A 77 yo woman with h/o pacer for unknown reasons (no medical records available) and no h/o coronary disease presented with 24 hours of constant chest pain. She decided to call 911 because she just couldn't walk any more. Paramedics found her with normal vital signs, chest pain 8/10, and the following ECG:
I was worried that she had suffered a very large MI because her pain had lasted so long. It did decrease to 3/10 after sublingual NTG. She arrived in the ED and had the following ECG at 1030:
The troponin I returned at 12 ng/ml. I was relieved that it was not much higher. I gave her ASA, clopidogrel, and heparin and she went immediately to the cath lab and had an active ostial LAD lesion with a long hazy calcified segment that could not be stented. She went for 2-vessel CABG.
Here is an ECG from 1530:
Echo showed an inferoposterior and a probable anteroapical wall motion abnormality.
She did well.
Addendum:
Here is an addition to this post in response to a question/comment: "I am sorry to say that I do not find any literature about that topic. Therefore I kindly ask, why you comment on the dynamic ST-segment changes in this patient as a typical sign of acute MI. Could you comment on this or give additional literature."
I was worried that she had suffered a very large MI because her pain had lasted so long. It did decrease to 3/10 after sublingual NTG. She arrived in the ED and had the following ECG at 1030:
The troponin I returned at 12 ng/ml. I was relieved that it was not much higher. I gave her ASA, clopidogrel, and heparin and she went immediately to the cath lab and had an active ostial LAD lesion with a long hazy calcified segment that could not be stented. She went for 2-vessel CABG.
Here is an ECG from 1530:
There is some continued dynamism of the T-waves |
Echo showed an inferoposterior and a probable anteroapical wall motion abnormality.
She did well.
Addendum:
Here is an addition to this post in response to a question/comment: "I am sorry to say that I do not find any literature about that topic. Therefore I kindly ask, why you comment on the dynamic ST-segment changes in this patient as a typical sign of acute MI. Could you comment on this or give additional literature."
There
is some previous literature on this, but not a lot. I have summarized the most recent article
below. There is also one from the 90’s,
referenced here.1
There
is little reason to suspect that paced rhythms act any differently than left
bundle branch block or, if the activation is from the left, like RBBB. In my experience of multiple cases (see here for a
couple), and of cases of PVC’s (see here
and here),
concordant ST segments and excessively discordant ST segments (> 25% of the
preceding S-wave or R-wave, as measured at the J-point) are very good for
injury. Even better are dynamic ST
segments, as in this case. There is no
way for pacing alone to result in dynamic ST segments; one must assume dynamic
ischemia until proven otherwise.
This
is the more recent article: Maloy et al.(Maloy 2011)2 assessed the Sgarbossa criteria1 in 57 cases of paced ECG in
biomarker-diagnosed AMI (not angiographic occlusions), and compared them to 99
troponin-negative paced controls who were otherwise of comparable age and
sex. There were no cases of concordant
ST elevation. Concordant ST depression
in one of leads V1-V3 had sensitivity
of 19% (95% CI 11–31%) and specificity 81% (95% CI 72–87%). For ST-segment elevation >5mm and
discordant with QRS complex, the sensitivity was 10% (95% CI 5–21%) and
specificity 99% (95% CI 93–99%). The
authors do not publish the numbers of patients who met each criterion. Only one patient (a control) met both
criteria, so it appears that the sensitivity of the overall rule was 29%. Given that only about 30% of
troponin-diagnosed AMI are STEMI-equivalents (occlusion or near occlusion, as
opposed to Non STEMI), this is surprisingly high sensitivity for a group that
had no concordant ST elevation.
1. Sgarbossa EB, Pinski SL, Gates KB,
Wagner GS. Early electrocardiographic diagnosis of acute myocardial infarction
in the presence of ventricular paced rhythm.
GUSTO-I investigators. Am J Cardiol 1996;77(5):423-4.
2. Maloy
KR, Bhat R, Davis J, Reed K, Morrissey R. Sgarbossa Criteria are Highly
Specific for Acute Myocardial Infarction with Pacemakers. The western journal
of emergency medicine 2011;11(4):354-7.