Key result
In patients presenting with outflow tract ventricular tachycardia and normal echocardiography, baseline ECG abnormalities including fascicular or bundle branch block, fragmented QRS, and low QRS voltage were significantly more common in those with underlying cardiac sarcoidosis compared to idiopathic VT.
Why the study?
A subset of patients with outflow tract VT and normal echocardiograms are later diagnosed with cardiac sarcoidosis rather than idiopathic VT, raising the question of whether sinus rhythm ECG abnormalities can differentiate the two.
Do sinus rhythm ECG abnormalities (FB/BBB, fQRS, low QRS voltage) identify underlying cardiac sarcoidosis in patients presenting with outflow tract ventricular tachycardia and normal echocardiograms?
Case-Control (n=42)
Blinded observers
No
Do sinus rhythm ECG abnormalities (FB/BBB, fQRS, low QRS voltage) identify underlying cardiac sarcoidosis in patients presenting with outflow tract ventricular tachycardia and normal echocardiograms?
In patients presenting with apparent idiopathic outflow tract ventricular tachycardia, simple sinus rhythm ECG abnormalities (conduction blocks, fragmented QRS, low voltage) can effectively identify those with underlying occult cardiac sarcoidosis.
Answers are grounded in this paper and cite their sources.
ECG abnormalities may warrant sarcoidosis evaluation in OT-VT; hypothesis-generating and should not yet change practice.
BACKGROUND: Patients with outflow tract ventricular tachycardia (OTVT) with normal echocardiogram are labeled as idiopathic VT (IVT). However, a subset of these patients is subsequently diagnosed with underlying cardiac sarcoidosis (CS). OBJECTIVE: Whether electrocardiogram (ECG) abnormalities in sinus rhythm (SR) can differentiate underlying CS from IVT. METHODS: FDG PET-CT for screening of CS. Twenty-two patients had significant abnormalities in cardiac imaging and subsequently had biopsy-proven CS (Cases). Twenty patients had normal imaging and were categorized as IVT (Controls). SR-ECGs of all patients were analyzed by 2 independent, blinded observers. RESULTS: Baseline characteristics were comparable. Among the ECG features analyzed - fascicular (FB) or bundle branch block (BBB) was seen in 9/22 Cases vs. 1/20 controls (p = 0.01). Among patients without FB or BBB, fragmented QRS (fQRS) was present in 9/13 cases but in none of the controls (p < 0.001). Low voltage QRS was more often seen among cases as compared to controls (10/22 vs. 3/20 p = 0.03). A stepwise algorithm based on these 3 sets of ECG findings helped to diagnose CS among patients presenting with OTVT/PVC with sensitivity of 91%, specificity of 75%, a PPV of 80%, and a NPV of 88%. CONCLUSIONS: In patients presenting with OTVT/PVC: FB/BBB, fQRS, and low QRS voltage on the baseline ECG were more often observed among patients with underlying CS as compared to true IVT. These findings may help to distinguish underlying CS among Cases presenting with OTVT/PVC.
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Bera et al. (2020) conducted a case-control in Outflow tract ventricular tachycardia (OTVT) with normal echocardiography (n=42). Underlying cardiac sarcoidosis vs. Idiopathic ventricular tachycardia (IVT) was evaluated on Presence of fascicular block (FB) or bundle branch block (BBB) on sinus rhythm ECG (p=0.01). In patients presenting with outflow tract ventricular tachycardia and normal echocardiography, baseline ECG abnormalities including fascicular or bundle branch block, fragmented QRS, and low QRS voltage were significantly more common in those with underlying cardiac sarcoidosis compared to idiopathic VT.
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