Intolerance to physiologic pacing following upgrade of long term ventricular pacing: A drawback of routine upgrade

Background: Upgrade from VVI(R) to physiologic pacing offers benefit to patients with pacemaker syndrome (PMS). However, in asymptomatic patients with long term ventricular pacing little is known regarding potential early hazards related to the acute changes in hemodynamics following upgrade.Methods: Data of 28 patients who underwent upgrade of VVI(R) pacing were retrospectively analyzed. Mean time of ventricular pacing to upgrade was 6.3 ± 2.7 years. Indications of upgrade included PMS (considered as necessary indication) in 9 patients, and unnecessary indications in 19 patients. Pacing was upgraded to DDD in 26 patients, VDD in 1 patient, and multisite pacing in 1 patient. Three-month follow up data were reviewed. Intolerance to upgrade was defined as worsening of (or new onset) symptoms, hospital admissions or deaths following uncomplicated upgrade procedures.Results: Eleven patients (39.3%) were intolerant to upgrade. Intolerance to upgrade included palpitations/dyspnea in 3 patients, hospitalization and death in 8 patients (1 patient with pulmonary congestion related to underlying mitral stenosis and 6 patients with newly diagnosed myocardial ischemia were hospitalized; two of whom died from acute ischemia, and 1 patient had out of hospital sudden death). Patients with intolerance to upgrade were older than other patients (p < 0.001), with more frequent unnecessary upgrades (p = 0.049), more rise in HR (p < 0.001), and more preexisting undiagnosed myocardial ischemia (p = 0.001). Univariate logistic regression analysis showed that age (p = 0.009) and HR increase (p = 0.004) were significant predictors for intolerance to upgrade.Conclusions: Unnecessary pacing upgrade may not be tolerated. Pacing upgrade is recommended to be individualized for selected patients