¹⁸F-FDG PET Cardiac Function Assessment In Predicting Ventricular Arrhythmia Events In Patients With Implantable Cardioverter-defibrillator Implantation

Background.Ventricular arrhythmia(VA)is one of the major causes of sudden cardiac death(SCD)for patients.Accurate prediction and early detection of risk of VA is one of the important strategies to prevent SCD.Left ventricular ejection fraction(LVEF)as the primary approach to identify patients with high risk of sudden cardiac death(SCD)has poor predictive value for VA.Ventricular complicated or abnormal anatomical structure,myocardial lesions or scars and other factors provide the trigger and maintenance substrate for VA,which lead cardiac dysfunction.18F-fluorodeoxyglucose positron emission tomography(18F-FDG PET)has unique advantages in evaluating Global and regional cardiac dysfunction.This prospective study sought to investigate the imaging characteristics of VA patients to predicting VA for patients with implantable cardioverter defibrillator(ICD)and the possibility of predicting the occurrence of VA based on 18F-FDG PET,which provide new technical ideas for effective prevention and treatment of VA.Methods.We performed a prospective observational study and recruited patients who required ICD placement.Pre-procedure image scans were performed.The global and regional cardiac function parameters,left ventricular dyssynchrony parameters,scar burden was analyzed by Single-Photon Emission Computed Tomography(SPECT)/18F-FDG PET.For each patient assessment,a standard 17-segment of the left ventricle proposed by the American Heart Association was applied.Follow-up visits were scheduled every 6-12 months,or more often when clinically indicated.Occurrence of ventricular tachycardia(VT)and ventricular fibrillation(VF)was established through routine ICD interrogations and review of electronic medical records.Associations between quantitative parameters of imaging and VA were analyzed.Results.In 51 patients(33 males,53.9 ± 17.2 years)with mean follow-up of 12.2 ± 6.4 months(range 1 month-2 years),17(33.3%)patients developed VA.There were 57 VTs(39 received antitachycardia pacing therapy and 15 received shock)and five VFs(all received therapy and shock).Compared with patients without VA,patients with VA had significantly larger values in phase standard deviation(51.4°±14.0° vs.34.0°±15.0°),bandwidth(172.9°±39.8° vs.128.7°± 49.9°),sum thickening score(STS,29.5±11.1 vs.17.8 ± 13.2),sum motion score(42.9 ± 11.5 vs.33.0 ± 19.0)and scar area(17.7±12.4%vs.7.0 ± 7.9%).Fourteen patients received both PET and cardiac CMR scanning.were performed comparison between the presence of Scar by PET and LGE by CMR.The presence of scar and LGE was moderate correlation(McNemer's test P=0.5;Kappa=0.44,P=0.047).Cox regression analysis showed that phase standard deviation,bandwidth,STS and scar size were associated with VA occurrence.Cut-off values for predicting VA,which identified by Youden's index,for PSD,bandwidth,scar tissues and STS were 36.6°(sensitivity of 58.82%and specificity of 88.24%),157.6°(sensitivity of 67.65%and specificity of 76.47%),9.5%(sensitivity of 64.71%and specificity of 76.47%),and 26.5(sensitivity of 63.64%and specificity of 73.33%),respectively.The area under curve(AUC)s of PSD,bandwidth,STS and scar area were 0.78,0.73,0.72 and 0.71,respectively.Survival analysis showed the patients with more risk factors had significantly higher risk for the prevalence of VA,with 64.7%,26.3%,and 6.67%for those with 4,1-3,and 0 risk factors,respectively(logrank P=0.0011)Conclusions.Increased dyssynchrony,higher STS and larger left ventricular scar burden quantified by 18F-FDG PET may indicate a higher VA incidence after ICD placement.18F-FDG PET can be considered to assess these global and regional variables to identify the patients with high risk of VA.Background.It is important to evaluate the myocardial characteristics of patients with ventricular arrhythmia(VA)for identifing the risk factors of VA,preventing sudden cardiac death(SCD)and selecting proper patients who will benefit from implantable cardioverter defibrillator(ICD).Due to the different etiology and heterogeneity of myocardial substrate,the myocardial evaluation of patients with VA risk should not only be considered as a continuous whole,but also be performed segmental analysis.This present study was to assess the additional value of systolic wall thickening to viability assessment in predicting ventricular arrhythmia by 18F-fluorodeoxyglucose positron emission tomography(18F-FDG PET)in patients with ICD placement.Methods.We performed a prospective observational study and recruited 56 patients who required ICD placement.Both pre-procedure 99mTc-MIBI gated SPECT MPI and 18F-FDG PET myocardial metabolic image scans were performed.For each patient assessment,a standard 17-segment of the left ventricle proposed by the American Heart Association was applied.QGS software was used for the following cardiac function variables:wall thickening(WT),and wall motion(WM),left ventricular end diastolic volume(LVEDV),left ventricular end systolic volume(LVESV),left ventricular ejection fraction(LVEF).QPS software was used to grade 99mTc-MIBI and 18F-FDG uptakes in all segments and quantitative analysis of scar area,and hibernating myocardium.The patient's follow-up was done every 6-12 months after ICD implantation,or when necessary.Associations between image results and VA were analyzed.Results.In the 56 patients(40 males,54.7 ± 16.8 years)analyzed,18(32.14%)developed VA,Regional function(wall motion/thickening)and viability pattern.(normal,mismatch,scar)were evaluated for 952 segments.Compared with patients without VA,patients with VA had significantly lower frequency of normal wall thickening segments and wall motion segments(19%vs.37%and 15%vs.25%,all the P<0.001),higher frequency of absent wall thickening segments and dyskinetic segments(28%vs.12%and 9%vs.4%,P<0.001 and P<0.05,respectively).In light of viability of segments,patients with VA has lower frequency of normal wall thickening and higher absent wall thickening segments in normal perfusion(30%vs.44%and 18%vs.8%,P<0.05 and P<0.001,respectively),hibernating myocardium(11%vs.33%and 33%vs.16%,P<0.001 and P<0.05,respectively)and scar segments respectively(3%vs.14%and 44%vs.24%,all the P values<0.001).The distribution of WM segments showed that more normal wall motion segments were found in scar segments of patients without VA(14%vs.0%,P<0.001).Logistic regression analysis for segmental assessment showed that wall thickening and scar(OR,1.513,95%CI 1.014-2.258,P=0.043)were associated with VA occurrence.The higher degree of wall thickening reduced,the greater association with VA(OR and 95%CI for score 1 vs.2 vs.3 were 1.873[1.111-3.156]vs.2.587[1.470-4.554]vs.4.907[2.596-9.276],respectively).Cox regression analysis for global cardiac assessment showed that higher STS score and larger scar size were associated with VA occurrence(HR[95%CI],1.049[1.003-1.097],1.040[1.003-1.079],respectively).Kaplan-Meier survival curve showed that patients with absent wall thickening more likely to experience VA with or without scar(P=0.002 or P<0.001).Patients with scar more likely to experience VA with wall thickening reduced(P=0.004),whereas outcomes not significantly different from patients without wall thickening abnormal whether with or without scar(P=0.668).Conclusions.In this study,18F-FDG PET was used to segmental evaluate the WT of ICD patients,which can better evaluate the regional cardiac function on the basis global cardiac function.Furthermore,assessment of myocardial wall thickening in addition to scar segments allowed better identified the patients with high risk factors of VA occurrence.