EKG Criteria and Identification of Acute Coronary Occlusion

In this retrospective, 2-center, case-control study the investigators will investigate and
compare the accuracy of various ECG criteria and expert interpretation to diagnose Acute
Coronary Occlusion (ACO), with an emphasis on the diagnosis of patients with ACO but without
obvious ST segment Elevation Myocardial Infarction (STEMI) criteria. The investigators will
use two cohorts of patients who present with symptoms consistent with acute MI, one
subsequently proven to have ACO and one proven to not have ACO.

The groups will be identified by chart reviewers who will use all clinical data except the
ECGs to determine, in retrospect, and using strict criteria, if the patient had ACO at the
time of the ECGs to be evaluated, or not. These reviewers will be blinded to all ECGs. The
diagnosis of ACO will be dependent upon angiographic occlusion. Because in many cases of ACO,
the artery spontaneously opens by the time of the angiogram, the investigators will need to
have surrogate endpoints: this will be culprit on the angiogram PLUS a very elevated peak
troponin, as peak troponin I > 10.0 ng/mL and peak troponin T > 1.0 ng/mL are highly
correlated with ACO.

The investigators will find cases of subtle STEMI (ACO without STEMI criteria) by searching
for all myocardial infarction cases that underwent angiography and percutaneous coronary
intervention (PCI). The investigators will attempt by various criteria to determine from all
available sources other than the ECG (angiography, echo, troponins) whether the involved
artery was occluded at the time of the most diagnostic ECG that was recorded while the
patient had symptoms and before the angiogram. Reviewers determining ACO or not ACO will be
blinded to the ECGs. The investigators will use each pre-angiogram ECG, in sequence, for
analysis, to determine if expert interpretation can not only identify occlusion that is not
identified by STEMI criteria, but also to find if expert interpretation can identify
occlusion on an earlier ECG. Expert ECG interpreters will interpret the ECG for evidence of
ACO. Their accuracy will be compared to traditional STEMI criteria and other methods of
interpretation if available.

The investigators will use as controls patients with any ST elevation, or ST depression, of
any etiology that are proven to NOT have occlusion. The investigators will establish absence
of occlusion by a combination of objective data points including angiogram (if performed),
troponins, echocardiograms, clinical course, etc. Details of the methods are below, including
specific outcome definitions used to claim the presence or absence of ACO.

Inclusion Criteria:

- Recorded EKG prior to cardiac catheterization

Exclusion Criteria:

- Absence of documented EKG prior to cardiac catheterization