| BackgroundLeft atrial flutter(AFL)often occurs after atrial fibrillation(AF)ablation or congenital heart disease surgery,especially when the ablation line is incomplete or conduction over the ablation line is restored.As for the limited role of antiarrhythmic medication in this complex clinical scenario,catheter ablation has progressively attracted increasing attention as the potentially definitive treatment option for these arrhythmias.Left AFL in patients without previous atrial surgery or catheter ablation have been reported in recent years.Spontaneous scar/low-voltage zones(LVZs)in the left atrium(LA)are considered as potential substrates for AFL.But the causes of spontaneous scar/LVZ,the mechanism of such AFL and the efficacy of radiofrequency ablation remain unclear.ObjectivesThe purpose of this study is to investigate the clinical,electrophysiological characteristics and outcome of radiofrequency ablation of left AFL in patients without previous atrial surgery or catheter ablation,so as to provide certain reference for subsequent diagnosis and treatment.MethodsWe conducted a retrospective study on left AFL patients without previous atrial surgery or catheter ablation in our hospital from January 2016 to December 2022.Baseline characteristics,mapping and ablation procedure and outcome were analyzed.Differences between patients with different types of AFL and whether they are complicated with AF,and the influence of various factors on prognosis were analyzed.Results1.Forty-two patients were included in this study,including 22 female patients(52.4%)with a median age of 67.0(59.0,73.0)years.Thirty-six patients(85.7%)had paroxysmal AFL and 6 patients(14.3%)had persistent AFL.The most common clinical comorbidity was hypertension(50%),followed by heart failure 45.2%.27 patients(64.3%)had concomitant AF.The LA diameter,LA volume and right atrial volume were significantly higher in the lone AFL group than those in the group with concurrent AF(P<0.05).2.A total of 51 types of left AFL were mapped.By investigating the first type of AFL during mapping,16,16 and 10 patients were classified as mitral isthmus(MI)dependent AFL,roof-dependent AFL and anterior wall scar-related AFL,respectively.LA scar/LVZ were found in 20 patients(47.6%)by voltage map under sinus rhythm or AFL,while 19(95%)were on the anterior wall,3 on the posterior wall and 2 had scars on both the anterior and posterior walls.3.Analysis of risk factors of spontaneous scar/LVZ on the anterior wall of the LA: in the univariate logistic regression analysis,it was found that: Old age,LA enlargement and larger ascending aortic diameter are risk factors for left anterior wall scar/LVZ.Old age and left atrial enlargement were still independent risk factors for spontaneous LA anterior scar/LVZ in the multivariable analysis(OR=10.78 95%CI 1.27-91.34,P=0.029;OR=17.5795% CI 1.92-160.81,P=0.011).4.Twelve-lead synchronous isoelectric interval in ECG were observed in 50.0%patients,among which 16 patients(76.2%)had scar/LVZ in the LA,and the proportion of patients with scar/LVZ was significantly higher than that in the group without isoelectric interval(4,19.0%)(P<0.001).In most cases(39,92.9%),F wave polarity in V1 lead was positive,and the F wave was low and flat in remaining 2 cases.No statistical difference was found in the polarity of the F wave in the inferior,I or V1 leads among these three types of AFL.Also,there was no significant difference among the three types of AFL regarding TCL(P=0.261).However,a difference in the distribution of coronary sinus activation patterns among the three types of AFL was found.Pairwise,there was a statistically significant difference in coronary sinus activation time(CSAT)between patients with roof-dependent flutter and those with MI-dependent flutter(P=0.008),while there was no difference in CSAT between patients with anterior scar-related flutter and those with MI-dependent flutter and roof-dependent flutter(adjusted P=1,P=0.458).5.Regarding ablation strategies,the proportion of PVI plus line ablation or PVI in the group with concurrent AF was significantly higher than that in the lone AFL group(96.2%vs.43.8%,P<0.001).The acute success rate was 41/42(97.6%)and no serious complications occurred during the operation and postoperative hospitalization in all patients.6.During a median follow-up of 26.0(15.0,40.0)months,atrial arrhythmia recurred in 13 patients(recurrence rate 31.7%),including 10 AFL and 3 AF.The median time to event in the recurrence group was 15.0(4.0,20.0)months.Multivariate Cox regression analysis showed that heart failure or HATCH score ≥2 was a risk factor for recurrent atrial arrhythmia after adjusting for confounding factors(HR=6.06 95% CI 1.31-27.96,P=0.021;HR=5.34 95% CI 1.03-27.73,P=0.046).ConclusionsMI-dependent,roof-dependent and the anterior wall scar-related AFL are the main mechanisms of left AFL in patients without previous atrial surgery or catheter ablation.The proportion of patients concomitant with AF was high and the atria were larger in left AFL alone patients.Old age and left atrial enlargement were independent risk factors for spontaneous left atrial anterior wall scar/LVZ.Catheter ablation of left AFL without previous atrial surgery or catheter ablation has a high acute success rate,but long-term atrial arrhythmia-free survival is far from satisfactory.Heart failure or HATCH score ≥2 is the risk factor for recurrence of atrial arrhythmia. |
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