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Notes: PRECH, M., et al.: Effect of Restoration of AV Synchrony on Stroke Volume, Exercise Capacity, and Quality-of-Life: Can We Predict the Beneficial Effect of a Pacemaker Upgrade? The aim of this study was to assess to what extent patients with VVIR pacemakers and without overt symptoms of a pacemaker syndrome benefit from a pacemaker upgrade, and if a preoperative noninvasive measurement of the change in stroke volume (SV) could predict the effect of a pacemaker upgrade. The study group consisted of 20 (12 women, 8 men) VVIR patients with a mean age of 60 years. The indication for the first implantation was AV block in 13 patients and SSS in 7. The mean time of a ventricular pacing was 77 months. The objective (echocardiography, an exercise capacity) and the subjective (the quality-of-life) parameters investigated in patients during ventricular pacing were compared to results obtained 2 months and 1 year after a pacemaker upgrade. To assess preoperatively a change in a SV expected after upgrading, attempts were made to restore AV synchronization by the use of a transesophageal pacemaker. An increase in SV (from 5% to 〉 35%) during temporary AV resynchronization was observed in each patient. Values of SV increase correlated with those obtained 2 months (r = 0. 65; P 〈 0.01) and 1 year (r = 0.66; P 〈 0.01) after an upgrade. Superior hemodynamics was associated with a significant improvement of an exercise capacity in both subgroups of patients. The most significant improvement in the quality-of-life was observed in patients with SSS. We did not find correlations between SV and the quality-of-life assessed 2 months (r = 0.043; NS) or 1 year (r = 0.02; NS) after an upgrade. In conclusion, a pacemaker upgrade performed after a long-term ventricular pacing resulted almost consistently in the improvement of hemodynamics and was associated with an increase of exercise capacity. In patients with SSS it was followed by the significant improvement of their quality-of-life. Such a relation was not observed in patients with AV block as some of them (especially those with VVIR pacemakers) felt quite well during ventricular pacing. The proposed preoperative echocardiographic evaluation may precisely predict the degree of hemodynamic improvement expected after a pacemaker upgrade.