One of the dreaded complications during STEMI is the occurrence of VF.
So are there any predictors that we can count on?
Yes, and one of the better predictors is via ECG.
The amount of ST elevation can be useful according to Demidova MM et.al. In their study, they found out that sum of ST-segment deviations in all leads >1500 μV (odds ratio 3.7, 95% confidence interval 1.45 to 9.41, p = 0.006) before PCI remained an independent predictor of rVF after multi-variate analysis.
How much is 1500 uV?
Normally STEMI diagnosis is made when there is > 1 mm ST elevation in 2 limb leads or > 2 mm ST elevation in > 2 adjacent precordial leads.
- 1 mm = 0.1 mV = 100 uV
- So 1500 uV = 1.5 mV = 15 mm
So a sum of ST segment deviations of 15 mm is an independent predictor of VF during reperfusion according to their study.
In my further googling I found an interesting article that further (in my opinion) reaffirms this finding – the so called Lamda-like wave.
- It was first described in a young patient with SCD, then subsequent it was also found that patients with AMI would also have Lamda-like wave.
- The importance of this wave is its association with occurrence of VF.
- Due to similar morphology, it was hypothesized that AMI perhaps share the same mechanism with Brugada syndrome.
Notice the massive ST elevation?
– Regardless of the name given to this ST segment, I think massive STE is a high risk to developing VF in AMI.
Similarly, high STE is also a bad thing in NON-MI patient. Look at this so-called spiked helmet sign in a patient with bowel perforation. Subsequently, this patient died despite agressive surgical and medical treatments.
The amount of ST elevation is a predictor of VF in AMI patients.
– Perhaps in non-AMI patients, high ST elevation may also be a predictor of poor prognosis.
- Predictors of ventricular fibrillation at reperfusion in patients with acute ST-elevation myocardial infarction treated by primary percutaneous coronary intervention.
Demidova MM, Carlson J, Erlinge D, Platonov PG
Am J Cardiol. 2015 Feb 15;115(4):417-22.
- The “Spiked Helmet” Sign: A New Electrocardiographic Marker of Critical Illness and High Risk of Death
Laszlo Littmann, MD, PhD and Michael H. Monroe, MD
Mayo Clin Proc. 2011 Dec; 86(12): 1245–1246.
- Lambda-like ST segment elevation in acute myocardial infarction – a new risk marker for ventricular fibrillation? Three case reports.
Piotr Kukla, Marek Jastrzębski, Jerzy Sacha, Leszek Bryniarski
Kardiol Pol 2008; 66: 873-877
- Concomitant Tombstone appearance and Lambda-like ST Segment Elevation during Hyperacute Myocardial Infarction: an explosive association
Raimundo Barbosa-Barros, Andrés Ricardo Pérez-Riera & Frank Yanowitz