Evaluation of the cavotricuspid isthmus and right atrium by multidetector-row computed tomography in patients with common atrial flutter

Impact of cavotricuspid isthmus depth on the ablation index for successful first-pass typical atrial flutter ablation

Cavotricuspid isthmus (CTI) linear ablation has been established as the treatment for typical atrial flutter. Recently, ablation index (AI) has emerged as a novel marker for estimating ablation lesions. We investigated the relationship between CTI depth and ablation parameters on the procedural results of typical atrial flutter ablation. A total of 107 patients who underwent CTI ablation were retrospectively enrolled in this study. All patients underwent computed tomography before catheter ablation. From the receiver-operating curve, the best cut-off value of CTI depth was < 4.1 mm to predict first-pass success. Although the average AI was not different between deep CTI (DC; CTI depth ≥ 4.1) and shallow CTI (SC; CTI depth < 4.1), DC required a longer ablation time and showed a lower first-pass success rate (p < 0.01). In addition, the catheter inversion technique was more frequently required in the DC (p < 0.01). The lowest AI sites of the first-pass CTI line were determined in both the ventricular (2/3 segment of CTI) and inferior vena cava (IVC, 1/3 segment of CTI) sides. The best cut-off values of the weakest AIs at the ventricular and IVC sides for predicting first-pass success were > 420 and > 386, respectively. Among patients with these cut-off values, the first-pass success rate was 89% in the SC and 50% in the DC (p < 0.01). Although ablation parameters were not significantly different, the first-pass success rate was lower in the DC than in the SC. Further investigation might be required for better outcomes in deep CTIs.

The deeper the pouch is, the longer the radiofrequency duration and higher the radiofrequency energy needed-Cavotricuspid isthmus ablation using intracardiac echocardiography

BACKGROUND

The aim of this study was to explore whether the pouch depth influenced the radiofrequency (RF) duration and total delivered RF energy for cavotricuspid isthmus (CTI) ablation and define the cutoff value for a deep pouch-specified ablation strategy.

METHODS

This study included 94 atrial fibrillation (AF) patients (56 males, age 68 ± 8.0 years). With intracardiac echocardiography, the isthmus length and pouch depth were precisely measured. After a standard AF ablation, all patients underwent the CTI ablation along the lateral isthmus. If bidirectional block could not be achieved, the ablation catheter was deflected more than 90 degrees to ablate inside the pouch (knuckle-curve ablation).

RESULTS

Seventy-two patients (76.6%) had a sub-Eustachian pouch. Bidirectional block could be achieved in all patients. By a univariate logistic regression analysis, only the pouch depth was significantly correlated with the RF duration (P = .005) and RF energy (P = .006). A multivariate logistic regression analysis also revealed the pouch depth was the sole factor that influenced the RF duration (P = .001) and RF energy (P = .001). Among the 72 patients, 21 patients needed a knuckle-curve ablation. Using a receiver operating characteristic curve, the optimal cutoff value of the pouch depth for a knuckle-curve ablation was 3.7 mm with a sensitivity of 90% and specificity of 69%.

CONCLUSIONS

The sub-Eustachian pouch depth was the sole factor that influenced the RF duration and energy in the CTI ablation. If the pouch was deeper than 3.7 mm, a deep pouch-specified ablation strategy would be needed.

Usefulness of pre-procedure cavotricuspid isthmus imaging by modified transthoracic echocardiography for predicting outcome of isthmus-dependent atrial flutter ablation

BACKGROUND

Anatomic characteristics of the cavotricuspid isthmus (CTI) have been reported to be related to the outcome of atrial flutter ablation therapy. However, preprocedural evaluation of CTI anatomy using modified transthoracic echocardiography to guide atrial flutter ablation has not been well described.

METHODS

Transthoracic echocardiography was prospectively performed before atrial flutter ablation in 42 patients with typical CTI-dependent atrial flutter. A modified apical long-axis view was designed to visualize and evaluate anatomic characteristics of the CTI and Eustachian ridge (ER). A prominent ER, extending from the inferior vena cava to the interatrial septum, is defined as an extensive ER.

RESULTS

Twenty-eight patients had straightforward ablation procedures, and 14 patients had difficult ablation procedures. Two patients with difficult procedures had unsuccessful ablation. Multivariate analysis (using CTI length, the presence of a pouch or recess, ER morphology, and significant tricuspid regurgitation as variables) showed that the presence of extensive ER was the only independent predictor of a difficult ablation procedure. The ablation time in patients with extensive ER (n = 13) was significantly longer than in those patients with nonextensive ER (n = 29) (1,638.4 ± 1,548.3 vs 413.8 ± 195.5 sec, P = .015). The incidence of difficulty in achieving bidirectional isthmus block was also higher in patients with extensive ER (10 of 13 vs four of 29, P < .001).

CONCLUSION

Preprocedural transthoracic echocardiography using a modified apical long-axis view is useful to characterize the morphology of the CTI and the ER. An extensive ER is a strong predictor for difficult ablation of CTI-dependent atrial flutter.

Multidetector row computed tomography may accurately estimate plaque vulnerability: does MDCT accurately estimate plaque vulnerability? (Pro)

Over the past decade, multidetector row computed tomography (MDCT) has become the most reliable and established of the noninvasive examination techniques for detecting coronary heart disease. Now MDCT is chasing intravascular ultrasound (IVUS) in terms of spatial resolution. Among the components of vulnerable plaque, MDCT may detect lipid-rich plaque, the lipid pool, and calcified spots using computed tomography number. Plaque components are detected by MDCT with high accuracy compared with IVUS and angioscopy when assessing vulnerable plaque. The TWINS study and TOGETHAR trial demonstrated that angioscopic loss of yellow color occurred independently of volumetric plaque change by statin therapy. These 2 studies showed that plaque stabilization and regression reflect independent processes mediated by different mechanisms and time course. Noncalcified plaque and/or low-density plaque was found to be the strongest predictor of cardiac events, regardless of lesion severity, and act as a potential marker of plaque vulnerability. MDCT may be an effective tool for early triage of patients with chest pain who have a normal ECG and cardiac enzymes in the emergency department. MDCT has the potential ability to analyze coronary plaque quantitatively and qualitatively if some problems are resolved. MDCT may become an essential tool for detecting and preventing coronary artery disease in the future.

Right atrial scar detection after catheter ablation: Comparison of 2D and high spatial resolution 3D-late enhancement magnetic resonance imaging

RATIONALE AND OBJECTIVES

To prospectively compare the diagnostic performance of two-dimensional (2D) and high spatial resolution three-dimensional (3D) late enhancement magnetic resonance imaging (MRI) for the detection of scar tissue caused by catheter ablation of the right atrium in patients with atrial flutter.

MATERIALS AND METHODS

Forty-seven patients were enrolled. In 16 patients, imaging of the cavotricuspid isthmus was performed before and after catheter ablation, 16 subjects were imaged before, and 15 after catheter ablation, resulting in a total of 63 examinations. MRI included a standard 2D breathhold and a high-resolution navigator-gated 3D T1-weighted gradient-echo inversion-recovery sequence in right and left anterior oblique views. Two readers assessed the subjective image quality on a 4-point scale (1 = excellent) and the presence of late enhancement (blinded/ in consensus).

RESULTS

The average image quality was 1.6 for both imaging approaches. In consensus reading, the sensitivity was 83% versus 100%, specificity 97% versus 89%, accuracy 90% versus 94%, positive predictive value 96% versus 89%, negative predictive value 86% versus 100% for 2D and 3D, respectively. The interobserver agreement was 0.86 for 2D and 0.78 for 3D imaging.

CONCLUSIONS

For the noninvasive identification of scars in the cavotricuspid isthmus after right atrial flutter, ablation 2D imaging was more consistent, whereas 3D sequences showed superior sensitivity for the depiction of late enhancement.

Fusion of multislice computed tomography and electroanatomical mapping data for 3D navigation of left and right atrial catheter ablation

PURPOSE

To assess whether fusion of multislice computed tomography (CT) images with electroanatomical (EA)-mapping data using a new image integration module (CartoMerge) is feasible and accurate to navigate ablation catheters in right and left atrial catheter ablation.

MATERIAL AND METHODS

Twenty-four patients were examined with ECG-gated cardiac multislice CT (64 mm x 0.6mm, 0.33 s) 1 day before left atrial (LA) (15 patients) radiofrequency or right atrial cavotricuspid isthmus ablation (9 patients). CT data were fused with the non-fluoroscopic EA-mapping data by using dedicated software (CartoMerge) and the value of CT was analysed.

RESULTS

In 23/24 (96%) patients, CT images could be fused with the EA-map. The alignment error was 2.16+/-0.35 mm. In 15/15 (100%) patients, CT added relevant anatomical information regarding the course of the esophagus or the pulmonary veins before LA-ablation. CT added useful information in only 3/8 (37.5%) of patients undergoing right atrial cavotricuspid isthmus ablation.

CONCLUSION

3D-navigation of RF-ablation catheters in the atria assisted by image fusion of multislice CT with EA-mapping data is feasible and accurate. CT added relevant anatomical information about the left atrium and the pulmonary veins before LA-ablation, CT also provided information about the course of the esophagus which might help to avoid thermal injury. CT image fusion might be of minor value before right atrial cavotricuspid isthmus catheter ablation.