Clonidine hydrochloride may be a factor in producing a high-grade atrioventricular block. Therefore, careful follow-up with repeated ECG monitoring seems to be indicated when clonidine is given to a patient with suspected cardiac conduction disease, especially if the patient is concurrently receiving digitalis therapy.
(JAMA 238:1930-1932, 1977)
Kibler LE, Gazes PC. Effect of Clonidine on Atrioventricular Conduction. JAMA. 1977;238(18):1930-1932. doi:10.1001/jama.1977.03280190032022