Comparing Predictors Influencing Restenosis Following High-Dose Drug-Coated Balloon Angioplasty and Fluoropolymer-Based Drug-Eluting Stenting in Femoropopliteal Artery Lesions.

PURPOSE: Despite widespread use of anti-restenosis devices, drug-coated balloons (DCBs) and drug-eluting stents (DESs), their appropriate use for femoropopliteal (FP) lesions has not been well investigated and the risk factors for restenosis have not been compared. To investigate risk factors associated with restenosis after endovascular therapy using DCB and DES for contemporary FP lesions. MATERIALS AND METHODS: This single-center, retrospective, observational study evaluated 378 FP lesions in 273 patients treated with DCB (278 lesions in 193 patients) or DES (120 lesions in 106 patients). The DCB used was high-dose DCB (IN.PACT, Admiral. Medtronic, Inc.) and DES was fluoropolymer-based DES (ELUVIA, Boston Scientific). Vessel preparation failure was defined as a residual stenosis of ≥50% and a dissection grade of D or greater on pre-dilatation angiography. The outcome measure was restenosis, and factors associated with restenosis in the DCB and DES groups were assessed using a Cox proportional hazards model. RESULTS: The 2-year restenosis rate was not significantly different between the DCB and DES groups (29%±4% vs. 24%±5%, p=0.42). Interaction analysis demonstrated that popliteal lesions and plaque burden of ≥50% were restenosis-related factors for DES but not for DCB, whereas vessel preparation failure was a factor for DCB but not for DES (p<0.05). Vessel diameter of <6 mm and nodular calcification were risk factors in both groups (p<0.05). CONCLUSION: In contemporary FP lesions, smaller vessels and nodular calcification were shared restenosis-related factors for high-dose DCB and fluoropolymer-based DES. Popliteal lesions and plaque burden of ≥50% were restenosis-related factors for fluoropolymer-based DES and vessel preparation failure for high-dose DCB. CLINICAL IMPACT: Shared and differential restenosis-related factors after endovascular therapy using high-dose drug-coated balloons (DCBs) and fluoropolymer-based drug-eluting stents (DESs) in contemporary femoropopliteal (FP) lesions are unclear. This single-center retrospective study included 378 FP lesions in 273 patients with lower-extremity arterial disease (high-dose DCB, 278 lesions in 193 patients; fluoropolymer-based DES, 120 lesions in 106 patients). Smaller vessels and calcified nodules were shared restenosis-related factors for both high-dose DCB and fluoropolymer-based DES, whereas popliteal lesions and plaque burden of ≥50% were restenosis-related factors for fluoropolymer-based DES and vessel preparation failure for high-dose DCB.

Clinical Impact of the Size of Drug-Coated Balloon Therapy on Restenosis Rate in Femoropopliteal Lesions.

PURPOSE: Although the size of drug-coated balloons (DCBs) is determined according to the vessel diameter during femoropopliteal (FP)-endovascular therapy (EVT), the measurements of the vessel diameter vary among modalities and its definitions. The aim of this study was to reveal whether the DCB size fitting (1) angiographically-measured lumen diameter (Angio-lumen size), (2) intravascular ultrasound (IVUS)-measured lumen diameter (IVUS-lumen size), or (3) IVUS-measured external elastic membrane (EEM) diameter (IVUS-EEM size) would be beneficial in restenosis occurrence. MATERIALS AND METHODS: This retrospective, single-center study included 231 de novo FP lesions in 165 patients with peripheral artery disease treated with IN.PACT Admiral DCB under IVUS evaluation. The reference vessel diameter was evaluated as the lumen or EEM diameter at the healthy site distal to the lesion. We retrospectively determined whether the DCB size was close to (ie, equal to or different by <0.5 mm from) Angio-lumen size, IVUS-lumen size, and IVUS-EEM size. The association of the size of DCB with restenosis risk was investigated. RESULTS: The mean lesion length was 13 ± 9 cm and the prevalence of chronic total occlusion was 18%. During a mean follow-up period of 17 ± 9 months, restenosis occurred in 26% of lesions. Lesions treated with a DCB of IVUS-EEM size had a lower 2 year restenosis rate than those treated with a DCB over/under IVUS-EEM size (19.7 ± 5.7% vs 34.5 ± 4.7%, p=0.02 by the log-rank test), while the restenosis rate was not significantly different between DCBs of Angio-lumen size or IVUS-lumen size and those over/under the size (both p>0.05). The multivariate Cox regression analysis revealed that DCBs of IVUS-EEM size were independently associated with a reduced risk of restenosis (adjusted hazard ratio 0.50; 95% confidence interval 0.27-0.95; p=0.03). CONCLUSION: The DCBs of IVUS-EEM size, but not of Angio-lumen size or IVUS-lumen size, were associated with a reduced risk of restenosis after FP-EVT. Determining the DCB size according to IVUS-evaluated EEM diameter would be potentially beneficial in restenosis occurrence.

Factors in Sufficient Endovascular Vessel Preparation for Severely Calcified Femoropopliteal Lesions.

BACKGROUND: Vessel preparation for endovascular treatment (EVT) is important but because the contributory factors for favorable outcomes are not yet known, we conducted the present study to elucidate the factors associated with sufficient vessel preparation for severely calcified femoropopliteal (FP) lesions.Methods and Results: This was a single-center retrospective observational study of 97 patients (mean age, 75±8 years, 76% male) with 106 de novo severely calcified FP lesions who underwent EVT under intravascular ultrasound (IVUS) evaluation. The lesion definition was 360° of superficial calcification on IVUS. The primary outcome measure was sufficient vessel preparation, which was defined as successful cracking of severely calcified lesions evaluated by IVUS after predilation. The mean lesion length was 200±103 mm, and chronic total occlusion was present in 38% of patients. According to the greater difference between the preballoon size and the lumen diameter of the severely calcified lesion, the frequency of sufficient vessel preparation increased (odds ratio, 4.68; 95% confidence interval, 2.09-10.49; P<0.01). Balloon type (noncompliant, P=0.80; scoring: P=0.25) and pressure (P=0.27) were non-contributory. CONCLUSIONS: The difference between the lumen diameter at the severely calcified FP lesion site and the preballoon dilatation diameter was the sole factor contributing to sufficient vessel preparation.

Impact of intravascular ultrasound parameters and platelet reactivity on primary patency after drug-coated balloon angioplasty for femoropopliteal artery disease.

Although the superiority of DCBs to uncoated balloon angioplasty for the treatment of femoropopliteal (FP) lesions has been demonstrated, the association of clinical factors, including anatomical features evaluated by intravascular ultrasound (IVUS) and platelet reactivity, with the loss of patency has not been systematically studied. The current prospective, observational study enrolled 160 consecutive patients (male 67.5%, mean age 74.7 ± 9.7 years) with 213 FP lesions treated with DCBs under IVUS evaluation. The platelet reactivity was measured in P2Y12 reaction units for all of the patients at the DCB treatment. The primary end point was primary patency at 12 months, while the secondary end points were freedom from target lesion revascularization (TLR), all-cause death, major target limb amputation and bleeding events at 12 months. Mean lesion length was 11.9 ± 9.4 cm and 34 (16.0%) were chronic total occlusions (CTOs). Thirty-four (16.0%) were severely calcified lesions. Primary patency by Kaplan-Meier estimate was 79.2% at 12 months, while the 12-month freedom from TLR, all-cause death and bleeding events were observed in 89.1%, 93.4% and 97.4%, respectively. There were no major target limb amputations through 12 months. Multivariate analysis showed that subintimal angioplasty for CTO lesions was a sole risk factor for loss of 12-month primary patency, while other IVUS parameters and platelet reactivity were not.

Identification of post-procedural optical coherence tomography findings associated with the 1-year vascular response evaluated by coronary angioscopy.

Optical coherence tomography (OCT) provides higher resolution intravascular imaging and allows detailed evaluations of stent implantation sites post-percutaneous coronary intervention (PCI). Coronary angioscopy (CAS) can evaluate the vascular response after drug-eluting stent (DES) implantation. The post-PCI OCT findings that are associated with the CAS 1-year vascular response have not been known. We enrolled 168 lesions from 119 patients who underwent OCT-guided PCI using DES and follow-up CAS observation at 1 ± 0.5 year from August 2012 to December 2019. Outcome measures were sufficient neointimal coverage (NIC) defined as stent struts embedded in the neointima, subclinical intrastent thrombus, and vulnerable stented segments defined as those with angioscopic yellow or intensive yellow color 1 year after PCI. We identified the post-PCI OCT findings associated with these CAS findings. Sufficient NIC, subclinical intrastent thrombus, and vulnerable stented segment were detected in 85 lesions (51%), 47 lesions (28%), and 54 lesions (32%), respectively. A multivariate analysis demonstrated that malapposed struts were negatively associated with sufficient NIC (odds ratio 0.87; 95% CI 0.76-0.99; p = 0.029). However, no specific OCT findings immediately after PCI were associated with subclinical intrastent thrombus or vulnerable stented segment. Malapposition immediately after PCI was negatively associated with sufficient NIC at 1 year even without associations between post-PCI OCT findings and subclinical intrastent thrombus or vulnerable stented segment.

Intravascular ultrasound-based decision tree model for the optimal endovascular treatment strategy selection of femoropopliteal artery disease-results from the ONION Study.

BACKGROUND: The role of catheter-based imaging in peripheral interventions for lower extremity artery disease (LEAD) has increased with percutaneous interventions. To clarify the relation between intravascular ultrasound (IVUS) information and procedure selection strategy for endovascular treatment therapy (EVT) of the femoropopliteal artery in the real-world clinical settings wherein new endovascular technologies (NETs), including drug-coated balloon (DCB), drug-eluting stent (DES), and covered stent-graft (CS). Our retrospective multicenter analysis examined symptomatic 970 patients treated by EVT for de novo femoropopliteal lesions with IVUS guidance. The decision tree analysis was performed retrospectively to determine the association of IVUS and angiography parameters with the strategy selection of endovascular procedures. We divided the study population according to the developed tree, and identified the most popular strategy selection in each subgroup. We finally examined whether the restenosis risk would be different among respective subgroups of the tree. RESULTS: During the study periods, plain old balloon angioplasty, DCB, and bare nitinol stent were most frequently selected (25.3%, 23.9%, and 23.8%, respectively). The drug-eluting stent (DES), covered stent (CS), and spot stent strategies were used in 7.3%, 11.5%, and 8.1%. NETs had the lowest restenosis risk in the overall population. The decision tree had a depth of six branches and divided the patients into 11 subgroups by IVUS and angiography parameters. The restenosis rate was similarly low among these 11 subgroups when the most popular NET in each subgroup was selected (P = 0.94). CONCLUSIONS: The use of IVUS data along with angiography data would standardize the selection of endovascular procedures and can improve patency outcomes if NETs are used properly.

Clinical expert consensus document on standards for lower extremity artery disease of imaging modality from the Japan Endovascular Treatment Conference.

Imaging modalities have developed to provide precise information in the assessment of lower extremity artery disease (LEAD), including both quantitative measurements and morphological assessment. However, a lack of standardization for the evaluation methods introduces inconsistency and potential risk. This consensus document from Japan Endovascular Treatment Conference (JET) summarizes the methods of measurement and assessment of intravascular ultrasound (IVUS), optical frequency domain imaging (OFDI), and angioscopy. We propose standardized approaches for the evaluation of these modalities in endovascular therapy (EVT).

Cutting balloons versus conventional balloons for treating patients with coronary artery disease presenting with moderate-to-severely calcified lesions: impact on post-interventional minimum stent area.

Cutting balloons are commonly used to treat patients with coronary artery disease (CAD) presenting with calcified lesions, but the efficacy of cutting balloons has not been elucidated. We aimed to investigate the impact of novel cutting balloons (Wolverine™) relative to conventional balloons on post-interventional stent expansion for coronary calcified lesions. This study was a single-center, retrospective, observational study. We analyzed 636 lesions from 543 patients with moderate-to-severely calcified CAD lesions undergoing intravascular ultrasound (IVUS)-guided percutaneous coronary intervention using cutting balloons or conventional balloons prior to drug-eluting stent implantation. The primary outcome was post-interventional minimum stent area (MSA) evaluated by IVUS. Propensity score matching was performed to adjust for baseline characteristics. The interaction effects between balloon type and baseline characteristics were also assessed in MSA > 5.5 mm2. Data on pairs of lesions (n = 168) were extracted with no major intergroup differences in baseline characteristics. Post-interventional MSA was not significantly different in the two groups (5.3 ± 2.0 mm2 versus 5.1 ± 1.9 mm2, P = 0.42). Subgroup analysis indicated the subgroup (calcium arc > 180°) showed the qualitative interaction of balloon type effect (P for interaction = 0.056) and the use of cutting balloons was more favorable for lesions with calcium arc ≤ 180° (adjusted odds ratio 4.10, 95% confidence interval 1.14-14.69). The use of cutting balloons did not demonstrate the beneficial effect on post-interventional MSA relative to conventional balloons for patients with CAD presenting moderate-to-severely calcified lesion. However, the use of cutting balloons was more favorable for lesions with calcium arc ≤ 180° to obtain the optimal MSA.

Left Atrial Localized Low-Voltage Areas Indicate Whole Left Atrial Electrophysiological Degeneration in Atrial Fibrillation Patients.

BACKGROUND: The efficacy of ablation targeting low-voltage areas (LVAs) is controversial, although LVA presence is well known to be associated with atrial fibrillation (AF) recurrence after ablation. AF substrate may not localize within LVAs.Methods and Results:This observational study enrolled 405 consecutive patients who underwent an initial AF ablation procedure. The left atrial (LA) voltage map was obtained after pulmonary vein isolation. LVAs were defined as areas with voltage <0.5 mV. To estimate whole LA electrophysiological degeneration, mean regional voltage at each of the 6 regions and LA total conduction velocity were measured. LVAs existed in 143 of 405 (35.3%) patients. Patients with LVAs demonstrated lower mean regional voltages throughout all 6 regions compared to those without LVAs (1.3 [1.8, 0.8] vs. 0.6 [1.0, 0.2] mV for the anterior wall, P<0.001). In contrast, LA conduction velocity was lower in patients with LVAs than in those without (0.89 [1.01, 0.74] vs. 0.93 [1.03, 0.87] m/s, P<0.001). Multivariate analysis revealed that low LA total conduction velocity and a higher number of regions with mean voltage reduction were independently associated with AF recurrence, although LVA presence was not. CONCLUSIONS: Patients with localized LA LVAs were characterized by whole LA electrophysiological degeneration as assessed by mean regional voltage and conduction velocity. In addition, whole LA electrophysiological degeneration parameters were well associated with AF recurrence.

Early- and Middle-Phase Angioscopic Assessment of Arterial Healing Following Current Drug-Eluting Stent Implantation in Patients With Acute Coronary Syndrome.

Background: Drug-eluting stents (DESs) have been widely used for the treatment of acute coronary syndrome (ACS). However, there are few reports on early- and middle-phase arterial repair after DES implantation in ACS patients. Methods and Results: Coronary angioscopy (CAS) findings covering the early and middle phases (mean [±SD] 4±1 and 10±2 months, respectively) of arterial healing after second- and later-generation DES placement between May 2009 and January 2020 were extracted from the Kansai Rosai Hospital Cardiovascular Center database. Neointimal coverage (NIC), yellow color intensity, and the incidence of thrombus adhesion were compared between ACS and chronic coronary syndrome (CCS) in the early (54 stents of 47 lesions, 38 ACS patients; 86 stents of 70 lesions, 52 CCS patients) and middle (179 stents of 154 lesions from 136 ACS patients; 459 stents of 374 lesions from 287 CCS patients) phases. In the early phase, NIC, the incidence of thrombus adhesion (ACS, 39.1%; CCS, 38.0%), and maximum yellow color grade were similar between the 2 groups. In the middle phase, although the maximum yellow color grade was significantly higher in the ACS group (P=0.013), NIC and the incidence of thrombus adhesion (ACS, 24.6%; CCS, 23.4%) were similar in the 2 groups. Conclusions: Arterial healing assessment with CAS showed that NIC and the incidence of thrombus adhesion after DES implantation were similar between ACS and CCS patients.

Arterial Healing 10 Months After Implantation of an Ultrathin-Strut, Biodegradable-Polymer, Sirolimus-Eluting Stent　- An Angioscopic Study.

Background: The OrsiroTM ultrathin-strut, biodegradable-polymer, sirolimus-eluting stent (O-SES) has specific characteristics regarding its components and has demonstrated comparable clinical outcomes compared with durable-polymer, drug-eluting stents (DES). However, arterial repair following deployment of the O-SES has not been elucidated to date. Methods and Results: Using data from the Kansai Rosai Hospital database between November 2010 and September 2020, we analyzed coronary angioscopy (CAS) findings a mean (±SD) of 10±2 months after implantation of an O-SES, a durable-polymer everolimus-eluting stent (XienceTM; X-EES), or a biodegradable-polymer everolimus-eluting stent (SynergyTM; S-EES). Neointimal coverage (NIC), yellow color intensity of the stented segment, and the incidence of thrombus adhesion were compared between the O-SES (66 stents from 42 patients), X-EES (119 stents from 87 patients), and S-EES (132 stents from 88 patients). NIC was significantly thinner for the O-SES than S-EES (P<0.001), but was similar between the O-SES and X-EES (P=0.25). Yellow color intensity was significantly greater for the O-SES than X-EES (P<0.001), but similar between the O-SES and S-EES (P=0.51). The incidence of thrombus adhesions was similar in all 3 groups. Conclusions: O-SES and X-EES resulted in similar inhibition of NIC and both resulted in a thinner NIC than with S-EES. In addition, O-SES exhibited a similar degree of thrombus adhesion as the other DES, suggesting similar thrombogenicity.

Predictive Factors for Restenosis Following Stent-Supported Endovascular Therapy with Intravascular Ultrasound Evaluation for Femoropopliteal Chronic Total Occlusion.

PURPOSE: To determine the predictive factors for in-stent restenosis (ISR) following stent-supported endovascular therapy (EVT) with intravascular ultrasound (US) evaluation for femoropopliteal chronic total occlusion. MATERIALS AND METHODS: This was a single-center, retrospective, observational study. The study included 276 lesions in 251 patients who underwent stent-supported EVT with intravascular ultrasound evaluation for femoropopliteal chronic total occlusion from July 2012 to June 2019. The wire passage route was assessed using intravascular US, and lesions were classified accordingly into 2 groups: intraluminal and subintimal passage. In this study, the intraluminal group was further divided into 3 subgroups by severity of calcification: none, <180°, and ≥180° circumferential. The subintimal group was further divided into 2 subgroups: subintimal passage without or with calcification. The primary outcome measure was ISR. Cox proportional hazards regression was used to determine the association of clinical characteristics with ISR rates. RESULTS: The mean follow-up period was 19 months ±16, during which time ISR was observed in 31% of lesions. After multivariate analysis, an increased degree of plaque burden (hazard ratio [HR] = 1.101) and subintimal passage with calcification (HR = 3.408) were associated with an increased risk of ISR; a larger distal external elastic membrane area (HR = 0.898) and use of a stent graft (HR = 0.130) were significantly associated with a reduced risk of ISR. CONCLUSIONS: This study revealed that factors associated with ISR after stent-supported EVT with intravascular US evaluation were distal external elastic membrane area, plaque burden, subintimal passage with calcification, and use of a stent graft.

Improved crossability with novel cutting balloon versus scoring balloon in the treatment of calcified lesion.

Cutting balloons and scoring balloons are commonly used for the preparation of calcified lesion. However, problems with crossability occasionally limit the use of cutting balloons. We prospectively selected 173 calcified lesions treated using a novel cutting balloon (Wolverine™, C group). As control, we retrospectively analyzed 146 calcified lesions treated using a scoring balloon (Lacrosse NSE ALPHA™, S group). Either intravascular ultrasound (IVUS) or optical coherence tomography (OCT) was used by the operator's discretion. The primary outcome was delivery success, which was defined as successful passage to the target lesion immediately after IVUS or OCT evaluation. The secondary outcome was acute cross-sectional area (CSA) gain, which was defined as post-interventional minimum stent area minus pre-procedural minimum lumen area. A multivariate analysis evaluated the independent predictors for delivery success. The delivery success rate was significantly higher in the C group versus the S group (90.8% versus 79.5%, P = 0.006). However, the acute CSA gain was similar between the two groups (IVUS: 3.2 ± 1.8 mm2 versus 3.4 ± 1.9 mm2, P = 0.53; OCT: 3.6 ± 1.4 mm2 versus 4.1 ± 1.9 mm2, P = 0.11). Usage of cutting balloon was an independent predictor for delivery success even after the adjustment for the patient and lesion characteristics [odds ratio (OR): 2.72 (95% confidence interval 1.38-5.33), P = 0.004] as well as the procedural characteristics [OR: 2.34 (1.15-4.86), P = 0.018]. Novel cutting balloons demonstrated better crossability and similar acute CSA gain compared with scoring balloons in calcified lesion.

Angioscopic assessments and clinical outcomes one year after polymer-free biolimus A9-coated coronary stent implantation.

BACKGROUND: Polymer-free biolimus A9-coated coronary stent (DCS) has novel features which lead to the expectation of better arterial healing. However, comparisons of intravascular status between DCS and drug-eluting stents (DES), and robust real-word clinical assessments of DCS have been lacking to date. METHODS: From September 2017 to September 2018, we evaluated the intra-vascular status of 74 DCS implanted in 55 lesions from 43 patients using coronary angioscopy (CAS) approximately one year after implantation from a cohort of 219 lesions in 158 patients. We set 239 second-generation durable-polymer DES (DP-DES) implanted in 211 lesions from 180 patients from a cohort of 2652 lesions in 1914 patients as the control. Angioscopic images were analyzed to determine (1) the dominant degree of neointimal coverage (NIC) over the stent; (2) the heterogeneity of NIC; (3) yellow color grade of the stented segment; and (4) the presence of intra-stent thrombus. The primary outcome was the incidence of thrombus and secondary outcomes were the other CAS findings, and the 1-year clinical outcomes which included target lesion revascularization (TLR) and major adverse cardiac events (MACE). To minimize inter-group differences in baseline characteristics, propensity score matching was performed for clinical outcomes. RESULTS: Incidence of thrombus adhesion was similar in DCS and DP-DES groups (28.4% versus 22.6%, p=0.31). However, the dominant NIC grade was significantly higher in DCS (p<0.001), while NIC was more heterogeneous in DCS than in DP-DES (p=0.001). Maximum yellow color grade was similar (p=0.22). After propensity score matching, 202 lesion pairs from 146 patient pairs were retained for analysis. The cumulative incidence of TLR (4.6% versus 3.8%, p=0.38) and MACE (11.6% versus 11.7%, p=0.84) was similar for DCS and DP-DES. CONCLUSIONS: DCS showed thrombus adhesion and clinical outcomes at 1 year similar to DP-DES. DCS can thus be used with similar safety and efficacy as DP-DES.

Angioscopic Assessments at 3 Months After Fluoropolymer-Based Paclitaxel-Eluting Stent Implantation for Femoropopliteal Endovascular Intervention.

BACKGROUND: The detailed mechanism of early-phase arterial healing after novel fluoropolymer-based paclitaxel-eluting stent (PES) implantation in the femoropopliteal (FP) lesions has not been elucidated.Methods and Results:We evaluated the intravascular status of 20 PES implanted in 11 FP lesions of 9 patients using angioscopy at approximately 3 months after implantation. Angioscopic images were analyzed to determine (1) the dominant degree of neointimal coverage (NIC) over the stent; (2) the extent of uncovered struts; and (3) the presence of intrastent thrombus. NIC was classified into 4 grades: grade 0, stent struts fully visible; grade 1, stent struts bulging into the lumen although covered; grade 2, stent struts embedded in neointima, but translucently visible; grade 3, stent struts fully embedded and invisible. The extent of uncovered struts was scored as follows: score 0, no uncovered struts of the entire stent; score 1, uncovered struts area approximately <30% of the stent; and score 2, uncovered struts area approximately ≥30% of the stent. In total, 90% of stents demonstrated grade 1 dominant NIC and 10% showed grade 2 dominant NIC; 85% of stents showed an uncovered stent score of 0, and the remainder had a score of 1. Thrombus was observed in all stents. CONCLUSIONS: Widely uncovered stent struts were not observed by angioscopy at 3 months after PES implantation in these FP lesions, even with the detection of thrombus adhesion.

Clinical utility of local impedance monitoring during pulmonary vein isolation.

INTRODUCTION: Local impedance (LI) at the tip of ablation catheter can be measured using a recently available technology. We aimed to explore target LI measurements at each radiofrequency application (RFA) for creating sufficient ablation lesions during pulmonary vein (PV) isolation. METHODS: This prospective study included 15 consecutive patients scheduled to undergo an initial ablation of paroxysmal atrial fibrillation (AF). Circumferential ablation around both ipsilateral PVs was performed using a 4-mm irrigated ablation catheter with an LI sensor. Point-by-point ablation was used with a 4-mm inter-ablation-point distance. Operators were blinded to LI measurements during the procedure. Creation of sufficient ablation lesions was assessed by the absence of a conduction gap. RESULTS: After first-pass encircling PV antrum ablation, left atrium to PV conduction remained in 12 of 30 (40%) ipsilateral PVs. Mapping using the minibasket catheter identified 48 ablation points through which the propagation wave entered the PV. At ablation points with a gap, the LI drop during RFA was half that at points without a gap (12 ± 7 vs. 23 ± 12 Ω; p < .001). The generator impedance drop did not differ between ablation points with and without a gap (12 ± 7 vs. 14 ± 10 Ω; p = .10). An LI drop of 13.4 Ω predicted sufficient lesion formation without a gap with a sensitivity of 0.78, specificity of 0.75, and predictive accuracy of 0.75. CONCLUSION: An LI drop of 13.4 Ω at each RFA under the conditions of a 4-mm inter-ablation-point distance and RFA duration ≥20 s may facilitate creation of sufficient lesions during PV isolation.