ABC | Volume 110, Nº5, May 2018

Original Article Chen et al PV anatomy and cryo kinetics Arq Bras Cardiol. 2018; 110(5):440-448 Table 1 – Baseline Characteristics of study population and CB PVI Procedure Parameters Baseline Characteristics Age (years) 56.8 ± 12.5 Gender, male 32(53.3) BMI (kg/m2) 24.6 ± 3.1 AF type, paroxysmal AF 58 (96.7) AF duration (months) 25.5 (12, 69) CHA 2 DS 2 -VASc score 1(0, 2) LAD (mm) 35.2 ± 4.8 LVEF (%) 65.6 ± 5.4 Procedure Parameters Balloon type, 28-mm /23-mm/double 34 (56.7) / 24(40) / 2(3.3) N°. of freeze 10.8 ± 3.2 Acute PVI Patient level * 60(100) With CB only, PV level # 225 (94.5) With CB only, patient level 51(85) Complications 4 (6.7) Phrenic nerve palsy 1 (1.7) Pericardial & pleural effusion 1 (1.7) Left groin hematomas 2 (3.3) Values are n (%), mean ± SD, or median (interquartile range). CB: cryoballoon; PVI: pulmonary vein isolation; PV: pulmonary vein; AF: atrial fibrillation; BMI: body mass index; LAD: left atrial diameter; LVEF: left ventricular ejection fraction (measured from transthoracic echocardiography); CHA 2 DS 2 -VASc score = stroke risk score [cardiac failure, hypertension, age ≥ 75 years (doubled), diabetes, stroke (doubled)‑vascular disease, age of 65–74 years and sex category (female)]. * : PVI with CB ablation only or plus conventional RF ablation. # : 1 right superior and 1 right inferior PV has no potential. Correlation between BNT and BFT (correlation coefficient: 0.77, p < 0.001), and between BNT and BWT (correlation coefficient: - 0.85, p < 0.001) was stronger than that between BFT and BWT (correlation coefficient: - 0.60, p < 0.001) when using 23-mm CB. The same result was found when using 28-mm CB (correlation coefficient: 0.79, - 0.86, and - 0.62, respectively; all p < 0.001). PV anatomy and BNT As mentioned above, D corrected has much stronger correlations with both D long and D short , and BNT has much stronger correlations with the two other kinetic parameters as well, D corrected and BNT were chosen as parameters to investigate the relationship between PV diameter and cryo kinetic parameter. To reflect the maximal biological effect and avoid the confounding effect caused by manipulation between different cycles (e.g., occlusion degree, time of freezing circle), the lowest BNT achieved by using the same size of balloon was chosen to analyze each PV. Correlation analysis revealed that the correlation coefficient between D corrected and BNT was -0.51 when ablation was with 23-mmCB, and it was -0.32 with 28-mmCB (both p < 0.001). Correlation between the two parameters was stronger when using 23-mm CB (see Figure 3). However, there was no significant correlation between value of D short / D long and BNT either using 23- (correlation coefficient: -0.11, p = 0.23) or 28-mm CB (correlation coefficient: -0.09, p = 0.30). In order to investigate the predict value of PV anatomic parameters for cryo kinetic effect, BNT was transformed into a binary variable with a cut-point of -51°C (< -51°C and≥ -51°C) 4 and taken as dependent variable. PV anatomic parameters including D corrected , value of D short / D long , ostium shape, drainage pattern and location were included in logistic regression model as independent variables. Univariate and multivariate analyses revealed that, among the above‑mentioned variables, D corrected [OR, 1.4(95% CI: 1.1 – 1.8), p = 0.004] predicted a BNT of < -51°C when using 23-mm CBs, while an oval shape of PV ostium [OR, 0.3(95%CI: 0.1 – 0.9), p=0.033] and PV locations [left inferior PV: OR, 0.04(95% CI: 0.004 – 0.4), p = 0.005; right superior PV: OR, 4.3(95% CI: 1.2 – 15), p = 0.025] predicted a BNT of < -51°C when using 28-mm CB. However, PV drainage patterns did not predict it when using either 23- or 28-mm CBs. (see Figure 4). Discussion Main findings This study aimed to investigate the relationship between PV anatomy and cryo kinetics during CB ablation. The present study main findings can be summarized as follows: Firstly, MDCT was accurate and useful in pre-procedural evaluation of PV anatomy for CB ablation of AF; D corrected was a better parameter for ostial measurement than D long and D short . Secondly, BNT, BFT and BWT were associated to each other, BNT was a better parameter for evaluating cryo kinetics effect than the latter two. Thirdly, there is an association between D corrected and BNT both when using 23- and 28-mm CBs; D corrected predicted cryo kinetic effect with a BNT of < -51°C when using 23-mm CB, while PV ostial shape and location predicted the effect when using the 28-mm CB. PV anatomy evaluated with MDCT MDCT images can provide accurate and detailed PVs anatomic information. 10 Our study found that variations existed in dimensions, ostial shapes and drainage patterns of PVs among different patients and PV locations, which was consistent with prior studies. 11,13,14 Values of PV ostia D short / D long that we studied were between 0.38~1.00, and only 20.8% PVs (50/240) had a round-shape ostia. Therefore, it is a partial evaluation using only D long or D short as PV ostial dimension. Considering PVs compliance and deformation to adapt the CB during procedure, D corrected , diameter calculated from the perimeter was more reliable. Correlation analysis on PV ostial dimension measurement also demonstrated D corrected was more representative than the two others. 443