Wide QRS Complex Tachycardia in an Apparently Healthy Man
A previously healthy man in his 40s presented with sudden onset palpitation that had been going on for more than an hour, with a heart rate of 224 beats per minute.

A 12-lead electrocardiogram (ECG) demonstrated a fast regular wide QRS complex tachycardia. Repeated ECG
showed sinus rhythm with right bundle branch block and left anterior fascicular block.
In this patient, there were ECG features that strongly suggested VT, including marked right-axis deviation, negative QRS concordance in leads V1 through V5, an R-to-S interval greater than 100 milliseconds in a precordial lead (V6), and aQ-wave duration greater than 40milliseconds in aVR.

The differential diagnosis for this new-onset, sustained, stable VT in a middle-aged, apparently healthy man includes hypertrophic cardiomyopathy, cardiac malignancy, and infiltrative diseases, such as cardiac amyloidosis, hemochromatosis, and cardiac sarcoidosis (CS).

Cardiac magnetic resonance imaging showed mild left ventricular systolic dysfunction (quantitative left ventricular ejection fraction of 45%) and severe thickening of the basal and mid-anterior wall, basal to mid-intraventricular septum, and the basal right ventricular free wall. Biopsy of this lymph node revealed noncaseating granulomas. The clinical presentation, imaging studies, and lymph node histology were all consistent with the diagnosis of CS. Given the bifascicular block and sustained VT, the patient underwent implantation of a pacemaker/implantable cardioverter-defibrillator (ICD). He was prescribed high-dose corticosteroids and discharged home with close follow-up.

Source: https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2758794