Optimized Pacing Therapy With β-blockers For Atrioventricular Block Patients With DDD Pacemaker

Objective To investigate the impact of long-term right ventricular apical pacing on cardiac remolding and function in the patients DDD pacemaker being implanted for atrioventricular block, explore the effect and significance of β-blocker to control the higher sinus heart rate of the patients with a high dependence of right ventricular pacing and thereby to reduce the surplus right ventricular pacing.Methods Patients with atrioventricular block and DDD pacemaker being implant-ed with a higher ventricular pacing rate over80percent were selected in this study. In beginning of the study, both of the rest heart rate and mean heart rate tested by ECG and HOLTER were over or equal to70bpm, and the heart rate distribution histogram collected from the pacemaker by the pacemaker programmer was mainly located in the high rate histograms of over or equal to70bpm, and therefore the DDD pacemak-ers mainly worked in atrial sensing and ventricular pacing mode (VAT mode). The patients were guided to take β-blocker (metoprolol extended release tablet) with appropriate dosage and were followed-up. In the following-up, the resting heart rate, mean heart rate, percentage of heart rate distribution, atrial and ventricular pacing proportion, SF-36quality of life survey scores were tested before and after the mediation being tasken.Simultaneously,we had analyzed the cardiac echocardiograph-ic parameters of patients who had implanted pacemakers for more than3years.Results (1) A total of39patients were enrolled in this study,33cases completed the follow-up, while6cases were lost, there were20cases of patients who had implanted pacemakers for more than3years;(2) For the20patients who had implanted pacemakers for more than3years, the echocardiographic parameters including LAD, LVDd and LVMI were all increased compared to the time the pacemakers were implanted (38.85±4.90mm vs40.95±4.08mm;47.65±6.41mm vs51.4±5.68mm;114.92±21.17g/m2vs115.67±6.13g/m2,P<0.05), the same goes to the decrease in LVEF, the differences were significant (69.75±1.69%vs62.61±11.14%, P<0.05), but not in IVST and LVPWT (11.95±1.15mm vs11.75±1.25mm;10.05±1.28mm vs10.40±1.39mm, P>0.05);(3) The history of cardiovascular disease was the main factor that related to the increase of LVDd (P<0.05);(4) The resting heart rate and mean heart rate were significantly decreased after the medication (76.52±7.76bpm vs67.61±3.52bpm,75.13±6.10bpm vs67.17±2.48bpm,P<0.05);the data from the heart rate histogram displayed the proportion of heart rate distribution of50～70bpm (low frequency section) and>70bpm(high frequency section)were significantly different before and after the use of p-blocks(31.00±14.44%vs50.42±14.90%;69.00%±14.44%vs49.58±14.90%,P<0.05);(5) There was no significant diffrence in the proportion of ventricular pacing before and after medication(95.18±6.03%vs95.12±6.18%,P>0.05), but atrial pacing proportion was increased after the medication (5.97±4.89%vs11.49±8.33%,P<0.05), After the treatment, the SF-36quality of life scores of33patients were increased, but had no significant difference(100.64±9.46vs103.51±8.39, P>0.05);(6) Four cases of paroxysmal atrial fibrillation (PAF) were detected in this study, two cases of intermittent atrial myoelectricity(EMG) mistaken-sensing, one case of intermittent ventricular EMG mistaken-sensing, one case of intermittent atrial low-sensing. Pacemaker sensing abnormalities were being eliminated after programmable examination.Conclutions (1) Long-term right ventricular pacing can lead to the increase of left atrial and left ventricular dilatation,the reduction of LVEF;(2) The pacing optimization is still needed for Atrioventricular block patients with high ventricular pacing dependence after DDD implantation;(3) β-blockers can control the sinus heart rate of the ventricular pacing dependence patients,thereby reducing excessive ventricular pacing,thus contribute to the optimization of pacing stratey and prevention of cardiovascular risk;(4) β-blockers can significantly reduce excessive ventricular pacing,reduce the energy consumption of pacemaker and prolong the life of the battery;(5) Both Holter and pacemaker programmable detection plays an important role in the management of pacemaker.