Influence Of The Stimulus To R Peak Time In Lead V5 On Cardiac Structure And Function In Pacemaker-dependent Patients

Objective: To observe the influence of the stimulus to R peak time in lead V5 on cardiac function and structure in pacemaker-dependent patients.Methods: 89 patients with third-degree atrioventricular block receiving right ventricular pacing from January 2010 to May 2020 in our hospital were included.All patients underwent electrocardiogram and transthoracic echocardiography.cut-off point of 97.5 ms for the decrease in ejection fraction due to the stimulus to R peak time in lead V5 was obtained from the ROC curve,and all patients were divided into two groups: group A(the stimulus to R peak time in lead V5<97.5ms)and group B(the stimulus to R peak time in lead V5≥97.5ms),and the preoperative and follow-up echocardiography and general clinical characteristics of the two groups were compared.Using the occurrence of decreased ejection fraction during the follow-up period as the end point,all patients were divided into the group with no decrease in ejection fraction(group 1)and the group with decreased ejection fraction(group 2),and the stimulus to R peak time in lead V5 was compared between the two groups.Data analysis was performed with SPSS 26.0 statistical software.Results: During a mean follow-up of(38.07±31.47)months,a total of14 patients developed decreased ejection fraction,including 7 in group A(Total number of Group A: 67)and 7 in group B(Total number of Group B:22).The incidence of decreased ejection fraction was significantly higher in group B compared to group A(31.8% vs 10.4%,p=0.017),and the Left ventricular end diastolic diameter was significantly larger in group B compared to group A at follow-up(52.95±9.01 vs 48.39±5.95,p=0.035).The stimulus to R peak time in lead V5 is significantly longer in group 2compared to group 1(94.64±22.24 vs 81.27±20.82,p=0.032).The result of multiple logistic regression analysis showed that the stimulus to R peak time in lead V5≥97.5ms,body mass index(BMI),and increased preoperative left ventricular end-diastolic diameter were independent risk factors for decreased ejection fraction in pacemaker-dependent patients.Conclusion: Prolonged stimulus to R peak time in lead V5 can be used as a predictor of postoperative decline in cardiac function in pacemaker-dependent patients,which is more likely to occur when the stimulus to R peak time in lead V5≥97.5ms.In addition,BMI and increased preoperative left ventricular end-diastolic diameter are also independent risk factors for decline in cardiac function in pacemaker-dependent patients.