The answer is C, an EP study with programmed electrical stimulation. So when doing a workup for someone who has suspicion of an inherited arrhythmia syndrome, a number of studies and tests should be performed. First, a detailed history should be performed with the patient, including syncope, palpitations, and aborted sudden cardiac death. The results of the history can help inform all of the inherited arrhythmia syndromes. Similarly, a good family history needs to be done. This should include a family history of sudden death, a family history of implanted devices, including pacemakers and defibrillators, a family history of heart failure, a family history of late-term miscarriages, and also a family history of sudden infant death syndrome. An electrocardiogram should be performed, and that may show long QT syndrome, short QT syndrome, Brugada syndrome, and evidence of arrhythmogenic right ventricular cardiomyopathy. Imaging is important because it can pick up evidence of cardiomyopathies, including hypertrophic cardiomyopathy, dilated cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy. An echocardiogram is usually performed first, but a cardiac MRI is much better looking for evidence of right ventricular abnormalities in arrhythmogenic right ventricular cardiomyopathy. Stress testing is potentially useful and will show arrhythmias in somebody with a normal baseline electrocardiogram in catecholaminergic polymorphic ventricular tachycardia and will show, as we saw in the first case, the absence of QT shortening and therefore QTC prolongation in type 1 and type 2 long QT syndrome. Thymoglogic testing can be used with intravenous procainamide or other sodium channel blockers in Brugada syndrome and with beta-adrenergic agonists in catecholaminergic polymorphic ventricular tachycardia, such as isoproterenol. Electrophysiology testing or program stimulation is not useful as a diagnostic test for the inherited arrhythmia syndromes, although it may be useful prognostically to identify who may be at higher risk of sudden death in patients with Brugada syndrome, and thus was not the correct answer in this question. Now, if one does testing on patients with unexplained cardiac arrest, the pickup rate is reasonably good. This is an example of one study done in 2009, which show a diagnosis was made in over half of patients who presented with unexplained cardiac arrest. And here you can see that in this cohort, a long QT syndrome and catecholaminergic polymorphic ventricular tachycardia and arrhythmogenic right ventricular cardiomyopathy were the most common. Now, which syndromes are the most common will vary based on the referral patterns, but also based on race, the country of origin, et cetera, as some syndromes are much more common in some places than another. For example, Brugada syndrome in Southeast Asians and arrhythmogenic right ventricular cardiomyopathy in parts of Italy.

inherited arrhythmia

electrocardiograms

Brugada syndrome

syncope

diagnosis rates