| BackgroundVentricular rate completely depend on ventricular pacing in complete atrioventricular block.The high proportion of long-term ventricular pacing will leads to ventricular dyssynchrony,similar to left bundle branch block,which has adverse effects on cardiac structure and function,and increases the incidence of atrial fibrillation,heart failure,even increases mortality.In the past 20 years,right ventricular apical pacing has been regarded as the classic pacemaker of the ventricle.Related negative reports are gradually being taken seriously.The domestic and foreign scholars put forward to change the position of the ventricular electrode implantation to avoid the effect of long-term high percentage of ventricular pacing on cardiac function,such as septal pacing and his bundle pacing.However,due to the advantages of easy to operate and to fix in the right ventricular apex,it has been used as a conventional ventricular pacing for decades.Therefore,right ventricular apex pacing still occupy a certain proportion in the clinic,but the long-term effects of high proportion of right ventricular apex pacing on cardiac function should be attached great importance.However,little is known about whether the drug can improve the prognosis of patients with long-term high proportion of right ventricular apical pacing.Metoprolol,as selective beta 1 receptor blockers,delay myocardial remodeling,improve heart function and reduce the incidence of adverse cardiac events by inhibiting renin angiotensin aldosterone system(RASS).ObjectivesThis paper aims at the analysis of the efficacy of metoprolol on cardiac function,atrial fibrillation burden and QT dispersion in patients with complete atrioventricular block after the therapy of DDD pacemaker.Methods1.Subject investigated:From Sep.2013 to Mar.2016,we retrospectively enrolled 127 consecutive patients with third degree atrioventricular block after the therapy of DDD pacemaker.According to whether the patients apply metoprolol(47.5mg,AstraZeneca,J20100098)or not,patients were divided into the observation group(n=53)and the control group(n=74).2.Collection of basic clinical data:Data were recorded as baseline data in two groups of patients with DDD pacemaker after 1 week of operation.Baseline data:(1)take notes of pacemaker related parameters in the two groups,including battery,electrode impedance,atrial sensing thresholds,ventricular pacing percentage ratio,atrial high rate episodes.(2)age,gender,echocardiographic parameters(left atrial diameter,left ventricular end diastolic diameter,left ventricular ejection fraction),the heart rate level,QT dispersion,related complications,laboratory indexes(serum Pro-BNP)etc.3.Follow up and curative effect evaluation:All enrolled patients were followed up for 1 week,6 months and 1 year after the therapy of pacemaker,and the pacemaker program control,echocardiography,electrocardiogram and laboratory examination(BNP)were performed.4.Statistics analysis:All data were analyzed by Statistic Package for Social Science(SPSS,Version 20.0).Measurement data was recorded by the means of mean and standard deviation(x±s).Independent-samples T test was used as comparison between the observation group and the control group.Categorical data was recorded as frequency(rate).Comparison of categorical data was analyzed by Chi-square test.Difference is deemed to be statistical significance when p value is below 0.5.Results1.Comparison of general clinical dataData were recorded as baseline data in two groups of patients with DDD pacemaker after 1 weeks of operation.Compared with the control group,the patients with dyslipidemia were higher than those in the observation group(55.4%vs 35.8%,p<0.05).2.Comparison of follow-up parameters of 6 months postoperativelyIn the observation group and the control group,two groups were compared with the respective baseline group,atrial fibrillation burden increased(p<0.05).The ventricular rate of the control group was increased,while the heart rate was decreased in the observation group(p<0.05).3.Comparison of follow-up parameters of 12 months postoperatively?Compared with respective baseline group,left ventricular end diastolic volume(LVEDD),atrial fibrillation load increased and ventricular rate reduced in the observation group(P<0.05);while in the control group,left atrial diameter(LAD),left ventricular end diastolic diameter(LVEDD),BNP,AF load,heart rate and QTd increased(P<0.05);?Left ventricular ejection fraction(LVEF)of the two groups had no significant difference compared with respective baseline group(p>0.05)?Compared with observation group,the variation of left atrial diameter,left ventricular end diastolic diameter,atrial fibrillation burden,ventricular rate and QT dispersion in the control group was obvious(p<0.05).?The variation of LVEF between the observation group and control group had no significant difference(p>0.05).5.Comparison of the incidence of adverse events in the two groupsThe incidence of cardiac dysfunction and ventricular tachycardia in the observation group was lower than that in the control group(p<0.05).There was no significant difference between the two groups in the incidence of hypotension and dyspnea(p>0.05).ConclusionIn this study,we draw the following conclusions:1.Long term high proportion(at least 1 year)right ventricular apex pacing can cause left atrial and ventricular dilatation and increase the load of atrial fibrillation and the dispersion of QT interval.2.Metoprolol can improve the patients clinical status,delay left atrial and ventricular dilatation,partially offset the adverse influence by the high proportion of long-term right ventricular apical pacing and reduce atrial tachyarrhythmia and QT dispersion etc.3.Left ventricular ejection fraction between the two groups was no significant difference,which may be related to the short duration of pacemaker therapy so that it had no significant effect on ejection fraction.4.Metoprolol can improve long-term prognosis in patients with long-term high proportion of right ventricular apical pacing,and does not increase the incidence of adverse events. |
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