UMEM Educational Pearls - By Amal Mattu

Elderly patients are high risk for missed MI because of atypical presentations. Though this seems to be relatively common knowledge, it is not always remembered. So here's a reminder....

• Elderly patients present with chest pain during their MI only ~ 50% of the time
• Dyspnea is the most common anginal equivalent (alternative complaint). Other common anginal equivalents are syncope, nausea, vomiting, or diaphoresis
• The ECG in elderly patients with AMI is more frequently non-diagnostic. Only 40% of the time do they present with a STEMI, and when they do have ST elevation it may be less elevation than with younger patients. Furthermore, baseline abnormalities such as BBB, pacers, and prior MIs may make the ECG more difficult to interpret.

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The most common sources of bacteremia and serious bacterial infections in the elderly are the GU tract, the respiratory tract, and #3-the abdomen.

This third source is a bit of a surprise to many clinicians but worth remembering. Always consider the abdomen as the source of dangerous infections in the elderly when the source is not clearly the lungs or urine!

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Here are a few important points to keep in mind when evaluating elderly patients in the ED or when prescribing a new drug:

• Adverse drug effects lead to 11% of ED visits in patients > 65
• Older patients in the ED generally take > 4 medications per day, with 13% taking > 8 medications
• 11% of elderly patients in the ED receive at least 1 inappropriate medication
• 3 medication classes account for 48% of all ED visits for adverse drug effects in the elderly: oral anticoagulants or antiplatelet meds, antidiabetic medications, and agents with a narrow therapeutic index (e.g. digoxin, phenytoin)

Pay special attention to medication lists and new prescriptions in the elderly....much more attention than with younger patients!

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Clues to RV infarction:

1. This almost always occurs in the presence of a concurrent inferior MI.
2. Clinical findings may include the triad of hypotension, JVD, and clear lungs.
3. ECG clues: in the presence of inferior lead ischemia or injury pattern, look for:
     a. Combination of ST depression in lead V2 + ST elevation in lead V1; OR
     b. Combination of ST depression in lead V2 + isoelectric ST segments in leads V1 and V3; OR
     c. ST elevation in lead III markedly greater than the ST elevation in lead II; OR
     d. ST elevation in right-sided leads (requires you to obtain right-sided leads)

Why is this diagnosis important?
1. It suggests a larger infarction and worse prognosis, so BE AGGRESSIVE in management.
2. Be very cautious with preload-reducing medications (e.g. nitrates) in the acute management of these patients, as they may induce significant reductions in blood pressure and extension of the infarction. Be aggressive with IVF, while maintaining close attention to the lung sounds.

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With recent national shortages of norepinephrine, our typical go-to drug in sepsis, it's become important for us all to familiarize ourselves with alternative pressors in this setting. Phenylephrine is a commonly chosen alternative.

Phenylephrine is a potent alpha-agonist associated with peripheral vasoconstriction. It has no beta effects so it is not associated with tachydysrhythmias. On the other hand, it is associated with reflex bradycardia which can be treated or prevented with atropine (although there are no specific recommendations to routinely administer atropine prophylactically). Phenylephrine may take 10 minutes to demonstrate an effect, and its duration is approximately 15 minutes. It should be used cautiously in patients with underlying cardiac disease because of the vasoconstrictive effect, and it should be avoided in patients with narrow-angle closure glaucoma.

Extravasation can cause tissue necrosis and should be treated with phentolamine.

There has been some controversy regarding the actual clinical benefit of non-invasive ventilation (NIV) for patients with cardiogenic pulmonary edema in recent years. However a recent Cochrane review has confirmed the benefit of NIV for these patients. Early (ED) use of NIV is associated with a decrease in both intubation rates and mortality. The NNT to prevent one intubation is 8, and the NNT to prevent one hospital mortality is 13. To put this in perspective, the NNT for NIV to prevent death in patients with cardiogenic pulmonary edema is lower than the NNT for thrombolytics to prevent death in acute MI.

One key point to remember is that it MUST be used early! If you wait until your patient is decompensating, it is often too late. Start the NIV as soon as possible in these patients.

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DDx for JVD + hypotension + clear lungs:
     RV infarction
     massive PE
     tension PTX (clear lung)
     pericardial tamponade

Assuming your physical exam diagnoses tension PTX, you only need two simple tests to make the diagnosis amongst the other possibilities:
    1.  EKG: RV infarction will almost always show a concurrent inferior MI;
    2.  bedside U/S: tamponade patients have effusion, PE patients have RV distension

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Paroxysmal supraventricular tachycardia (PSVT) is a common tachydysrhythmia encountered in ED practice. PSVT in itself has not been found to be an isolated manifestation of myocardial infarction or unstable angina (i.e. "isolated" = in the absence of other concerning symptoms, such as anginal-type pain, etc.).  Nevertheless, some physicians will routinely test cardiac troponin levels to evaluate for ACS in these patients. We should all remember, though, that tachydysrhythmias including PSVT are a potential cause of elevated troponin levels in the absence of coronary disease, and these elevations do NOT correlate with adverse outcomes unless other concerning symptoms/signs are present as well.

A recent study¹ corroborated this point: 11 out of 38 patients with PSVT had a positive troponin level. Only 2 of the 11 ruled in for ACS, and all of the patients were well at 30 days. Both patients presented with hypotension (SBP in the 70s) and also had other concerning symptoms, such as chest pain (both), dizziness (both), and dyspnea (one).

The takeaway point is simple: if you routinely send troponin levels on your patients for PSVT in the absence of other concerning symptoms/signs, you'll find yourself chasing a lot of false-positive levels.

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Patients with Non-STE-ACS should not be given any NSAIDs aside from aspirin...that includes COX-2 agents. These medications in patients with acute or recent NSTE-ACS have been associated with an increased risk of hypertension, reinfarction, heart failure, myocardial rupture, and death.

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Proton pump inhibitors should be avoided in patients being treated with clopidogrel. PPIs appear to attenuate the effect of clopidogrel, and there's even some suggestion that the addition of PPIs to the medication regimen of patients taking clopidogrel may be associated with an increased risk of rehospitalization or death.

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Prasugrel is a new thienopyridine alternative to clopidogrel and is now listed as an option in the 2011 ACC/AHA Non-STEMI ACS Guidelines. Studies comparing it versus clopidogrel show a slight benefit in terms of adverse cardiac events, but at the expense of a slight increase in bleeding complications. Though the guidelines state no preference between prasugrel vs. clopidogral for NSTEMI ACS patients, prasugrel is finding a role in patients who appear to have a genetic resistance to the effects of clopidogrel (unlikely you'll know this in the ED, but you'll start seeing more patients started on this medication in the outpatient setting).

Prasugrel is contraindicated in patients with a history of TIA or stroke and it should not be given before cath is performed (in contrast, some protocols push for clopidogrel as early as possible, even before cath).

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Therapeutic hypothermia in post-cardiac arrest patients with return of spontaneous circulation + coma (GCS < 8) is now well-accepted, and the current recommendations are for continued sedation of these patients. Consider avoiding the use of midazolam for sedation in these patients. Midazolam is metabolized more slowly in hypothermic patients, resulting in accumulation and the potential for longer ventilation and ICU time.

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It is now well-accepted that induction of hypothermia should be initiated in victims of cardiac arrest who regain spontaneous circulation and remain unresponsive. Studies are now being performed and published that suggest that the earlier that hypothermia is induced, the better the neurological outcome. With this in mind, some experts are now recommending that cool IVF be the initial resuscitation fluid that these patients receive when resuscitation is initiated. It appears that aggressive use of cool IVF right from the initiation of attempted resuscitation results in improvements in survival to hospital admission and discharge.

The bottom line here is that when caring for victims of primary cardiac arrest, we should be certain to cool the patients fast and early!

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Beck's triad is well known to many physicians, but here's some simple things you may not have known.

Beck actually described two triads, one for acute and one for chronic tamponade.
The triad for chronic tamponade consists of increased CVP (JVD), ascites, and a small quiet heart (muffled heart sounds).
The triad for acute tamponade consists of JVD hypotension, and muffled heart sounds.

Almost 90% of patients have at least 1 of the signs, but only one-third have all 3. Furthermore, it appears that the simultaneous occurrence of all 3 signs is a very late manifestation of tamponade, usually preceding cardiac arrest.
 

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Cocaine-associated MI occurs fairly early after acute cocaine use. 50% of MIs occur in patients prior to their arrival in the ED, and 24% of the total will occur within the first hour of cocaine use. If a patient has not ruled in by 12 hours post-arrival in the ED, it is extremely unlikely that the patient will rule in or suffer ACS-related complications from the cocaine....thus the concept behind using rapid rule out protocols in these patients.

The most important thing we as physicians can do for these patients is to strongly emphasize discontinuation of cocaine use and refer to rehab whenever possible. If the patient discontinues using cocaine, the prognosis for absence of subsequent cardiac events is excellent.

[thanks to Dr. Ellen Lemkin for her contribution to this pearl}

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Traditional teaching for many years has been that new or presumed new LBBB in patients with anginal type of symptoms should be treated as a STEMI, i.e. with immediate PCI or lytics. However, that teaching is based on poor evidence. Newer, increasing evidence is suggesting that new/presumed new LBBB in patients with anginal symptoms is actually not associated with acute MI any more often than when a patient has an old LBBB with those symptoms.

Probably the best management in patients with anginal type of symptoms and a new/presumed new LBBB is to contact the cardiologist on call and ask them for their preference in terms of treatment. Those patients are not necessarily definite AMIs.

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Dabigatran is a new oral anticoagulant (direct thrombin inhibitor) which is being marketed as the new drug to replace warfarin in many cardiac patients. You'll hear much more about it in the coming year, but for now you should know the main advantage and disadvantage:
1. advantage: no need to check levels, e.g. INRs
2. disadvantage: no reversal agent; if a patient is actively bleeding, all you can do is to hold further doses and provide supportive therapy, e.g. tranfusions; hemodialysis is another option, but not ideal to place new dialysis catheters emergently in patients that are coagulopathic!

This second point, the disadvantage of having no reversal agent, is potentially a big issue, especially in older patients at risk for falls. Stay tuned for more information...

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We already know that polypharmacy is a big issue in the elderly, but here are a few key points to keep in mind:
1. Adverse drug effects are responsible for 11% of ED visits in the elderly.
2. Almost 50% of all adverse drug effects in the elderly are accounted for by only 3 drug classes:
     a. oral anticoagulant or antiplatelet agents
     b. antidiabetic agents
     c. agents with narrow therapeutic index (e.g. digoxin and phenytoin)
3. 1/3 of all adverse-effect-induced ED visits are accounted for by warfarin, insulin, and digoxin.
4. Up to 20% of new prescriptions given to elderly ED patients represents a potential drug interaction.

The bottom line here is very simple--scrutinize that medication list and any new prescriptions in the elderly patient!

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Severe hemolysis/hemolytic anemia in a patient with a prosthetic cardiac valve suggests a paravalvular leak. In this condition, a portion of the valve becomes dislodged from the valve annulus. It can occur immediately after surgery or delayed if from endocarditis. Paravalvular leaks are more common with mechanic valves. Patients may also present with sudden pulmonary edema.

The treatment will focus on management of the pulmonary edema and prompt surgical repair.

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Aortocaval compression occurs often when gestational age is > 20 weeks. This compression significantly compromises the chances of maternal survival in cardiac arrest. Because it is often difficult to know the exact gestational age, it is commonly recommended that emergency C-section in maternal cardiac arrest be performed when the fundus extends above the level of the umbilicus.

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