Friday, July 27, 2012

Predicting sICH in Thrombolysis

In contrast to the lunacy of IST-3, this is another piece of work that at least in the right direction – helping us avoid harming patients with thrombolysis.  

These authors use the Get With The Guidelines registry as their derivation and validation group to develop a prediction rule for sICH in the setting of thrombolytic use for acute ischemic stroke with in 3 hours of symptom onset.  Subsequently, they "externally validate" their rule by applying it retrospectively to the NINDS data set.  At the end of it, they come up with a not-so-handy point scale with six clinical features and twenty discrete elements, but basically, these things are bad:
 - Older patients
 - More severe strokes
 - Higher systolic blood pressure
 - Elevated blood glucose
 - Asian ethnicity
 - Male gender

The C-statistic was .71 on their derivation cohort, .70 on their validation cohort, and .68 on the NINDS cohort - which is more or less just OK.  In practical, clinical terms, their tool more or less discriminates between folks who are at 1-3% risk of ICH, and then 6-10% risk of ICH.  And, I think it's extremely valuable when discussing risks with our patients to not use blanket generalities, and attempt to tailor the discussion to the individual.

"Risk Score for Intracranial Hemorrhage in Patients With Acute Ischemic Stroke Treated
With Intravenous Tissue-Type Plasminogen Activator" 

Wednesday, July 25, 2012

Anterior STEMI or Benign Repolarization?

As requested by @jord7an, this covers Dr. Smith's recent Annals publication regarding the differentiation of anterior STEMI from early repolarization abnormalities.  Classically, early repolarization abnormalities manifest with prominent R waves, J-point elevation, ST-segment elevation, and a concave ST-segment morphology in the precordial leads.  However, physician performance in practice at differentiating this pattern from true STEMI could be better, with benign repolarization making up about 10% of anterior STEMI cath lab activations.

In short, this is a retrospective evaluation of electrocardiographic features of anterior STEMI, trying to find an accurate, reliable rule to diagnose STEMI rather than a similar "pseudoinfarction" pattern.  After doing objective measurements of several possible criteria between their comparison sets of "subtle" anterior STEMI and early repolarization, they come up with this rule:

            (1.196 x STE60 V3) + (0.059 x QTc) – (0.326 x RA V4)

If the result of that equation is calculated as >23.4, there's a +LR of 9.2 for STEMI, and a -LR of 0.1 if negative.  And, those are useful LRs.

So, this is probably helpful.  The authors suggest this could be easily programmed into the automatic rhythm analysis software of ECG machines, which is plausible.  This is, however, a retrospective derivation study.  The next step, ideally, would be a prospective comparison between rule-augmented clinical decision-making and non-augmented decision-making.  Unfortunately, detecting small differences in clinical performance may require large samples, and these clinical dilemmas are not common at single centers.

"Electrocardiographic Differentiation of Early Repolarization From Subtle Anterior ST-Segment Elevation Myocardial Infarction"

Monday, July 23, 2012

The Wrong Way To Quit Drinking

This week's NEJM Case Records is an Emergency Department & Toxicology patient – I won't ruin the final diagnosis for you – who uses a mysterious South American alcoholism cure to attempt to rehabilitate himself after a night of heavy drinking.

Obviously, it wouldn't be a case report if the patient in question didn't end up in the ICU!  There are nice, educational discussions of several toxodromes, antidotes, and various options for preventing end-organ damage in a subset of uncommonly seen poisonings.

"Case 22-2012: A 34-Year-Old Man with Intractable Vomiting after Ingestion of an Unknown Substance"