Friday, March 30, 2012

Glucose-Insulin-Potassium For MI?

"Investigators, led by Dr Harry Selker (Tufts Medical Center, Boston, MA), are pleased with the results, believing that after years of futile study, they have finally found some clinical evidence to support the experimental data suggesting that GIK [glucose-insulin-potassium] myocardial metabolic support could protect the heart in the ACS setting."

...which lead to the press release tweet of "Intravenous GIK Slashes Death Risk in Acute Coronary Syndrome: CHICAGO – Glucose, insulin, and potassium given i..." by @ACEPNews.  That press release can be seen here.

There have been trials enrolling over 20,000 patients to date that have been negative.

Despite all these previous negative trials, the authors believed the problem was timeliness - the critical time in which to provide metabolic support to the infarcting myocardium was in the prehospital setting, upon the earliest recognition of ACS.  The original goal was to enroll 15,450 patients.  They ended up with 880.  Then, after data collection, they changed the primary endpoint from all-cause mortality to progression to myocardial infarction at 30 days and at 1 year.  And they only have the 30 day data right now, they'll get back to us with the 1 year outcomes.  How this made the cut for publication in JAMA is outside the scope of my speculative powers.

So, they enrolled folks prehospital with signs and symptoms of potential acute coronary syndrome whose prehospital EKG was read as STEMI or met the ACI-TIPI prediction instrument probability threshold of 75%.  They received the GIK solution with 90 minutes, on average.  And, the primary outcome measure was negative for progression to MI, trend favoring GIK with OR 0.88 (CI 0.66-1.13).  Negative for 30 day mortality, OR 0.72 (0.40-1.29).  For STEMI patients, negative for progression to MI, OR 0.74 (0.40-1.38), and negative for 30 day mortality, OR 0.63 (0.27-1.49).
So, yes, there is a trend.  And some subgroups even had significant trends in favor of GIK.  But for JAMA and the rest of the internet to be promoting this as practice-changing at this juncture is absolutely inappropriate.

"Out-of-Hospital Administration of Intravenous Glucose-Insulin-Potassium in Patients With Suspected Acute Coronary Syndromes:  The IMMEDIATE Randomized Controlled Trial"

Wednesday, March 28, 2012

CCTA Is A Bad Shortcut Around Bad Care

"Although an acute coronary syndrome is ultimately diagnosed in only 10 to 15% of patients who present with chest pain, the majority of these patients are admitted to hospitals, at an estimated cost of over $3 billion annually."

This is, essentially, the statement of problem from the NEJM article, sponsored by Siemens, regarding the use of coronary CT angiograms in the Emergency Department on low-to-intermediate risk chest pain.  They are clearly huge fans of CCTA up at the University of Pennsylvania, and I hate to think it has something to do with the parade of imaging technology companies and patent applications listed as disclosures by the authors.

In this study, the authors enrolled 1,392 patients with chest pain with the goal of testing the primary hypothesis that "patients without clinically significant coronary disease on CCTA (i.e., no coronary-artery stenosis ≥50%) would have a 30-day rate of cardiac death or myocardial infarction of less than 1%."

Good news!  They were right.  Bad news:  their entire enrolled cohort had a 30-day death or MI rate of only nearly 1%.  It's rather incredible, really, that they have this entire article in which they sing the praises of CCTA for identifying low-risk chest pain, when in reality, they gloss over the fact that they simply could have sent home every single patient in the study without doing a single additional test and only nearly 1% would have had death or MI within 30 days.

Going back to their essential statement of problem, it might be true that CCTA were valuable if they were looking to apply it in a population and practice environment in which we were actually hospitalizing patients with a 10-15% rule-in rate.  However, the opposite of what these authors propose is the real truth - clinically identify all the low-risk chest pain and stop doing all these expensive tests!  They claim it expedites discharge from the Emergency Department, which, in theory, saves money - but it isn't!  Despite 90% of their CCTA being negative for stenosis >50%, they still end up admitting half their CCTA cohort.  Even the negative CCTA cohort, while their length of stay is reduced to 12 hours, still means they're being placed in observation status and billed an additional separate observation code - which in many places is a protocolized chest pain observation unit run by the Emergency Department.

This is simply a bad solution to bad baseline practice patterns.  The measurable benefit here isn't to the patient, it's to the malpractice risk of the physician, to Siemens and other sponsors of the study, and likely to the Emergency Departments whose billing increases for these short stay observation patients.

"CT Angiography for Safe Discharge of Patients with Possible Acute Coronary Syndromes"

Monday, March 26, 2012

Pan-Scan & Zero-Miss

In an interesting contrast to a prior article regarding over-scanning in trauma, this article takes a different perspective.  While the authors do note that there is controversy regarding the impact of "pan scan" on survival, they are rather focused on the sensitivity/specificity of the "pan scan," rather than the appropriateness.

This is a review of 982 consecutive patients undergoing "pan scan" in Germany.  The indications for scanning were a set of "red flag" criteria, which included impaired patients, patients with obvious injuries, "suspicion of severe trauma" or "high risk mechanism".  The diagnostic reference standard was chart review by two reviewers of the electronic notes for any injuries missed on the initial scan.

The results are rather interesting in a couple ways:  the prevalence of injuries per organ system is not terribly high, and the sensitivity of scanning was rather low.  The highest prevalence of injuries for an organ system was 37%, for chest, followed by head and neck at 34%.  However, the sensitivities range from a high of only 86.7% for chest down to a low of 79.6% for face - likely because dedicated fine cuts of the face were not part of their protocol.  Regardless, with sensitivities in the mid-80s meant they missed almost one seventh of the total number of injuries.  Of these 70 missed injuries, almost half required surgery or a critical intervention as treatment.

So, pan-scanning: expensive, low yield, yet still misses important injuries.  The authors do not try to fully address whether their yield is reasonable or not, and wisely simply state further research is needed regarding triaging patients into groups likely to benefit from scanning.

"Accuracy of single-pass whole-body computed tomography for detection of injuries in patients with major blunt trauma."