This 31 yo who is otherwise healthy had sudden syncope while riding a bike. He remembers looking down, then becoming dizzy, then waking up on the ground with his feet still attached to the pedals. He thought he was unconscious by himself for 45 minutes (!). Then he awoke and called 911. He had no prodromal vasovagal symptoms such as flushing, nausea, or diaphoresis.
He had a several year history of palpitations without syncope, but had one presyncopal epsisode one month prior. He had been seen by a local cardiologist 3 years prior and had what is described in records as a normal ECG and normal Echo, and had been encouraged to resume exercise.
Here is his presenting ECG in the ED:
|Sinus rhythm with some artifact. QTc may be slightly prolonged; I eyeball it at about 470ms. This is not long enough to be dangerous.|
His symptoms are very alarming. There are 2 features which are high risk: no prodrome other than dizziness, and onset with exertion. When a young person who is otherwise healthy presents with high risk syncope, a normal exam, and NSR, it is essential to obtain an ECG not only to look for ischemia, blocks such as LBBB and RBBB, but also for inherited disorders that cause dysrhythmia. There are 5 that I think of: WPW, HOCM, Brugada, long QT, and Arrhythmogenic Right Ventricular Dysplasia (ARVD), which is a disorder of fatty infiltration of the RV that causes sometimes lethal ventricular tachycardia originating from the RV. ARVD is quite rare, not often thought of, and very difficult to recognize on the ECG.
Alas, this young man's presenting ECG shows none of these.
Surprisingly, the first troponin returned at 3.44 ng/ml, the second at 7.48. Clinicians thought they were dealing with a dysrhythmia due to ACS/NSTEMI, and started heparin and aspirin. He was admitted to the hospital.
An echo revealed segmental hypokinesis of the apex of the right ventricle only. The contour at this portion of the RV free wall was also unusual, and raised suspicion for ARVD.
MRI of the heart was done; here is the final report:
There is focal dyskinesia involving the RV apex and the anterior wall. On the T2-weighted sequence, there is linear increased signal in the RV myocardium suggesting fatty infiltration. There is no definite delayed enhancement in this area. These findings are suspicious for arrhythmogenic right ventricular dysplasia.
Coronary cath was normal. Troponins trended down.
Here is another ECG from 3 days later:
Now there is abnormal T-wave inversion in III, aVF, and V2. So the patient only has minor criteria by ECG, and only on the followup ECG (see below).
He had an EP study that induced VT at a rate of 252. Here is the induced VT:
|VT at a rate of 252 bpm. Short QRS for VT (116 ms). Not a typical LBBB morphology, but induced VT in ARVD need not be of LBBB morphology.|
A heart rate like this would stress the heart and lead to troponin release.
An implantable cardioverter defibrillator was placed.
ARVD, also known as arrhythmogenic RV cardiomyopathy, is estimated to have a prevalence of 1 in 5000 adults and is responsible for approximately 11% of sudden death in young adults and 22% in a study of athletes in northern Italy. The diagnosis is not easy (see below).
Gemayel C, Pelliccia A, Thompson PD. Arrhythmogenic right ventricular cardiomyopathy. J Am Coll Cardiol. 2001;38(7):1773. Full text: http://content.onlinejacc.org/cgi/reprint/38/7/1773.pdf
There is a 2010 publication by the Task Force in Diagnosis of ARVD: Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the task force criteria.
Free full text: http://circ.ahajournals.org/content/121/13/1533.full.
There are 6 categories of criteria:
3) ECG Repolarization
4) ECG Depolarization
6) Family History.
ECG and historical Highlights of this publication are (Suspect ARVD with):
1) High risk syncope with no other etiology; Family History
2) Depolarization abnormalities (Major criteria):
a) Epsilon Waves
b) Localized prolongation (greater than 110 ms) of the QRS complex in right precordial leads (V1-V3)
3) Repolarization abnormalities in patients of age at least 14 years (because younger patients often have juvenile T-waves)
a) Minor: Inverted T-waves in right precordial leads V1-V2
b) Major: Inverted T-waves in right precordial leads V1-V3 or beyond (major criteria)
a) Major criterion:
i) VT of LBBB morphology with superior axis (negative or indeterminate QRS in leads II, III, aVF and positive in lead aVL) (major criteria)
b) Minor criteria:
i) VT of LBBB morphology with inferior axis (positive QRS in leads II, III, aVF and negative in lead aVL) (minor criteria)
ii) More than 500 PVCs per hour
5) Finally, it is a progressive disease and patients without ECG abnormalities may develop them over time.
Here is another nice example. I've taken the liberty of blowing up part of the ECG at this link for better viewing. Look closely at V1-V2: