Friday, May 19, 2017

Hours out of the OR for valve replacement surgery: patient with paced rhythm becomes hemodynamically unstable

This case was sent to me yesterday, coincidentally on the same day we presented data at SAEM on the Utility of the Smith-Modified Sgarbossa Criteria in the Diagnosis of Acute Coronary Occlusion in Ventricular Paced Rhythm.

Sent by Brendan Michael Riordan, a PA working in Cardiothoracic Critical Care:
Twitter: @concernecus

Case

A 73 y/o with hx of bicuspid aortic valve and recent cholecystitis developed increasing shortness of breath and was found to have severe aortic insufficiency as well as complete heart block. He was admitted to the CCU and diagnosed with endocarditis with an aortic root abscess, then taken to the OR where he had a relatively unremarkable operative course for a surgical AVR and aortic root reconstruction (short bypass time, no major arrhythmias, etc.). Post-CPB TEE showed preserved biventricular function (LVEF ~65%) but several distinct RWMA (septal and inferior hypokinesis with paradoxical septal hypokinesis). 

He had an immediate post-op ECG:
There is a ventricular paced rhythm with normal discordant ST segments
No evidence of ischemia



The surgeon attributed the wall motion abnormalities to a small amount of air in the right coronary artery and it improved following a short-term administration of Epinephrine. 

The patient arrived to ICU on no infusions with good hemodynamic parameters. He developed hypoxia and a focused TTE was completed overnight for persistence of this hypoxia, with concern for possible MR causing pulmonary edema, but all of the valve functions were intact. 

Notably though, the LVEF had decreased from 65% to 35% and the previous RWMAs were still present. The patient was started inotropes again to maintain good hemodynamics. 

The next day, the patient remained on inotropes with better oxygenation, but hemodynamics were borderline, and something did not feel right about the clinical situation. The patient remained sedated and intubated and unable to provide any subjective data. 

The original post-op EKG (#1) was reviewed (V-paced), and there was initially some concern that the STE in lead V3 met modified Sgarbossa Criteria for STEMI.  

Smith comment: I don't think so.  I get 3 mm divided by 17, which is a ratio of about 0.17.  This does NOT meet the modified Sgarbossa criteria, but it is a high ratio.  It is important to remember that a normal maximal ratio for V1-V4 is about 0.11.  A ratio of 0.20 (20%) is still fairly specific for coronary occlusion.  As the ratio falls below 0.20, the specificity drops some.  I would not call this positive. 

This was reviewed but not thought to be solid enough evidence. A repeat EKG was recorded:

Thoughts?















Smith comment:  This shows (new) excessively discordant ST Elevation in lead II and V4, and concordant ST Elevation in leads V5 and V6.  This is diagnostic of acute coronary occlusion.



The providers suspected STEMI and though the patient was reliant on pacing for hemodynamics, they briefly turned it off in order to get a 12-lead without pacing:
Now there is complete heart block and bradycardia (the reason for the pacing) and the ST elevation persists in V4-V6.  It is not seen now in lead II.

Case continued

While a non-paced EKG (#3) was performed (the patient had very tenuous hemodynamics without pacing support), a Code STEMI was called. Both General and Interventional Cardiology reviewed the case and determined that there was enough of a good story to warrant a cath. 

Ultimately, the patient was found to have a 100% acute thrombotic occlusion of the RCA, which was stented open with restoration of TIMI 3 flow. The patient made a substantial recovery following intervention. 




STEMI in Ventricular Paced Rhythm

We have some preliminary results of the PERFECT study, presented today at the Society for Academic Emergency Medicine.


The short version: They work!!





Here is the long version

Paced Electrocardiogram Requiring Fast Emergent Coronary Therapy (PERFECT) Study 


ClinicalTrials.gov Identifier:

Performance Characteristics of the Modified Sgarbossa Criteria for Diagnosis of Acute Coronary Occlusion in Emergency Department Patients With Ventricular Paced Rhythm and Symptoms of Acute Coronary Syndrome

Thursday, May 18, 2017
1:39 PM - 1:51 PM
Room: Celebration 14: Convention Level

Kenneth W. Dodd, MD - Hennepin County Medical Center
Kendra D. Elm, MD - Hennepin County Medical Center
Michael Hart, MD - Hennepin County Medical Center
Rehan Karim, MD - Hennepin County Medical Center
Deborah L. Zvosec, PhD - Hennepin County Medical Center
Keith G. Lurie, MD - St. Cloud Hospital/Hennepin County Medical Center
Brett Boggust - Mayo Clinic College of Medicine
Adesola Oje - Thomas Jefferson University
Bayert Salverda - Hennepin County Medical Center
Jennifer L. White, MD - Mayo Clinic College of Medicine
Anna Marie Chang, MD, MSCE - Thomas Jefferson University
Stephen W. Smith, MD - University of Minnesota/Hennepin County Medical Center

Background: The ECG diagnosis of acute coronary occlusion (ACO) in the setting of ventricular paced rhythm (VPR) is purported to be impossible. However, VPR has a similar ECG morphology to LBBB. The validated Smith-modified Sgarbossa criteria (MSC) have high sensitivity (Sens) and specificity (Spec) for ACO in LBBB. MSC consist of ≥ 1 of the following in ≥ 1 lead: concordant ST Elevation (STE) ≥ 1 mm, concordant ST depression ≥ 1 mm in V1-V3, or ST/S ratio < -0.25 (in leads with ≥ 1 mm STE). We hypothesized that the MSC will have higher Sens for diagnosis of ACO in VPR when compared to the original Sgarbossa criteria. We report preliminary findings of the Paced Electrocardiogram Requiring Fast Emergency Coronary Therapy (PERFECT) study (#NCT02765477).
Methods: The PERFECT study is a retrospective, multicenter, international investigation of ED patients from 1/2008 - 12/2016 with VPR on the ECG and symptoms suggestive of acute coronary syndrome (e.g. chest pain or shortness of breath). Data from four sites are presented. Acute myocardial infarction (AMI) was defined by the Third Universal Definition of AMI. A blinded cardiologist adjudicated ACO, defined as thrombolysis in myocardial infarction score 0 or 1 on coronary angiography; a pre-defined subgroup of ACO patients with peak cardiac troponin (cTn) >100 times the 99% upper reference limit (URL) of the cTn assay was also analyzed. Another blinded physician measured all ECGs. Statistics were by Mann Whitney U, Chi-square, and McNemar’s test.
Results: The ACO and No-AMI groups consisted of 15 and 79 encounters, respectively. For the ACO and No-AMI groups, median age was 78 [IQR 72-82] vs. 70 [61-75] and 13 (86%) vs. 48 (61%) patients were male. The median peak cTn ratio (cTn/URL) was 260 [33-663] and 0.5 [0-1.3] for ACO vs. no-AMI. The Sens and Spec for the MSC and the original Sgarbossa criteria were 67% (95%CI 39-87) vs. 46% (22-72; p = 0.25) and 99% (92-100) vs. 99% (92-100; p = 0.5). In pre-defined subgroup analysis of ACO patients with peak cTn >100 times the URL (n = 10), the Sens was 90% (54-100) for the MSC vs. 60% (27-86) for original Sgarbossa criteria (p = 0.25).
Conclusions: ACO in VPR is an uncommon condition. The MSC showed good Sens for diagnosis of ACO in the presence of VPR, especially among patients with high peak cTn, and Spec was excellent. These methods and results are consistent with studies that have used the MSC to diagnose ACO in LBBB.

5 comments:

  1. Thanks for the useful post .
    Apart from this case in which there is recent surgery Would you use fibrinolysis in cases that meet the criteria ?

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  2. Interesting case study with unique evolution in a patient with a pacer. From a qualitative standpoint — I also thought ECG #1 which was completely paced was not diagnostic. Although one might raise questions about the relative amount and shape of ST-T wave change in V3-thru-V6, and especially about the unusual “shelf” of the ST segment in lead V2 — I didn’t think any of these findings were specific enough to call anything acute in a 100% paced tracing. That said, it WOULD have been of interest to have access to a prior completely paced tracing — since IF the above changes were markedly different compared to a prior paced baseline ECG, that might THEN be potentially significant. In contrast, ECG #2 (as noted by Dr. Smith) IS diagnostic for acute STEMI. In addition to satisfying modified Sgarbossa criteria — I’ll emphasize the utility of direct lead-to-lead comparison between ST-T appearance in ECG #2 compared to what it was in ECG #1. There should be no doubt about the new “shelf” of ST elevation (starting from new elevated notched J-points) in each of the inferior and lateral chest leads. Of interest (though I’m not quite sure why) is the finding of upright paced QRS complexes in leads V5,V6 of ECG #2 (whereas the paced QRS was negative in V5,V6 in ECG #1). Finally, for academic interest — I’ll suggest that ECG #3 does NOT reveal complete AV block — because beats #4 and #8 clearly occur EARLY compared to an otherwise regular escape focus. The P wave rhythm that we clearly see in simultaneously-recorded long-lead strips V1, II and V5 at the bottom of the tracing is regular at ~75/minute. If AV dissociation was complete (as it should be with complete AV block) — then one would have expected the escape rhythm to also be at least fairly regular. The fact that especially beat #4 occurs so early — strongly suggests that it IS conducting, most probably with a very prolonged PR interval ~0.84 second (from the on-time P wave that occurs coincident with the end of the QRS of preceding beat #3). This is virtually the same prolonged PR interval that I suspect is conducting beat #8 (from the preceding on-time P wave that occurs shortly after the QRS of beat #7). The fact that morphology for QRS complexes from the 6 other beats look identical to the QRS of these two conducted beats suggests that the site of the escape focus is junctional. This may explain why the relative shape and amount of ST elevation differs in some leads between ECGs #2 and #3 — because QRS complexes in ECG #2 are ventricular paced, whereas they are spontaneous junctional escape beats or conducted beats in ECG #3. BOTTOM LINE: This is a superb case for illustrating how it IS possible to diagnose acute stemi in certain instances of paced tracings. THANKS for presenting this case!

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  3. Excellent case, thanks for the teaching points!!

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