Limitations of the long-term clinical application of rate hysteresis

Rate hysteresis is the ability of a pacemaker to pace at an automatic rate that is different from the escape rate. We reviewed our experience with this programmable feature and its utility. The long-term clinical application of rate hysteresis was limited due to the development of atrial fibrillation or to slowing of the intrinsic cardiac rhythm in 27.6% of the 29 patients. Since many patients with sick sinus syndrome have preserved AV conduction, one might expect that these patients would have an adequate intrinsic heart rate to allow successful use of rate hysteresis pacing mode. Sick sinus syndrome was the intrinsic rhythm disturbance in 63% of the group requiring discontinuation of rate hysteresis. These patients may represent a subgroup in whom any theoretical advantages provided by the rate hysteresis feature may be outweighed by the propensity for the development of atrial fibrillation or significant slowing of the intrinsic rhythm.