Pregabalin-induced first degree atrioventricular block in a young patient treated for pain from extrapulmonary tuberculosis

Abstract

Pregabalin, widely used in the treatment of several pain disorders, is usually well tolerated. Uncommonly, the drug may induce cardiac side effects, rarely prolongation of the PR interval. The latter has never been described in patients with healthy heart or normal renal function. We characterize a unique case of a young man with extrapulmonary tuberculosis and no detectable or known cardiac or kidney diseases, treated with pregabalin to control the severe pain due to the involvement of the spinal cord by the tuberculosis, showing an atrioventricular (AV) block due to pregabalin administration. The reported case emphasizes the need of monitoring PR interval during treatment with pregabalin, even in patients without background of cardiac or renal diseases.

Pregabalin and PR interval prolongation: any association?

“…The notion of pregabalinassociated PR interval prolongation and heart blocks in the literature mostly came from case reports/anecdotes. 2 Aksakal and co-workers reported on a case of complete AV block (the ventricular rate was 39 beats/minute) in a patient with uremia and pregabalin overdose; in fact, this was the first reported pregabalin-related heart block outside the clinical trials of the medication before its release and approval for medical use. 11 Their patient was taking oral pregabalin at a dose of 300 mg/d over the preceding 8 months.…”

“…In addition, the inhibitory effect on the autonomic nerve terminals in the heart may result in the modulation of the neuronal excitability. 2 The PR interval encompasses both the atrial contraction (P-wave) and the time needed for the electrical impulse to descend downwards through the AV node and the His-Purkinje fiber system to reach and activate the ventricles. An interval of 0.12 to 0.20 seconds is required normally in individuals with a resting heart rate of 60 to 100 beats/minute.…”

“…A PR interval of 0.12 to 0.20 seconds is the normal range and is not gender-related; values greater than 0.20 second imply a prolonged PR interval. 2,3 Serum levels of pregabalin were not measured. A 24-hour Holter monitoring was done in one patient only; she gave a history of recurrent pre-syncope; this investigation turned out to be unremarkable.…”

“…Scarano and colleagues found an incomplete AV conduction block in a patient with neuropathic pain who was prescribed pregabalin; the PR prolongation was minimal and the patient had ischemic heart disease and stroke. 12 Schiavo and colleagues reported on a case of extrapulmonary (lower spine and sternum) tuberculosis who was prescribed pregabalin, 150 mg/d, to alleviate severe neuropathic pain in the lower back and legs (2). He demonstrated normal kidney function and normal ECG (and cardiac function) before the start of pregabalin therapy.…”

“…PR interval prolongation has been observed by some researchers and documented through case reports, usually in patients with pre-existent heart disease and/or renal failure. 2 The cardiac conduction defects of pregabalin monotherapy have also been observed in patients with structurally normal heart and in the presence of normal kidney function. 3 The current medical literature provides sparse information about the cardiac side effects of pregabalin, in particular, heart blocks and conduction defects.…”