The Value Of Cryoablation Curve In The Predicting Acute Pulmonary Vein Isolation Using The Second Cryoballoon Catheter Ablation For Treating Patients With Atrial Fibrillation

Atrial fibrillation(AF)is the most common arrhythmia in clinical practice.AF can cause thrombosis,heart failure,reducing quality of life and leading to death.As a new technique for the treatment of atrial fibrillation,cryoballoon ablation has been widely used in clinical practice because of its low pain,easy operation,short operation time,high success rate and safety.The large-scale meta-analysis showed that the efficacy and safety of cryoablation were equivalent to radio frequency ablation.No matter radiofrequency or cryoablation,intraoperative acute pulmonary vein isolation(PVI)is the key to success for AF ablation.The indicators of predicting acute PVI during operation have been the focus of current research,which can provide the basis for guiding cryoablation.Cryoablation curves directly reflect the effectiveness of cryoablation and is closely related to pulmonary vein isolation.There were no reports about thawing rate closely related with the time and temperature can evaluate PVI.ROC curve prove that thawing rate be used to further evaluate PVI.At the same time,our AF center tried to extract the freezing rate,nadir temperature,arriving plateau point time,arriving plateau point temperature and other indicators which have predictive value for pulmonary vein isolation by cryoablation curve,so as to further evaluate the acute PVI.The independent predictors were screened by logistic regression,and the logistic regression model composed of these indicators was used to further evaluate acute pulmonary vein isolation.Previous studies have found that the anatomical structure of pulmonary vein affects acute PVI,so whether the freezing and thawing rate is related to the diameter of pulmonary vein will be further explored in this study.Firstly,in order to explore the predictive value of rewarming rate in acute pulmonary vein isolation,we studied the thawing rate in cryoablation curve,and tried to explain the relationship between thawing rate and vagus reflex during cryoablation.Secondly,objective to explore the best cut-off point and predictive value of these indexes for acute pulmonary vein isolation,each predictive index extracted from ablation curve.Thirdly,the independent predictive factors of PVI were screen out by Logistic regression analysis.In addition,we create a Logistic regression model in which go deep analyzing and predicting the PVI.In the fourth part,analysis of the relationship between the freezing or thawing rate and diameter of PV.Part One The value of the thawing rate with cryoballoon catheter ab- lation in the predicting pulmonary vein isolationObjective:The PVI is one of the keys to successful ablation,the complete and effective predictors of PVI is still inadequate.We can record thawing rate which was created by cryoablation curve during the operation and used to evaluate the PVI.Methods: From January 2017 to June 2018,the patients with atrial fibrillation who were selected from hospital accepted cryoablation.A total of592 cryoapplications in 151 patients with atrial fibrillation underwent PVI using the single big(28mm)second-generation cryoballoon technique.The cryoballoon ablation rate was continuously recorded.After each cryoapplication,an achieve catheter was placed into the target pulmonary vein(PV)to determine whether PVI was present.Only the first cryoapplication at each PV was analyzed to avoid cumulative effects.Every time we perform cryoablation,we document it in cryoablation curve form.Through thawing curve of cryoablation curve,the each thawing rate was calculated.Then by ROC curve we could evaluate the value of thawing rate as predictor of PVI to cryoballoon catheter ablation.Results: In the process of cryoablation of pulmonary vein potential(left upper,left lower,right upper and right lower pulmonary vein),the thawing rate of acute pulmonary vein isolation ablation was slower than that of cryoablation without acute pulmonary vein isolation(P < 0.05).Area under the ROC curve was 0.736 for interval from start until-10?,0.754 for interval from start until-5?,0.733 for interval from start until 0?,0.709 for interval from start until 5°C,0.783 for interval from start until 10?,0.823 for interval from start until 15°C and 0.81 for interval from start until 20°C.The result indicated this thawing rate has predictive value,the value of individual interval can be different.The thawing rate from start to 15°C had been calculated when it would have the greatest potential effect prediction value,area under the ROC curve was 0.823 and Youden Index was 0.558.The best cutoff value of interval thawing rate at 15°C for PVI was?2.14°C/S and its sensitivity,specificity positive and negative predictive values was 88.62% 67.18%,77.2% and 82.5%,respectively.Thawing rate in occurrence of vagus reflex cryoapplications were rising slower than in non-occurrence(1.77±0.47°C/S VS 2.22±1.01°C/S,P<0.01).Predictive value of thawing rate for vagus reflex also has prediction results which were far from ideal and 0.64 AUC.Summary:1.The ROC curve result indicated thawing rate has prediction value for PVI and has the certain practical value.The AUC of the thawing rate is above0.7,it could have predictive value of PVI.2.The paper found that the thawing rate has different predictive value according to the different interval of thawing curve.The interval of thawing rate at 15 °C was not only the higher predictive value in all intervals,but also one of the largest and most value.3.The best cutoff value of interval thawing rate at 15°C for PVI was?2.14°C/S and has higher sensitivity,its sensitivity was improved up to88.62%.4.Compared with the cryoablation without vagus reflex during the operation,the thawing rate in the ablation with vagus reflex is slower,which also has a certain predictive value for the occurrence of vagus reflex.Part Two The predictive values and cut-off points of each predictor for PVI on cryoablation ablation curveObjective:Through the application of the freezing curve model in the first part,the prediction indexes are obtained.The best cut-off,sensitivity,specificity and AUC value of each predictor for acute pulmonary vein isolation were analyzed by ROC curve.Methods:All of 151 AF patients performing from January 2017 to June2018 cryoballoon catheter ablation were enrolled.In the process of cryoablation,the freezing temperature of each time point in the freezing curve was recorded by Medtronic cryoablation system software and reconstructed to the computer.We reconstructed the curve through computer.According to characteristic rate,the relative cryoablation curves had been divided into three phases: fast falling phase,plateau phase and thawing phase.And through cryoablation curves the predictors were obtained.We got freezing rate,nadir temperature,arriving plateau point time,arriving plateau point temperature,achieving-40? within 60 s,thawing rate and other indexes through curve,and all these factors through this research had predictive value for PVI.Draw the ROC curve of each curves,we get the cut-off value,AUC,sensitivity,specificity and Youden Index for predictive indicators.Results: The optimal cut-off point of freezing speed was ?-1.237,AUC was 0.764,Youden index was 0.414,with 66.56% sensitivity and74.81% specificity.The best cutoff value of interval thawing rate at 15°C for PVI was ?2.14°C/S and its AUC,Youden Index,sensitivity and specificity was 0.823,0.558,88.62% and 67.18%,respectively.The best cutoff value of arriving plateau point time for PVI was >49s,its AUC,sensitivity and specificity was 0.763,82.86% and 56.76%,respectively.The best cutoff value of arriving plateau point temperature was?-37?,its AUC,sensitivity and specificity was 0.778,76.6% and 69.73%,respectively.Nadir temperature cutoff value at ?-43°C exhibited 80.98% sensitivity and 65.79% specificity.Achieving-40? within 60 s and vagus reflex were predictors for PVI and AUC was 0.671 and 0.532 respectively.Each predictor cut-off value provided us very valuable theoretical evidences for researching PVI.Summary:1.Some indexes in the freezing curve also have predictive value for acute pulmonary vein isolation,including freezing rate,nadir temperature,arriving plateau point time,arriving plateau point temperature and thawing rate.All these indexes have high predictive value for pulmonary vein isolation.2.The cut-off point of freezing rate,arriving plateau point time and thawing rate were high sensitivity up to 80%,those predictors provide objective evidences for option of PVI.3.The achieving-40? within 60 s and vagal reflex has lower prediction value for PVI.Part Three The independent predictors of pulmonary vein isolation were screened and logistic regression model was established to analyze acute pulmonary vein isolationObjective: Logistic regression analysis was used to screen out independent predictors of acute pulmonary vein isolation,and logistic regression model was established by these independent predictors to further predict acute pulmonary vein isolation..Methods: We got freezing rate,nadir temperature,arriving plateau point time,arriving plateau point temperature,achieving-40? within 60 s,thawing rate and other indexes through curve.Univariate analysis of logistic regression was used for the above indexes,and multivariate analysis of logistic regression was used for the indexes with statistical significance(P < 0.05)..With adopting the Logistic approach,the effective and independent factors are selected.With combining the factors,the Logistic model are formed and studied to acute PVI.Results: The each predictor was recorded by real time during operation and curve.At the same time,based on the current research status and recorded curve,freezing rate,nadir temperature,arriving plateau point time,arriving plateau point temperature,achieving-40? within 60 s,thawing rate and vagus reflex were predictors for PVI.Finally,the conclusion is derived through Logistic regression analysis: freezing rate,thawing rate and nadir temperature were independent predictors(P<0.05).The predictive model for acute PVI combined with nadir temperature,freezing and thawing rate,which had 0.843 AUC,the best cut-off>0.457 and up to 89.85% sensitivity.Summary:1.Logistic regression analysis showed that freezing rate,thawing rate and nadir temperature of cryoablation were independent predictors of acute pulmonary vein isolation.2.The nadir temperature,freezing and thawing rate building Logistic formulas that have the greatest prediction value to the PVI.Part Four The analysis of correlation of freezing and thawing rate with diameter of PVObjective: The correlation analysis of freezing or thawing rate and the diameter of PVI.Methods: The diameter of PV were measured through CTA,freezing and thawing rate were calculated through the cryoablation of curves.Person correlation analysis was used to analysis the correlation of rate and diameter of PV.Results:The correlation coefficients between freezing rate and the diameters of LSPV,LIPV,RSPV and RIPV were-0.637,-0.79,-0.74 and-0.81,respectively(P < 0.05);.Thawing rate was significantly correlated with diameter of LSPV,LIPV,RSPV and RIPV,the correlation coefficients were-0.326,-0.31,-0.377 and-0.48,respectively.Summary: There was negative correlation between the freezing rate and diameter of PV,diameter of PV was larger and the cooling-rate was faster in the freezing process.The speed of thawing are related with the PV of diameter is negative,it shows that the slower the thawing speed is,the larger of PV diameter is.Conclusions:1.The thawing rate has predictive value for PVI.We use the ROC to get maximum value for PVI in the interval from start until 15?.Thawing rate in occurrence of vagus reflex cryoapplications was rising slower rate and there was function of predicting on vagus reflex.2.We can use the cryoablation curve in cryoballoon catheter ablation to produce thawing rate,freezing rate,nadir temperature arriving plateau time,arriving plateau temperature and other major predictors.Each indicator has best cut-off value and could better assess the prediction to PVI.3.The conclusion is derived through Logistic regression analysis:freezing rate,thawing rate and nadir temperature were independent predictors.The nadir temperature,freezing and thawing rate building Logistic formulas that have the greatest prediction value to the PVI.4.Freezing and thawing rate was closely related to the diameter of PV.