An initial evaluation strategy of taking a detailed history, physical examination, risk stratification, ECG recording and BP measurement should help decide what investigations should be ordered (based on whether the syncope is cardiac related, reflex/neutrally mediated, secondary to cerebrovascular disease or due to orthostatic hypotension). The majority of patients with paroxysmal AV Block present with presyncope, syncope, with or without a prodrome or are asymptomatic.

• The pathway to conclusively diagnosing a patient with paroxysmal AV block is not straightforward.
• Since most patients present with a history of recurrent unexplained syncope and fortuitous timing would be required to document classical ECG findings during an acute episode, it would be best to treat it as a diagnosis of exclusion.
• An initial evaluation strategy of taking a detailed history, physical examination, risk stratification, ECG recording and BP measurement should help decide what investigations should be ordered (based on whether the syncope is cardiac related, reflex/neutrally mediated, secondary to cerebrovascular disease or due to orthostatic hypotension). “ESC Guidelines on Syncope (Diagnosis and Management of)”.

• History of syncope, presyncope, duration of each episode, number of episodes, activities during the syncopal episode, aggravating or relieving factors, history of past medical illnesses, prodrome/ recovery phase description in terms of signs, symptoms and duration are important points to be addressed whilst taking a history of a syncope patient.
• A study of 341 syncope patients showed that the time between the first and last syncopal episode being less than 4 years, syncope during effort or supine position, a history of palpitations, convulsions or blurring of vision were important predictors of a cardiac syncope.
• Similarly, duration of prodrome > 10 seconds history of pallor, nausea, diaphoresis, dizziness, presyncope, abdominal discomfort and time between first and last syncopal episode being more than 4 years were important predictors of a neutrally mediated syncope.^[2]
• Based on a detailed history, one can decide whether a cardiac syncope was secondary to a rhythm dysfunction, structural cause or ischemia related and would warrant a work up of an ECG, Holter monitoring, echocardiography, electrophysiologic study, or an exercise stress test. ^[2]
• Similarly, neutrally mediated syncope maybe vasovagal, situational, secondary to increased carotid sinus sensitivity or non classical and orthostatic hypotension may be due to a primary or secondary autonomic failure, secondary to drugs or hypovolemia. This may be further explored by a carotid sinus massage, tilt table testing, adenosine plasma levels or an adenosine triphosphate stimulation test.“ESC Guidelines on Syncope (Diagnosis and Management of)”.

• Important aspects of one’s history include the frequency, timing, duration, severity, longevity, circumstances, triggers (eg, urination, defecation, cough, prolonged standing, shaving, tight collars, and head turning) and alleviating factors of symptoms suspicious for bradycardia or conduction disorders.
• A thorough family history, medical history, cardiovascular history and review of symptoms should also be done. ^[1]

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