Why ECGs in LVAD Patients Are Not Worthless

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Andrew W Phillips, MD, MEd, FAAEM
Andrew W Phillips, MD, MEd, FAAEM

Chair, AAEM Critical Care Medicine Section
Staff Intensivist, Washington Hospital, Fremont, CA
@warejko
Phillips.EM.CCM@gmail.com

“This is worthless; it looks like someone scribbled on it with a big sharpie marker.”

ECG of a patient with a left ventricular assist device (LVAD). White arrow, pacer spike. Blue arrow, electrical artifact example present in all leads. Blue arrowhead, splintered QRS complex (also called an M wave or W wave).

ECGs in the presence of an LVAD can convey important information. After an LVAD placement, a patient’s ECG undergoes a characteristic and predictable set of changes. While nobody likes adapting to a “new normal,” this shift is conceptually no different than the wide QRS complex seen after pacemaker placement.

Although every patient varies, LVAD ECGs characteristically will have (1):

  • Low limb voltage
  • Electrical artifact in all leads
  • QRS wave splintering
  • More frequent V-pacing

As seen in the figure above, the “thick sharpie” line electrical artifact isn’t actually just a solid smear of black. Look carefully, and it almost looks like centipede legs, which correspond to the RPM of the LVAD (2).

QRS splintering is essentially a shaky QRS complex with several deflections, sometimes termed an M wave or a W wave. The splintering artifact is thought to be a result of scarring around the pump and sutures, which causes changes in the direction of depolarization.

Bearing the baseline changes in mind, we can still garner the most central components of an ECG in a patient with an LVAD: rate and rhythm (3).

  • Rate: QRS complexes remain clearly visible. Thus, variation in the R-R is also visible.
  • Atrial fibrillation: You might not see the P waves well, even in sinus rhythm, but an irregularly irregular series of QRS complexes at a rapid rate is a smoking gun for Afib with RVR.
  • Ventricular tachycardia (VT) and ventricular fibrillation (VF): Even in the presence of M or W waves, the QRS complex is an intact electrical shape. Diagnosing either of these in an unstable LVAD patient is hugely important because they can (and at some point will) impact flow. (The significance of VT and VF with an LVAD is a different topic, but briefly, VF and VT = badness, even with an LVAD.)

Once these arrhythmias are diagnosed, how to deal with them in the presence of an LVAD is described well in this AHA summary.

Ventricular tachycardia in the presence of an LVAD. The electrical artifact is still present, making the VT pattern look like it was scribbled by someone with an unsteady hand. Open Access image by Dr. Venkatachalam Mulukutla et al. Accessed 14 August 2020. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5419334/.
Ventricular fibrillation in the setting of an LVAD. Note how despite the thick tracing, the VF pattern is still clearly discernible. Open Access image by Dr. Peter Mark Schulman. Accessed 14 August 2020. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4120493/.

The other major question physicians use ECGs to answer: Is there a STEMI? Fortunately STEMIs are rare and ACS is uncommon in LVAD patients, but that also means that there is insufficient data to assess sensitivity and specificity of traditional STEMI criteria. A case series of 4 cases produced the answer of: sometimes (4). Additionally, the vast majority of LVAD patients will have a pacemaker, which theoretically means Sgarbossa’s criteria could be applied, but, there is nothing published to date (August 2020) regarding sensitivity and specificity of Sgarbossa’s criteria in the setting of an LVAD. The typical ECG changes seen with LVAD implantation should theoretically not cause false positive STEMI or Sgarbossa criteria changes, so it is worth taking them seriously.

Finally, there’s the experimental stuff. A fascinating study in pigs found that the amplitude of the R wave is associated with left ventricular volume, which could be helpful because getting good echocardiogram windows on patients with an LVAD requires some serious skill. But, this has only been demonstrated in pigs and does not have any clinical outcomes (6).

The Debrief

  • ECGs in the presence of an LVAD have electrical interference but still provide valuable data including rate and dangerous rhythms.
  • Atrial fibrillation, ventricular tachycardia, and ventricular fibrillation are important arrhythmias that can be observed in ECGs in the presence of an LVAD.
Mohamed Hagahmed

Mohamed Hagahmed

Editor’s Commentary by Dr. Mohamed Hagahmed
Review of Godishala et al.4

The authors of the article highlight some of the challenges of correctly identifying ischemia or infarction on the EKG of patients with Left Ventricular Assist Devices (LVADs) who present with chest pain. Patients on LVADs have underlying Heart Failure (HF), which in itself can cause ischemic EKG changes and non-specific aberrations of the ST-T segments and QRS complexes (e.g bundle-branch blocks, left ventricular hypertrophy). Additionally, LVAD’s lead to EKG changes and electrical artifacts, further impairing the recognition of myocardial infarction.

In this case series of four patients who presented with signs and symptoms concerning for Acute Myocardial Infarction (AMI),1 three out of the four patients had new changes on their EKGs when compared with previous baseline studies. These changes were consistent with AMI. Only two of the three patients were promptly diagnosed and referred for emergent reperfusion therapy. The EKG findings of the third patient were less straightforward, and ultimately his symptoms spontaneously resolved during his admission without invasive intervention.

There is a paucity of high-quality studies that clearly evaluate specific EKG findings in LVAD patients with AMI. An important point highlighted in this small case series was the utility of baseline EKGs. In the right clinical setting, new ischemic findings should prompt the clinician to consider AMI and involve the appropriate team early for possible revascularization therapy. Additionally, new or worsening ventricular tachycardia (VT) or ventricular fibrillation (VF) in the absence of a clear precipitant event such as suckdown or electrolyte abnormalities should prompt consideration of ischemic triggers.

References

  1. Martinez SC, Fansler D, Lau J, et al. Characteristics of the electrocardiogram in patients with continuous-flow left ventricular assist devices. Ann Noninvasive Electrocardiol. 2015;20(1):62-68. DOI:10.1111/anec.12181. PMID: 25041228.
  2. Schettle S, Kassi M, Asleh R, et al. LVAD ECG artifact reflecting Heartware pump speed. J Am Coll Cardiol. 2018. 71 (11 Supplement) A816. DOI: 10.1016/S0735-1097(18)31357-3.
  3. Gopinathannair R, Cornwell WK, Dukes JW, et al. Device therapy and arrhythmia management in left ventricular assist device recipients: A scientific statement from the American Heart Association. Circulation. 2019;139:e967-e989. DOI: 10.1161/CIR.0000000000000673. PMID: 30943783.
  4. Godishala A, Nassif ME, Raymer DS, et al. A Case Series of Acute Myocardial Infarction in Left Ventricular Assist Device-Supported Patients. ASAIO Journal. 2017;63(2):e18-24. DOI: 10.1097/MAT.0000000000000401. PMID: 27258219.
  5. Maloy KR, Bhat R, Davis J, Reed K, Morrissey R. Sgarbossa Criteria are Highly Specific for Acute Myocardial Infarction with Pacemakers. West J Emerg Med. 2010;11(4):354-357. PMID: 21079708.
  6. Meste O, Cabasson A, Fresiello L, et al. ECG analysis during continuous-flow LVAD. Computering in Cardiology. 2014; 41:25-28. Available from: http://www.cinc.org/archives/2014/pdf/0025.pdf.

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