UCONN Emergency Medicine Interest Group

Posts Tagged ‘cardiology’

Journal Article Synopsis: Apixaban and ACS

In JOURNAL CLUB on October 30, 2011 at 7:00 AM

Summary of “Apixaban with Antiplatelet Therapy after Acute Coronary Syndrome” by John Alexander et. al, New England Journal of Medicine ePub ahead of print: July 24th 2011: pp. 1-10

What is already known on this topic:
Patients with acute coronary syndromes frequently have recurrent ischemic events despite the use of currently recommended antiplatelet therapy, revascularization procedures, and other evidence based secondary preventative measures. Anticoagulation therapy with oral vitamin K antagonists reduces the recurrence of ischemic events following MI however, when added to aspirin or aspirin and clopidogrel combined it increases the risk of bleeding. Previous studies of the use of the factor Xa inhibitor apixiban were conducted in patients who had recent acute coronary syndrome and were receiving aspirin or aspirin and clopidogrel. Treatment with apixiban resulted in dose related increase in bleeding with a trend towards fewer ischemic events.

What question this study addressed:
Does the benefit of adding apixiban to standard acute coronary treatment outweigh the increased risk of bleeding in high-risk patients?

What was the study design:
The Apixiban for Prevention of Acute Ischemic Events 2 (APPRAISE-2) trial was a double blind, placebo-controlled, randomized clinical trial conducted at 858 sites in 39 countries. Patients included in this study must have had an acute coronary syndrome (myocardial infarction, with or without ST-segment elevation, or unstable angina) within the previous 7 days, with symptoms of myocardial ischemia lasting more than 10 minutes with the patient at rest plus either elevated cardiac biomarkers or dynamic ST-segment elevation or depression of 0.1mV or more. Patients meeting these criteria were eligible for the study if their condition was clinically stable and they were receiving standard treatment for acute coronary syndrome, including aspirin or aspirin and any P2Y12-receptor antagonist. Eligible patients were also required to have two high-risk characteristics which included: an age of at least 65 years, diabetes mellitus, MI within the previous 5 years, cerebrovascular disease, peripheral vascular disease, clinical heart failure or a left ventricular ejection fraction of less than 40% in association with the index event, impaired renal function with a calculated creatinine clearance of less than 60ml per minute, and no revascularization after the index event.

What this study adds to our knowledge:
Administration of apixiban at a dose of 5mg twice daily in high risk patients taking either aspirin or aspirin plus clopidogrel significantly increases bleeding events, including events of fatal and intracranial bleeding, without significant reduction in recurrent ischemic events.

How this is relevant to clinical practice:
The current standard of care for patients after acute coronary syndrome includes dual antiplatelet therapy, usually with aspirin and clopidogrel. Even with this aggressive antiplatelet therapy patients still frequently experience recurrent ischemic events. Newer P2Y12 antagonists are more potent and provide additional reductions in ischemic events and mortality but at the cost of increased risk of bleeding. The combination of antiplatelet and anticoagulant therapy seems attractive, yet it may pose an unacceptable risk of bleeding.

Other considerations:
The population included in the study comprised only high-risk patients, with large proportions of those patients having diabetes, heart failure, or renal insufficiency. The lack of significant reduction in recurrent ischemic events could partially be a product of such a high-risk population. As the authors noted, there may be other patient populations for which the results may be different.

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Pearl/Pitfall: Right-sided MI

In PEARL/PITFALL on July 11, 2011 at 12:40 AM

From didactics with Dr. Regan:

Understanding the presentation of posterior MI on EKG is not that complicated, and need not require any mirrors or special tricks! It can be relatively easily understood simply by recalling the coronary anatomy and lead placement. Remember that anatomically, the right coronary artery takes a path that goes to the posterior portion of the heart, then the inferior portion of the heart. This means that a posterior MI must* have an associated inferior MI; if the inferior leads (II, III, aVF) do not show signs of MI on EKG, then there is no posterior MI. Recall also that the chest leads V1-V6, just like the other leads, measure a vector of electrical activity pointing anteriorly. This implies that the vector goes from posterior to anterior. So, it should be expected that posterior MI should show reciprocal ST-T changes in the anterior chest leads. If they do not, this implies that the MI is a more distal pure inferior MI (which has a significantly better prognosis). If the chest leads do show reciprocal changes, right sided chest leads should be placed to obtain a right-sided EKG to determine if the obstruction is more proximal, resulting in a complete right sided MI, or more distal, resulting in a posteroinferior MI. In other words, the right-sided EKG should demonstrate ST-T changes consistent with MI if there is a complete right-sided MI (eg. ST elevation).  If they do not, the diagnosis is posteroinferior MI (again, remember that a posterior MI requires there to be an accompanying inferior MI).

* Note: as with everything in medicine, there are exceptions to the rule, and so it is possible for variants in coronary anatomy to make this idea not always hold. However, Dr. Regan informs me that he has only seen this occur several times in his nearly 20 years of practicing EM.

** Note: please remember that not all MI present with EKG changes. In fact, the sensitivity of the first EKG in acute MI is only 13-69%, and considering the evolution of all EKG abnormalities (ST, T, Q waves, LBBB) over time, the sensitivity is  87%.

References:
http://www.bestbets.org/bets/bet.php?id=75
http://www.uptodate.com/contents/electrocardiogram-in-the-diagnosis-of-myocardial-ischemia-and-infarction?source=search_result&selectedTitle=4~150

Spotlight Lecture: Chest Pain Risk

In TALKS on June 20, 2011 at 10:53 PM

This is a brief review of a talk given by Dr. David Newman of the SMART EM podcast and thennt.com; it can be found here.

First, as background: the SMART EM podcast is a relatively new EM podcast that does “deep dives” into the EM literature, meaning that they actually look at the primary studies and evidence (or lack thereof) that guide the way that EM is practiced. It is a fantastic listen for anyone that is really interested in practicing evidence-based medicine, and often there are surprising finds that make you take pause.

This talk in particular is about evaluating the risk of chest pain in the ED, and specifically, the 2 patient-oriented outcomes that are important to us: MI, and death (generally within 30 days or 6 months). In brief, there were several important points that were discussed:

1. Framingham risk factors are not useful for predicting the risk of negative outcomes from chest pain except in patients younger than 40 and with >3 risk factors. Dr. Newman makes the point that the Framingham study and the risk factors derived thereof were developed to determine the risk for developing CAD, NOT acute MI.

2. Dr. Newman reviewed several well-done, large, prospective randomized studies that looked at the risk of bad outcome in several cohorts, from low risk chest pain under 40 years old (1:500), low risk chest pain over 40 years old (1:250), and moderate risk chest pain (1:125).

3. It is suggested that these risk statistics can be used to start a conversation with the patient about how to proceed and thus facilitate a shared decision making process.

References

Journal Article Synopsis: Prewired Electrodes for ECG

In JOURNAL CLUB on May 11, 2011 at 5:42 PM

Summary for “Comparison of the Use of Conventional and Prewired Electrodes for Electrocardiography in an Emergency Setting: The Spaghetti Study” by Frederic Lapostolle et al. in Annals of Emergency Medicine Vol 57 (4); pp 357 -361

What is already known on this topic:
ECG’s are a routine procedure commonly encountered in the Emergency Department and integral to the diagnosis and disposition of a wide variety of patients. The two most important factors in the usefulness of an ECG are its quality and the duration of time it takes to be performed. A poorly done ECG done promptly can be just as useless as a well-done ECG received too late. Therefore, improvements in the speed and quality of ECG recording are highly sought after.

The quality and promptness of an ECG are heavily influenced by the user. It is not uncommon for errors to occur in the placement of ECG leads, in particular reversal of the leads. These types of mistakes can lead to a significant loss in time and accuracy of interpretation of ECG’s. Unfortunately, these types of errors are more common in the acute settings, such as those often seen in Emergency Departments. This study involved the use of pre-wired electrodes, rather than conventional electrodes that are placed and then hooked up to the series of wires. These prewired electrodes are disposable, pre-wired, pre-gelled, and numbered for ease and elimination of ambiguity in placement.

What questions this study addressed:
Is there a difference in the quality of ECG recordings obtained with conventional versus prewired electrodes ? How easy is the use of the prewired electrodes in an emergency setting?

What was the study design:
Prospective, randomized, open comparison study including 105 patients undergoing ECG’s. Time to make recordings was measured, and both a prewired and conventional recording was performed. These were then analyzed and scored by 3 blinded reviewers, on the basis of artifacts and baseline instability.

What this study adds to our knowledge:
The ECG’s performed with the prewired electrodes took 20% less time than those done with conventional electrodes (average 118 seconds versus 144 seconds). Signal noise and baseline instability were significantly reduced with prewired electrodes regardless of the endpoint considered (whether number of unstable leads, max signal noise, baseline instability score, etc). There was no significant difference found in the prevalence of p-wave or QRS complex abnormalities.

How this is relevant to clinical practice:
The recordings done with prewired electrodes were accomplished significantly faster than those with conventional – and this did not include the time necessary to disinfect and untangle the lead wires (a daunting task, at times). In addition, recordings with prewired electrodes were significantly better than those made with conventional electrodes. The number of artifact-free recordings was nearly twice as high, and the level of signal noise and baseline instability was significantly lower.

Other considerations:
It would be interesting to examine this from a cost-benefit perspective. Although prewired electrodes are faster and provide better recordings, they are also more expensive – would they pay for themselves with faster and better quality care?

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