, higher short- and long-term mortality rates, and substantially higher risk of subsequent MI, heart failure, and death.13 Furthermore, women also have increased risk of complications during hospitalizations for ACS, including re-infarction, death, heart failure, and stroke.14 Based on this phenotype for women, lack of recognition of the high probability of a cardiac event in this case may have contributed to a worse patient outcome. The patient’s prior history of CAD and STEMI with stent placement to the LAD greatly increased the pretest probability of ACS, yet the importance of this historical information was not recognized. The significant drop in EF could also not be fully explained by myocardial depression from CAP-related sepsis alone.
Over-reliance on the Presence of Chest Pain and ECG Changes for the Diagnosis of MI
Chest pain, elevated cardiac enzymes, and an abnormal ECG are the typical triad used to diagnose acute myocardial infarction (MI). However, as patients with non-STEMIs (NSTEMIs) are more frequently presenting with minimal symptoms or ECG findings, more reliance has been placed on biomarkers of myocardial ischemia for making diagnoses. Cardiac troponin (cTn) T and I are expressed by the myocardium and are the preferred biomarkers to use for measuring myocardial injury. While troponin elevation is specific for myocardial injury, not every troponin elevation indicates an MI. Elevated troponin with minimal ECG findings can occur with several conditions in the absence of coronary artery disease, such as heart failure, renal failure, sepsis, arrhythmia, and pulmonary embolus, among others.15 Thus, clinical presentation and other diagnostic studies can help to rule in or rule out alternative diagnoses. In the patient in this case, community acquired pneumonia (CAP), evidenced by the patient’s dyspnea and radiographic findings, could have caused cTn elevations, and high cTn levels are known to predict mortality in CAP.16 Therefore, attributing the elevated cTn and dyspnea to CAP was partly correct, but ‘atypical’ symptoms such as dyspnea also suggest myocardial ischemia and MI, especially in women, who have a higher incidence of silent MI17 and more often present with symptoms other than angina.18 In fact, younger women are more prone to plaque erosion than plaque rupture, which may contribute to more atypical MI presentations than are seen among men.19 Failure to recognize sex variation in the presenting symptoms for acute coronary syndromes may contribute to delayed referrals and delayed or missed diagnosis.
According to American College of Cardiology (ACC) guidelines, the combination of clinical history and elevated cTn in this case should have led to consideration of coronary angiography or other cardiac imaging modalities.20 While the relatively low cTn levels with small interval changes may have provided a false sense of reassurance, small changes in cTn levels are common among patients with MI,21 and additional monitoring of cTn might have led to the recognition of a “rise and fall” pattern and concern about an acute ischemic presentation. In this patient’s case, clinical decision-making may have been further compromised by anchoring bias (i.e., prematurely closing on a fixed diagnosis of CAP) and confirmation bias (i.e., misinterpreting the absence of chest pain and ECG findings as confirmation of CAP). If so, both of these decision-making biases could have been the result of insufficient knowledge of gender differences in the presentation, prevalence, and severity of coronary artery disease.
This term is frequently used to describe patients with a myocardial oxygen supply-demand mismatch, but without known CAD, who often have elevated levels of cardiac biomarkers like cTn. Although demand ischemia, in this case, was attributed to CAP or heart failure, it should be recognized that acute heart failure can also result from acute myocardial ischemia. Multiple mechanisms are now known to cause or contribute to the current classification of five subtypes of MI.20 The 4th Universal Definition of Myocardial Infarction22 states that “demand ischemia” represents type 2 MI, defined as “MI caused by a mismatch between oxygen supply and demand by a pathophysiological mechanism other than coronary atherothrombosis (i.e., type 1 MI).” In addition, at least one of the following criteria is needed to diagnose type 2 MI: a) symptoms of acute myocardial ischemia, b) new ischemic ECG changes or development of pathologic Q waves, and c) imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a pattern consistent with an ischemic etiology. In a patient like the one in this case, with known CAD, rising cardiac biomarkers, and a new drop in EF concerning for a primary ischemic event, it is imperative to consider acute atherothrombosis. In addition, type 2 MI and myocardial injury are both related to poor outcomes, and ischemia thresholds vary substantially by the magnitude of the stressor and the extent of underlying cardiac disease,22 so testing to assess the severity of CAD is warranted.
In summary, this case exemplifies many of the following known major disparities in CVD between men and women:
- Women are less likely to be identified as high-risk, and thus preventive interventions (e.g., cholesterol-lowering medications) are less likely to be prescribed.23
- Women are referred for cardiovascular diagnostic tests less often than men,24 perhaps due to more atypical presentations and underestimation of the pre-test probability of CVD.
- Women are more likely to have adverse outcomes, even after CVD is recognized and treatment is initiated.26
- Although there have been significant reductions in coronary heart disease mortality over time, over the past 15 years reductions in coronary heart mortality in women younger than 55 years of age has slowed compared to men in the same age group.27
Heightened awareness of CVD as the leading killer of women and better understanding of gender differences in the presentation and pathophysiology of CVD will facilitate better identification and treatment of all women at risk. Clinical management should be guided by published, evidence-based guidelines for women including the American Heart Association and ACC guidelines for ACS/MI and their gender-specific subsections.14, 28-31 However, it is not sufficient to focus entirely on diagnostic error in this case, as curbside consultation played a significant role in the outcome.
Use of Curbside Consults
Physician consultations are common in both inpatient and outpatient settings, where a treating physician requests the advisory opinion of a colleague in preparing to provide treatment for a patient.32 A formal consultation involves a physician who examines the patient, performs comprehensive medical record review, and provides written recommendations.33 In comparison, informal consultations (referred to as curbside consults) involve a more limited role of the consultant, who answers direct questions posed by the treating physician but generally does not see the patient or review the medical record.33,34 Recent improvements in electronic medical record systems and increasing use of telehealth services have led to implementation of electronic consultations (e-consults), whereby specialists provide documented clinical recommendations following review of electronic records, without an in-person visit.35
Curbside consults are a valuable part of medical practice. A survey of 700 generalist and specialist physicians from Massachusetts reported high approval of curbside consultations.36 Factors such as time constraints, insurance coverage, geographic location, or patient preference can often make formal consultations difficult to obtain.34 Curbside consults serve as a useful alternative by improving access to specialist knowledge, providing more timely coordination of patient care, and promoting healthcare efficiency.37 The “bidirectional” communication between physicians facilitates effective patient triage, identification of early testing needs, and involvement of the right subspecialist.38 Many specialists have expressed that curbside consultations increase professional satisfaction by providing opportunities to educate and maintain good relationships with colleagues.36,39 Despite these benefits, many concerns have been raised regarding curbside consultations.
Physicians have reported that clinically important information is often inadequately conveyed during curbside consultations, and studies have found that incomplete and inaccurate information is relayed in about half of all cases.39,40 Exchanging incomplete information may cause the expert consultant to recommend expensive tests with unnecessary risks or to provide generalized recommendations that may convey a false sense of reassurance.41 In such circumstances, patients may be harmed and physicians may incur increased medicolegal risk, particularly the treating physician with a legally established patient-physician relationship.34 While formal cardiology consultations for preoperative risk stratification or heart failure assessment are well-described in the literature, curbside consultations involving cardiologists are not well-studied. A 1998 study reported that cardiologists are among the top three medical subspecialists receiving the most frequent curbside consultation requests from primary care physicians.39 In addition, pilot results from a study on a cardiac “curbside” initiative at Massachusetts General Hospital in 2014 found that curbside consults comprised one-tenth of all cardiology referrals and did not affect the volume of cardiology consultations.42 Finally, economic outcomes from a Minneapolis-based telephone cardiology curbside consult service showed an annual savings of $3.5 million for the health system, $5.5 million for payers, and $980,000 to patients over a 120-hour period of service.43 Despite these results, the current, overall role and impact of curbside consultations in cardiology remains to be clarified.
The decision to pursue an informal cardiology consultation in this patient’s case produced several challenges that may have led to the delay in diagnosis and treatment. Due to the nature of curbside consults, clinically significant details and facts may not have been communicated to the consulting cardiologist. Pertinent details that would have been uncovered through medical record review or patient interview were probably missed. With incomplete information, the consulting cardiologist may not have recognized key features of ischemic disease and thus offered generalized (rather than patient-specific) recommendations, missing an important opportunity for early diagnostic testing. Curbside consultations may serve as a useful bridge to formal consultation and expedited care, but this patient unfortunately did not receive timely follow-up. By minimizing this information gap, a formal consultation would likely have prompted a more comprehensive work-up, including an ischemic evaluation, which could have expedited the proper treatment and potentially mitigated a more thorough post-discharge follow-up.
In a busy medical practice, it is tempting to rely on curbside consultations to obtain specialist input in a timely and inexpensive manner, relying on existing social networks and communication mechanisms among physicians. However, this case illustrates the danger in doing so, as key details are inevitably left out of the referring physician’s presentation and the consultant’s impression is clouded by how the referring professional frames the consultation request. For this patient, curbside consultation likely led to an incorrect pre-test probability estimate for an ischemic event and, ultimately, a missed diagnosis.
- Heart disease in women is often under-recognized, under-diagnosed, and under-treated, leading to worsened outcomes that are in part due to insufficient knowledge and awareness of gender differences in cardiovascular disease on the part of treating physicians and other health professionals.
- In the setting of obstructive coronary artery disease, women have worse prognoses than men, higher short- and long-term mortality rates, and substantially higher risk of subsequent MI, heart failure, and death.
- Cognitive biases—availability bias, anchoring bias, confirmation bias, and others—are important contributors to diagnostic errors and can be countered by education of health professionals and use of evidence-based guidelines for disease management.
- Curbside consults are a valuable part of medical practice. However, the decision to pursue an informal consultation can result in challenges that could contribute to a delay in appropriate diagnosis and treatment.
- In a busy medical practice, it is tempting to rely on curbside consultations to obtain specialist input in a timely and inexpensive manner, but key details are inevitably left out of the referring physician’s presentation and the consultant’s impression can be clouded by how the referring professional frames the consultation request.
Amparo C. Villablanca, MD
Director and Founder, UC Davis Women’s Cardiovascular Medicine Program
UC Davis Health
Gordon X. Wong, MD, MBA
UC Davis Health
Acknowledgement: The authors would like to acknowledge the editorial assistance of Saivageethi Nuthikattu, PhD in preparation of this manuscript.
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