By Dr.Leen Alblaihed & Dr. Ali Farzad
A 65-year-old male presents to the ED with diarrhea and generalized fatigue, and weakness. The following ECG was obtained. What is the diagnosis?
a) Wellens’ syndrome (anteroseptal ischemia)
c) Hypertrophic obstructive cardiomyopathy (HOCM)
d) Elevated intracranial pressure
Answer: b) Hypokalemia
This ECG is abnormal and has a markedly prolonged QT-interval. There are large T-waves that are biphasic in the anterior leads (initially down-going then up) and suggestive of the presence of a T wave-U wave fusion complex & severe electrolyte abnormalities. Hypokalemia, hypocalcemia, and hypomagnesemia all can cause QT-prolongation and T-wave abnormalities.
This patient was initially thought to have Wellens’ waves because of the biphasic T-waves in V1- V3. However, he was found to have severe hypokalemia (K+ of 2.3 mEq/ L (normal = 3.5 – 5.3 mEq/L)). Biphasic Wellens’ waves have an initially upright morphology and are suggestive of subacute anterior ischemia, usually caused by critical proximal left anterior descending (LAD) coronary artery occlusion (Figure 1). Conversely, severe electrolyte abnormalities may cause biphasic T-waves that mimic Wellens’ waves but are initially down-going (inverted T) then up-going (U-wave) as was seen in this patient.
This ECG does not have features suggestive of HOCM, such as high voltage or deep and narrow Q-waves in the inferior and lateral leads. Also, there is an absence of large widespread deeply inverted T-waves (cerebral T-waves) seen in patients with elevated intracranial pressure (ICP) (Figure 2), which should be considered in patients with decreased level of consciousness and these ECG findings.
Figure 1 – Type 2 Wellens’ waves: biphasic T-waves in mid-precordial leads have a terminal T-wave inversion and go up first, then down. (Reprinted from ECG Weekly – https://ecgweekly.com/2015/09/amal-mattus-ecg-case-of-the-week-september-21-2015/)
Figure 2 – Cerebral T-waves – Note the prolonged QT and deeply inverted T-waves. (Reprinted from ECG Weekly – https://ecgweekly.com/2015/05/amal-mattus-ecg-case-of-the-week-may-11-2015)
Take Home Points:
• Wellens’ waves are deeply inverted T-waves or biphasic T-waves in mid-precordial leads, and highly specific for critical obstruction of the proximal LAD. The biphasic T-waves in Wellens’ syndrome have a terminal T-wave inversion and go up first, then down.
• Severe hypokalemia may cause U-waves, which might fuse with T-waves to create a T-wave/U-wave complex that may mimic Wellens’ waves. These complexes can be distinguished from Wellens’ waves by their morphology, as they go down first, then up.
• Remember that Wellens’ is a syndrome and not just an ECG finding. There are certain conditions and normal variants in patients with high voltage ECG’s that may mimic Wellens’ waves.