The tracings stored in the devices’ memories must be verified. This episode was erroneously labeled by the pacemaker as a rapid ventricular event. Analysis of the EGM suggests that it was a sinus tachycardia in this patient with a long PR interval. This tracing was obtained during effort. The P wave was not sensed as it fell inside the post-ventricular atrial blanking period.
The MVP mode confers a sizable benefit, mainly in patients in sinus rhythm, by markedly decreasing the percentage of ventricular pacing. Its indication is less clear in patients with a long PR interval, particularly if it does not shorten with exercise. It is possible that the exercise-induced dyspnea was entirely or in part due to this prolonged PR interval during effort, from a mechanism similar to the pacemaker syndrome, as a result of simultaneous contraction of the atria and ventricles.
Programming to the DDD mode is probably more appropriate for this patient. One could verify the merit of this programming change by comparing the symptoms experienced by this patient during exercise tests performed in MVP and in DDD modes.