[Chronotropic incompetence: when should a pacemaker be considered? Which pacing system and which settings?].

Chronotropic incompetence is defined as the inability to increase and maintain heart rate appropriately during exercise. Intolerance to exertion is manifested by a number of clinical symptoms, and is almost obligatory if heart rate cannot be increased. Several rate-modulating pacing systems have been developed. The most obvious and reliable way to increase heart rate during exercise is to detect the sinus node. Adding an atrial lead in a patient in complete AV block and VVI pacing is the most satisfactory way to correct chronotropic incompetence in some patients. Rate-adaptive sensors include motion sensors, respiration sensors, QT interval, and right ventricular contractility. Indications for rate-adaptive pacing should be based on clinical symptoms, demonstration of a lack of cardiac acceleration during exercise, and the presence of another indication for pacing.