Comparison between patients with and without reliable ventricular escape rhythm in the presence of long standing complete atrioventricular block.

The underlying heart rhythm was evaluated in 74 patients with complete atrioventricular block and had a permanent pacemaker implantation. The pacing was inhibited for 10 seconds or until the patient developed symptoms of presyncope or syncope. Fifty-six patients (74%) had a reliable escape with a mean cycle length of 2010 +/- 596 msec and a mean escape interval of 2335 +/- 971 msec. In 93% of these patients the escape interval was < 4 seconds. The patients without reliable escape (24%), developed symptoms only after a mean of 7153 +/- 1875 msec. The duration of the conduction disorder was longer in the patients without escape and the intraventricular conduction was slower. More patients without escape were treated and antiarrhythmic agents. Forty-eight patients were followed for 1 year and underwent at least two different studies and 13% had different results at different tests. In conclusion, patients without reliable escape have a longer history of conduction disorder, a slower intraventricular conduction, and are frequently treated with antiarrhythmic agents. Even patients with reliable escape occasionally may show a greater pacemaker dependence; therefore, they should also be considered as pacemaker dependent.