#450 Acute Coronary Syndrome with Dr. Sanjeev Francis – Part 1

August 26, 2024 | By Meredith Trubitt

Audio

Video

Transcript available via YouTube

Quit playing games with my heart

Don’t skip a beat and join us  in part 1 of our conversation with cardiologist  Dr. Sanjeev Francis (@, Maine Medical Center)for acute coronary syndrome. First up, the basics on physical exam, how to interpret high-sensitivity troponin and how to think through the spectrum of acute coronary syndrome.

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Show Segments

• Start Part 1
• Intro
• Rapid fire questions/Picks of the Week
• Case 1
• History and Physical
• ECGs 
• Definitions
• Risk Stratification Tools
• Non-invasive Testing Options
• End Part 1
• Start Part 2
• Case 2
• Warranty on Non-invasive Testing
• Invasive Management of non ST elevation ACS 
• Medical Management of non ST elevation ACS 
• Case 3
• Myocardial Injury Definitions
• Diagnostics to Consider for Myocardial Injury
• Transitions of Care
• Outro
• End Part 2

Acute Coronary Syndrome Pearls

1. Carotid auscultation is a good physical exam maneuver to quickly assess for bruits and determine if a patient has atherosclerosis. If present, this may place acute coronary syndrome higher on your differential.
2. ST elevation in lead aVR or ST depressions in other leads are highly suspicious for atherosclerosis.
3. The 5th-generation troponin assay (high-sensitivity troponin) detects lower levels of circulating troponin than prior assays, which allows detection of myocardial injury. 
4. Coronary CTA is an emerging modality to assess coronary circulation – it can estimate FFR (fractional flow reserve), which previously required catheterization to assess stenoses. 
5. Patients with NSTEMI may warrant urgent catheterization if they develop hemodynamic instability, refractory chest pain, or recurrent or dynamic ECG changes.”
6. Cardiac rehab is highly effective for preserving functional status and should be recommended for everyone after an acute coronary event.

Acute Coronary Syndrome

Definitions

Acute coronary syndrome encompasses the spectrum of diseases which cause a sudden reduction in blood flow to the heart, leading to myocardial injury or ischemia. The 2023 ESC Guidelines focus on management of the ACS spectrum from unstable angina to STEMI (Byrne, 2023). The 2021 ACC/AHA Guidelines focus on risk stratification of patients with chest pain into low, intermediate, or high-risk categories (Gulati, 2021). Based on this initial risk assessment, patients may require further evaluation in line with the ESC Guidelines. 

The 2021 ACC/AHA Guidelines for Evaluation and Diagnosis of Chest Pain recommend using broad terminology such as “chest discomfort” (as opposed to “chest pain”)  to describe patients who may be having an ischemic event. Additionally, they recommend against the term “atypical chest pain,” which is vague and misleading, in favor of the more precise “cardiac,” “possibly cardiac,” or “noncardiac” to describe chest discomfort (Gulati, 2021). 

History and Physical

Some features which suggest chest discomfort is ischemic in nature are if it is central, pressure-like, squeezing, gripping, a heaviness, tightness, exertional, or retrosternal. Conversely, words such as sharp, fleeting, shifting, pleuritic, or positional, suggest alternative etiologies (Gulati, 2021). 

In considering alternative etiologies, Dr. Francis recommends vigilance for “can’t miss” diagnoses, including pulmonary embolism and acute aortic syndrome. Once these have been ruled out, consider the patient’s risk factors for acute coronary syndrome, including hypertension, hyperlipidemia, diabetes, a family history, and tobacco use disorder. 

Contrary to the old dogma that women present differently from men with ACS, recent studies suggest that women and men present with similar symptoms (Lichtman, 2019; Hermal, 2017). Of note, the guidelines recommend cultural competency training to improve outcomes of patients presenting from diverse backgrounds (Gulati, 2021). 

Regarding the physical exam, Dr. Francis recommends doing a brief, complete cardiac assessment of the patient. This should include auscultation for carotid bruits: the carotids are the most easily accessible vessels for auscultation, so if a bruit is heard, it signifies that this patient has atherosclerosis, and may have a higher likelihood for coronary atherosclerosis (expert opinion). Dr. Francis also recommended checking for symmetry of pulses to ensure that an acute aortic syndrome is not missed. 

ECG and Biomarkers

ECG

Any patient presenting to the ER with chest discomfort should have a 12-lead ECG performed within 10 minutes of arrival (Gulati, 2021; Byrne, 2023). A non-diagnostic ECG does not rule out acute coronary syndrome in all cases: for example, dynamic changes on repeat ECGs may reveal evolving ischemia, and additional precordial leads may reveal a posterior myocardial infarction (MI) (Gulati, 2021; Byrne, 2023). 

Dr. Francis reviewed the following ECG findings and ranked them from most to least concerning: 

• ST Elevation: ST elevations in a territorial distribution suggest myocardial injury and should prompt a decision on cath lab activation or administering thrombolytics for immediate reperfusion. 
• Left Bundle Branch Block (LBBB): New LBBB is considered a STEMI equivalent in someone with acute chest discomfort. If you are uncertain as to whether a LBBB in a patient with ischemic symptoms is new, assume it is new to ensure proper evaluation. 
• Q waves: similar to ST elevations, Q waves in a coronary territory indicate ischemia has occurred. Q waves can form within hours of an ischemic event and can exist concurrently with ST segment changes. 
• ST depression: Deeper and more downsloping ST depressions, especially in a coronary territory, are worrisome for ischemia. Diffuse ST depressions combined with ST elevation in lead aVR suggest global ischemia (Nabati, 2016). 
• Right Bundle Branch Block (RBBB): New RBBB is not considered a STEMI equivalent, but could mask other ischemic findings, so further work-up typically required (Byrne, 2023). 
• T wave abnormalities: T wave abnormalities are common but non-specific. Peaked or deep T waves or dynamic changes should prompt further evaluation. 
• Unremarkable ECG: A normal ECG does not rule out ischemia, for example, early on in ACS, or in a posterior infarction (Gulati, 2021; Byrne, 2023).

Because dynamic ECG changes can happen within minutes, use repeat ECGs when the diagnosis is uncertain. This information can be particularly valuable while awaiting biomarker results or when there has been a clinical change (Byrne, 2023). 

Troponin and High-sensitivity Troponin

There are three forms of troponin: T, C, and I. Troponin T and I are highly specific and sensitive for detecting damage to cardiac myocytes (Garg, 2017). Prior to development of high-sensitivity troponin (5th generation) assays, troponin levels below the limit of detection were considered negative for ischemia (Garg, 2017). However, the higher precision of current tests allows for better quantification and classification of patients into three categories: normal levels of troponin, abnormal troponin suggesting cardiac damage due to causes other than ACS, and abnormal troponin suggesting myocardial necrosis (Garg, 2017). 

The 2023 ESC Guidelines for Management of Acute Coronary Syndrome now recommend using a high-sensitivity troponin assay to evaluate patients with chest pain,  if available. For patients with normal initial values, repeat assessments to look for a “delta” in troponins 1-2 hours later should be performed (Byrne, 2023). 

Risk Stratification Scores

Several risk stratification tools to estimate morbidity and mortality from ACS have been developed. All use a combination of history, initial ECG findings, and biomarkers to determine risk. 

• HEART Score
• TIMI Risk Score for Unstable Angina and NSTEMI
• GRACE 

Imaging

Low-risk patients should receive counseling on risk factor modification and outpatient re-assessment with non-invasive tools like the coronary calcium scores. High-risk patients typically need invasive evaluation with cardiac catheterization. Intermediate-risk patients should undergo anatomic or functional testing tailored to the individual patient: consider their ability to exercise, radiation exposure, body habitus for image capture, and institutional expertise and access (Gulati, 2021).

Anatomic Testing

• Coronary CT Angiography: Coronary CT can diagnose and estimate the extent of coronary artery disease. Dr. Francis highlights its ability to measure fractional flow reserve (FFR), providing an estimate of the severity of disease in a vessel. Contraindications include: iodine allergy, inability to cooperate with instructions, clinical instability, renal impairment,beta blocker and/or nitroglycerin intolerance, marked heart rate variability due to arrhythmia (Gulati, 2021). Dr. Francis notes that  coronary CT angiography is only useful in patients who have not previously undergone revascularization of any kind. 
• Invasive Coronary Angiography (catheterization): Catheterization measures the severity of coronary obstruction and allows simultaneous intervention on lesions amenable to angioplasty and/or stenting (Gulati, 2021).

Diagnostic Testing

• Exercise Treadmill Test: An exercise treadmill test can detect ischemic symptoms, ECG changes, or a drop in blood pressure with exercise. Contraindications include: baseline abnormal ECG (especially near ST segment), inability to achieve 5 METs, high-risk unstable angina or acute MI, uncontrolled heart failure, cardiac arrhythmias, severe symptomatic aortic stenosis, severe systemic arterial hypertension, and acute illness (Gulati, 2021).
• Echocardiography: Traditional echocardiography allows evaluation for alternative causes such as aortic dissection, pericardial effusion, stress cardiomyopathy, hypertrophic cardiomyopathy, as well as assessment of left ventricular and right ventricular function (Gulati, 2021). Additionally, it can be helpful in an acute coronary syndrome to assess for wall motion abnormalities and the degree of left ventricular dysfunction (Byrne, 2023). 
• Stress echocardiography: Stress echo can be used to define ischemia severity or for risk stratification. Contraindications include: poor windows, inability to reach target heart rate, uncontrolled heart failure, high-risk unstable angina, active ACS, arrhythmias (ventricular arrhythmias, AV block, or uncontrolled AF), respiratory failure, severe COPD, acute PE , severe pulmonary hypertension, contraindications to dobutamine or atropine, critical aortic stenosis, acute illness, hemodynamically significant LV outflow tract obstruction, and severe hypertension (Gulati, 2021).
• Stress Nuclear (PET or SPECT) Myocardial Perfusion Imaging: These tests assess perfusion abnormalities, left ventricular function, and transient ischemic dilation. PET allows calculation of myocardial blood flow reserve, while SPECT MPI does not. Contraindications include: high-risk unstable angina, ACS complicated by arrhythmia or heart failure, contraindications to vasodilators, regadenoson, or adenosine; severe hypotension or hypertension, COPD or asthma, and recent use of dipyridamole or methylxanthines (Gulati, 2021).
• Cardiac MRI: Cardiac MRI assesses global and regional left and right ventricular function, localizes myocardial ischemia or infarction, and measures myocardial viability. MRI can help differentiate acute from chronic ischemia. Contraindications include: reduced GFR, inability to tolerate vasodilators, implanted devices, claustrophobia, and recent caffeine. (Gulati, 2021).

THIS CONCLUDES PART 1, the following is from PART 2.

“Warranty” on Tests

Dr. Francis says the “warranty” for a high-quality negative coronary CT is about two years, meaning you can treat a negative test obtained any time in the last 2 years as current. For all other testing modalities, the “warranty” is shorter, on the order of one year. However, recognize that plaque rupture is unpredictable, so patients presenting with concerning symptoms during the “warranty” period may still need further work-up (Gulati, 2021).

Cardiac Catheterization

Patients with STEMI need prompt cardiac catheterization and revascularization. If revascularization is not available at your institution, then administration of thrombolytics and initiating transfer to a facility that can perform catheterization are indicated (Byrne, 2023).

Patients with NSTEMI need further evaluation to determine timing of cardiac catheterization. High-risk features that should prompt catheterization within 24 hours include “confirmed diagnosis of NSTEMI based on high-sensitivity troponin algorithms, dynamic ST segment or T wave changes, transient ST segment elevation, or a GRACE risk score > 140.” Very high-risk features that should prompt emergent catheterization include diagnosis of NSTEMI and “hemodynamic instability or cardiogenic shock, recurrent or ongoing chest pain refractory to medical treatment, acute heart failure presumed secondary to myocardial ischemia, mechanical complications, and recurrent dynamic ECG changes suggestive of ischemia” (Byrne, 2023). 

If cardiac catheterization is not available in your facility, plan for early initiation of transfer of high-risk patients with NSTEMI to a capable facility, and use serial ECG and biomarker determinations to monitor evolution of ACS. 

Medical Management

Aspirin

All patients with suspected acute coronary syndrome should receive a one-time loading dose of aspirin 325 mg, followed by a maintenance dose of 81 mg daily (Byrne, 2023). Dr. Francis reminds us that if you are unsure whether a patient received a loading dose, give it again. 

Statins

A lipid panel can be falsely low during the acute coronary event, so it may not provide meaningful data. As lipid lowering slows long-term plaque progression, most patients should start lipid-lowering agents during the index hospitalization if not already on them (Byrne, 2023). The high-intensity options are atorvastatin 40 mg or 80 mg daily and rosuvastatin 20 mg or 40 mg daily (Dr. Francis recommends the higher doses since doses can be reduced as an outpatient if the patient achieves marked LDL lowering). Second agents are reserved for patients with suspicion of familial hypercholesterolemia or those already on high-intensity statins prior to hospitalization. 

P2Y12 Inhibitors

There are three options for P2Y12 inhibitors: clopidogrel, ticagrelor, and prasugrel. All three utilize a loading dose followed by a maintenance dose. A common practice of loading all patients with ACS with a P2Y12 inhibitor came from studies in an era when catheterization may not occur for several days. Given improvements in the timeliness of catheterization and the downside of delaying surgical revascularization if indicated, guidelines no longer recommend P2Y12 inhibitor loading prior to catheterization. However, if for any reason an extended delay in catheterization is anticipated, loading with a P2Y12 inhibitor should be considered (Byrne, 2023).  

Anticoagulation

All patients with ACS should initiate parenteral anticoagulation. Unfractionated heparin (UFH) is favored in those undergoing cardiac catheterization with possibility of angioplasty/stenting. Low molecular weight heparin (LMWH) and bivalirudin are alternatives for patients with STEMI. Fondaparinux is recommended as an alternative to UFH for patients with NSTEMI who are not expected to undergo early angiography (Byrne, 2023). Patients on oral anticoagulants for other diagnosis should have their oral anticoagulants held and should be transitioned to UFH during ACS (Byrne, 2023). 

Nitrates

Sublingual nitroglycerin is the first-line therapy for pain management in suspected ACS. If pain is relieved by nitroglycerin, guidelines recommend repeated ECGs to assess for improvement of any ST changes, which should increase your suspicion for ACS. If pain returns, longer-acting formulations delivered as a paste or intravenous infusion can be used. Contraindications to nitrates include: “hypotension, marked bradycardia or tachycardia, right ventricular infarction, known severe aortic stenosis, or phosphodiesterase 5 inhibitor use within 24-48 hours” (Byrne, 2023).

Beta Blockers

Beta blockers, which slow the heart rate and decrease myocardial work, are effective anti-anginal drugs. Dr. Francis recommends using metoprolol tartrate which is easily titratable every 6-8 hours to lower heart rates. It can be especially beneficial in patients with LVEF <40% (Byrne, 2023), but in the acute setting should be used with caution if there is concern for low cardiac output.  

Morphine

Morphine may be used as a supplemental analgesic for pain that persists despite nitrates and beta blockers; however, be vigilant for ongoing ischemic symptoms that may warrant expedited catheterization. Additionally, opioids can slow gut motility, which may delay antiplatelet therapy absorption (Byrne, 2023).

Myocardial Injury

This is a relatively new concept in the era of high-sensitivity troponins. For example, patients with noncardiac conditions like infections or renal failure commonly have elevated high-sensitivity troponins in the absence of ACS. Any elevated troponin, whether acute (i.e. sepsis, atrial fibrillation) or chronic (ESRD, hypertensive heart disease, cardiomyopathy) portends a poor prognosis compared with patients without elevated troponins (Gulati, 2021). 

Dr. Francis recommends an echocardiogram during the inpatient stay for most patients with myocardial injury. If a chest CT was performed for any reason, you can review this for evidence of coronary calcifications. Clear abnormalities on either of these tests should prompt further work-up during hospitalization. If these studies are equivocal or normal, Dr. Francis recommends outpatient evaluation after the acute illness has resolved (expert opinion). 

Transitions of Care

Patients with ACS should follow up with an outpatient cardiologist and their primary care provider until the outpatient management plan is determined and can be maintained by the PCP. Patients with myocardial injury (but not ACS) may follow up with their primary care provider until further testing has been completed that can help determine the need for cardiology follow-up.

Cardiac rehab is a cornerstone of post-acute cardiac care we should recommend to all patients with ACS. While insurance and distance remains a barrier, its mortality benefit is large (Byrne, 2023). 

Physical activity after ACS can be challenging, but patients should slowly increase physical exercise based on their tolerance with the goal of increasing exercise capacity. Guidelines note that self-guided physical activity does not replace the benefit of cardiac rehab (Byrne, 2023).

Links

1. Cross Country Skiing
2. Teethers 

Goal

Listeners will create a framework for diagnosis and treatment of ACS in the hospitalized patient. 

Learning objectives

After listening to this episode listeners will…  

1. Recognize the clinical presentation of ACS, including the spectrum of symptoms (e.g., chest discomfort, pressure, shortness of breath) and the importance of a thorough history and physical examination in diagnosis.
2. Implement risk stratification tools (e.g., HEART score, TIMI score, GRACE score) to assess the risk of adverse outcomes in patients with suspected ACS and guide management decisions.
3. Describe the principles of initial management of ACS, including the use of aspirin, P2Y12 inhibitors, anticoagulants, nitroglycerin, and beta-blockers.
4. Evaluate the indications and timing for invasive procedures such as coronary angiography and percutaneous coronary intervention (PCI) in the management of ACS.
5. Discuss the role of medical therapy (e.g., aspirin, statins, beta blockers) and cardiac rehab in secondary prevention following an ACS event.

Disclosures

Dr. Sanjeev Francis reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures. 

Citation

Amin, M, Trubitt, M, Coleman C, Francis S, Williams PN, Watto MF. “#450 Acute Coronary Syndrome with Dr. Sanjeev Francis”. The Curbsiders Internal Medicine Podcast. thecurbsiders.com/category/curbsiders-podcast August 26, 2024.