
==== Front
Aging Med (Milton)
Aging Med (Milton)
10.1002/(ISSN)2475-0360
AGM2
Aging Medicine
2475-0360
John Wiley and Sons Inc. Hoboken

10.1002/agm2.12350
AGM212350
AGM-2024-0059.R3
Original Article
Original Article
Effects of a prior failed attempt on the outcomes of subsequent chronic total occlusion‐percutaneous coronary intervention
Zheng et al.
Zheng Nai‐Xin 1
Ai Hu 1
Zhao Ying 1
Li Hui 1
Yang Guo‐Jian 1
Tang Guo‐Dong 1
Peng Xi 1
Sun Fu‐Cheng 1
Zhang Hui‐Ping https://orcid.org/0000-0002-0408-0971
1 huipingzhang73@163.com

1 Department of Cardiology, Beijing Hospital National Center of Gerontology Beijing China
* Correspondence
Hui‐Ping Zhang, Department of Cardiology, Beijing Hospital, National Center of Gerontology, No. 1 Dahua Road, Dongcheng District, Beijing 100730, China.
Email: huipingzhang73@163.com

12 8 2024
8 2024
7 4 10.1002/agm2.v7.4 463471
09 3 2024
31 7 2024
© 2024 The Author(s). Aging Medicine published by Beijing Hospital and John Wiley & Sons Australia, Ltd.
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Abstract

Objectives

Patients undergoing a prior failed attempt of chronic total occlusion‐percutaneous coronary intervention (CTO‐PCI) represent a challenging subgroup across all patients undergoing CTO‐PCI. There are limited data on the effects of a prior failed attempt on the outcomes of subsequent CTO‐PCI. We aimed to compare the procedural results and 24‐month outcomes of prior‐failed‐attempt CTO‐PCI with those of initial‐attempt CTO‐PCI.

Methods

Patients who underwent attempted CTO‐PCI between January 2017 and December 2019 were prospectively enrolled. We analyzed the procedural results and 24‐month major adverse cardiac events (MACE) between patients who underwent prior‐failed‐attempt and initial‐attempt CTO‐PCI. MACE was defined as a composite of cardiac death, target vessel‐related myocardial infarction, and ischemia‐driven target vessel revascularization (TVR) during follow‐up.

Results

In total, 484 patients who underwent CTO‐PCI (prior‐failed‐attempt, n = 49; initial‐attempt, n = 435) were enrolled during the study period. After propensity score matching (1:3), 147 patients were included in the initial‐attempt group. The proportion of the Japanese‐CTO (J‐CTO) score ≥2 was higher in the patients who underwent prior failed attempt than in those who underwent initial attempt (77.5% vs. 38.8%, p < 0.001). The retrograde approach was more often adopted in the prior‐failed‐attempt group than in the initial‐attempt group (32.7% vs. 3.4%,  [P< 0.001). Successful CTO revascularization rates were significantly lower in the prior‐failed attempt‐group than in the initial attempt group (53.1% vs. 83.3%, P < 0.001). The multivariate analysis revealed that J‐CTO score ≥2 [odds ratio (OR), 0.359; 95% confidence interval (CI), 0.159–0.812; P = 0.014], intravascular ultrasound procedure (OR, 4.640; 95% CI, 1.380–15.603; P = 0.013), and prior failed attempt (OR, 0.285; 95% CI, 0.125–0.648; P = 0.003) were the independent predictors for successful CTO revascularization. There were no significant differences in major procedural complications (2.0% vs. 0.7%, p = 0.438) and MACE rates (4.1% vs. 8.8%, p = 0.438) between the groups, mainly due to the TVR rate (4.1% vs. 8.2%, P = 0.522).

Conclusions

Compared with initial‐attempt CTO‐PCI, prior‐failed‐attempt CTO‐PCI deserves more attention, since it is associated with a lower successful CTO revascularization rate. Prior failed attempt, J‐CTO score ≥2, and IVUS procedure are the determining factors for predicting successful CTO revascularization. There are no significantly different unfavorable outcomes between patients who undergo prior‐failed‐attempt and initial‐attempt CTO‐PCI.

This study aimed to compare the procedural results and 24‐month outcomes of prior failed attempt CTO‐PCI with those of initial attempt CTO‐PCI. Compared with initial‐attempt CTO‐PCI, prior‐failed‐attempt CTO‐PCI should be paid more attention, which is associated with a lower successful CTO revascularization rate. Prior‐failed‐attempt is the determining factor for predicting successful CTO revascularization. There are no significantly unfavorable outcomes between patients who undergo prior‐failed‐attempt and initial‐attempt CTO‐PCI.

chronic total occlusion
coronary artery disease
percutaneous coronary intervention
National High Level Hospital Clinical Research FundingBJ‐2018‐201 source-schema-version-number2.0
cover-dateAugust 2024
details-of-publishers-convertorConverter:WILEY_ML3GV2_TO_JATSPMC version:6.4.8 mode:remove_FC converted:03.09.2024
Zheng N‐X , Ai H , Zhao Y , et al. Effects of a prior failed attempt on the outcomes of subsequent chronic total occlusion‐percutaneous coronary intervention. Aging Med. 2024;7 :463‐471. doi:10.1002/agm2.12350
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pmc1 INTRODUCTION

The recanalization of chronic total occlusion (CTO) can achieve improved outcomes with a low 1‐year adverse event rate. 1 , 2 , 3 , 4 Despite the introduction of novel devices and advanced techniques, CTO‐percutaneous coronary intervention (PCI) remains a challenging procedure, with variable success rates ranging from 70% to 85% or more, depending on the operator's experience. 5 , 6 Therefore, the number of patients with failed CTO‐PCI is considerable and should not be neglected.

In addition to the complexity of CTO lesions, multiple factors can lead to CTO‐PCI failure, such as insufficient preparation prior to the procedure, excessive procedure time, and contrast volume use as a result of not switching the alternative CTO crossing strategy in time. A prior failed attempt is a key point of the Japanese‐CTO (J‐CTO) scoring system, which is used to predict the likelihood of successful percutaneous recanalization of CTO lesions. 7 There are limited data on the effects of a prior failed attempt on the outcomes of subsequent CTO‐PCI. The present study aimed to compare the procedural results and 24‐month outcomes between CTO‐PCIs with a prior failed attempt and initial‐attempt CTO‐PCIs.

2 METHODS

2.1 Study population

Between January 2017 and December 2019, 484 patients who underwent CTO‐PCI procedures were prospectively enrolled. The patients were divided into two groups based on whether they had a prior failed CTO‐PCI: the initial‐attempt and prior‐failed‐attempt groups (Figure 1). Initial‐attempt CTO‐PCI refers to the first time PCI procedure aimed at the same CTO lesion. Prior‐failed‐attempt CTO‐PCI refers to re‐attempted CTO PCI having previous failure only once, and those with previous failure more than once were excluded. CTO was defined as complete occlusion with an anterograde Thrombolysis in Myocardial Infarction (TIMI) flow grade of 0 in the major epicardial coronary artery for an estimated duration of at least 3 months; this was regardless of the underlying cause (either thrombolysis or stenosis caused by progression of atherosclerosis). The occlusion duration was estimated according to the history of myocardial infarction (MI) in the same target vessel territory, combined with a previous coronary angiogram and changes in electrocardiographic findings. Patients who had received coronary artery bypass grafting or those with side branch occlusion (including the diagonal and marginal branches, as well as post‐descending and post‐lateral arteries) were excluded from this study. CTO‐PCIs were clinically indicated according to the presence of angina or myocardial ischemia. All CTO‐PCIs were electively performed by experienced operators. This study was approved by the Institutional Ethics Committee of the Beijing Hospital. All patients were pretreated with 100–300 mg aspirin, along with a loading dose of 300 mg clopidogrel or 180 mg ticagrelor before CTO‐PCI procedures. Antiplatelet therapy included indefinite aspirin 100 mg/day, clopidogrel 75 mg/day, or ticagrelor 90 mg twice daily for ≥12 months after stent implantation. Finally, clinical baseline characteristics and hospitalization information were recorded.

FIGURE 1 Study flowchart. CTO, chronic total occlusion; PCI, percutaneous coronary intervention.

2.2 Angiographic and interventional procedure variables, and clinical follow‐up

All variables related to angiographic and interventional techniques were analyzed. Multivessel disease (MVD) was defined as ≥75% stenosis in at least two of the major epicardial arteries or their main branch, and left main (LM) disease was defined as ≥50% stenosis of the LM diameter. The syntax score was calculated for each patient to evaluate the severity of coronary artery disease. 8 The J‐CTO score was calculated for each patient undergoing CTO, and a J‐CTO score ≥2 was considered a complicated CTO lesion. 7 An experienced interventionist calculated the syntax and J‐CTO scores. CTO occurring within a previously implanted stent or in occlusive segments within 5 mm proximal or distal to the stent edges was defined as in‐stent restenosis (ISR) CTO. According to the Rentrop classification, the degree of filling of the involved vessel beyond the CTO segment was used to grade the collaterals. 9 The anterograde approach, including antegrade wire escalation (AWE) or antegrade dissection/reentry (ADR), was the first option for crossing CTO lesions. A retrograde approach using retrograde wire escalation (RWE) or retrograde dissection/reentry (RDR) was adopted when the anterograde approach failed. Successful CTO‐PCI was defined as the achievement of <50% residual stenosis in the target CTO lesion with antegrade TIMI flow grade 3 without the occurrence of in‐hospital adverse events, including all‐cause death, tamponade requiring pericardiocentesis, MI, stroke, or repeat target vessel revascularization (TVR) during the index hospitalization. TVR was defined as any repeated percutaneous intervention or surgical bypass of the target vessel. All procedure‐associated adverse events, including procedure‐related death, stroke, periprocedural type 4aMI, major bleeding, coronary perforation with cardiac tamponade requiring intervention, and contrast‐induced nephropathy (increase in serum creatinine level >25% or >0.5 mg/dL at 48 h post‐procedure), were considered major procedural complications. Complete revascularization (CR) was defined as successful treatment of all diseased lesions with ≥75% stenosis in the major epicardial coronary vessels within 30 days of index hospitalization. 10 The primary endpoint was the incidence of major adverse cardiac events (MACE) at the 24‐month follow‐up. MACE was defined as the composite of cardiac death, target vessel‐related MI, and ischemia‐driven TVR.

2.3 Statistical analyses

Continuous variables are presented as mean values ± standard deviations or medians (interquartile ranges), as appropriate. Categorical variables are expressed as numbers (percentages). The chi‐squared or Fisher's exact test was used to compare categorical variables. Student's t‐test or the Mann–Whitney rank‐sum test was used to evaluate the differences among continuous variables according to their distributions.

Propensity scores were calculated using logistic regression, and the clinical baseline and angiographic characteristics were entered into the following model as independent variables: age, hypertension, diabetes mellitus, dyslipidemia, smoking, history of MI, number of diseased vessels, syntax score, target CTO vessel, and Rentrop grade. Propensity scores were used to perform 1:3 nearest‐neighbor matching (one patient with a prior failed attempt CTO‐PCI to three patients with an initial attempt CTO‐PCI). After propensity score matching, the variables between the two groups were compared using Student's t‐test or the Mann–Whitney rank‐sum test. Categorical variables were analyzed using the chi‐squared or Fisher's exact test.

Multivariate analyses were performed using a stepwise multiple logistic regression model to determine the predictors of successful CTO revascularization and are expressed as odds ratios (ORs) with 95% confidence intervals (CIs). Variables showing p < 0.10 in univariate analysis or suggested to be related to successful CTO revascularization of interest according to clinical consideration were adopted as candidate predictors for multivariate analysis. The C‐statistic and goodness‐of‐fit with the Hosmer–Lemeshow test were used to determine the model discrimination. Cumulative MACE curves were constructed using the Kaplan–Meier method, and differences between groups were assessed using the log‐rank test. A two‐tailed p < 0.05 was considered statistically significant for all tests. All statistical analyses were performed using the Statistical Package for the Social Sciences version 26.0 (IBM Corp., Armonk, NY, USA).

3 RESULTS

3.1 Baseline clinical characteristics

In total, 484 patients who underwent CTO‐PCI were enrolled during the study period, with 49 (10.1%) having prior‐failed‐attempt CTO‐PCI. The clinical characteristics of the patients are summarized in Table 1. After propensity score matching, the study population included 196 patients whose clinical characteristics matched those of the control participants. There were no significant differences between the prior‐failed‐attempt and initial‐attempt groups in any of the baseline clinical variables, including risk factors for coronary artery disease, left ventricular ejection fraction obtained by echocardiography on admission, and medication.

TABLE 1 Baseline clinical characteristics for the study patients.

	Total patients	1:3 Propensity‐matched patients	
Prior‐failed‐attempt	Initial‐attempt	P value	Initial‐attempt	P value	
	(n = 49)	(n = 435)		(n = 147)		
Age (years)	60 (52, 66)	64 (56.5, 71.5)	0.064	62.1 ± 12.11	0.964	
Male gender	40 (81.6)	362 (83.2)	0.936	124 (84.4)	0.823	
Current smoker	21 (42.9)	188 (43.3)	1.000	65 (44.2)	1.000	
Hypertension	33 (67.3)	309 (71.2)	0.692	100 (68.0)	1.000	
Diabetes mellitus	19 (38.8)	211 (48.6)	0.247	65 (44.2)	0.617	
Dyslipidaemia	35 (71.4)	275 (63.4)	0.338	101 (68.7)	0.858	
Previous MI	15 (30.6)	106 (24.4)	0.439	44 (29.9)	1.000	
Indication of CTO PCI			0.309		0.157	
Stable angina	14 (28.6)	113 (27.9)		44 (29.9)		
ACS	15 (48.3)	235 (54.0)		88 (59.9)		
Ischemia without symptoms	0	34 (7.8)		11 (7.5)		
Other	20 (40.8)	53 (12.2)		4 (2.7)		
LDL‐C (mmol/L)	1.98 (1.45, 2.76)	2.14 (1.71, 2.69)	0.102	2.07 (1.71, 2.67)	0.349	
eGFR(mL·min−1·1.73−1)	94.72 (76.38, 107.72)	93.48 (77.63, 110.33)	0.922	95.39 ± 24.6	0.787	
LVEF (%)	57.9 ± 10.5	52.2 ± 12.7	0.055	56.4 ± 12.2	0.250	
HFrEF	10 (20.4)	48 (11.0)	0.055	23 (15.6)	0.440	
Medication	
Aspirin	30 (96.8)	404 (99.3)	0.255	146 (99.3)	0.438	
lopidogrel	24 (77.4)	326 (80.3)	0.878	118 (80.3)	1.000	
Ticagrelor	3 (9.7)	70 (17.2)	0.402	27 (18.4)	0.067	
Statins	30 (96.8)	399 (98.3)	0.448	146 (99.3)	0.155	
Note: Values are mean ± SD, n (%), n/N (%), or median (interquartile range).

Abbreviations: ACS, acute coronary syndrome; CTO, chronic total occlusion; eGFR: estimated glomerular filtration rate; HFrEF, heart failure with reduced ejection fraction (EF < 40%); ISR, in‐stent restenosis; LDL‐c, low density lipoprotein cholesterol; LVEF, Left ventricular ejection fraction; MI, myocardial infarction; PCI, percutaneous coronary intervention.

3.2 Angiographic and procedural characteristics

Detailed angiographic and procedural characteristics of both groups are listed in Table 2. The most common target vessels for CTO were the right coronary (41.3%) and left anterior descending (40.9%) arteries, followed by the circumflex artery (17.8%). The prevalence of MVD and LM disease was similar in both groups and presented a similar distribution in the target CTO vessel. Before propensity score matching, patients who underwent a prior failed attempt had greater syntax scores than those who did not. However, this characteristic did not differ between the two groups after propensity score matching. As expected however, compared with the initial‐attempt group, the prior‐failed‐attempt group had significantly higher proportion of ≥2 J‐CTO score, whether performing propensity score matching or not (77.5% vs. 38.8% and 41.1%, both P < 0.001). The percentages of patients with Rentrop grade 3 and ISR CTO were similar between the two groups.

TABLE 2 Angiographic, procedural characteristics and 24‐month outcomes for the patients.

	Total population	1:3 Propensity‐matched patients	
Prior‐failed‐attempt	Initial‐attempt	P value	Initial‐attempt	P value	
(n = 49)	(n = 435)		(n = 147)		
Angiographic characteristics	
Multi‐vessel disease	43 (87.8)	388 (89.2)	0.948	126 (85.7)	0.905	
LM disease	5 (10.2)	24 (5.5)	0.199	5 (3.4)	0.125	
Target CTO vessel			0.123		0.634	
LAD	25 (51)	173 (39.8)		75 (51)		
LCX	4 (8.2)	82 (18.9)		7 (4.8)		
RCA	20 (40.8)	180 (41.4)		65 (44.2)		
Syntax score	19.5 (16.5, 24.5)	23.25 (17.0, 30.5)	0.028	22.5 (16.0, 28.5)	0.235	
J‐CTO score ≥2	31 (77.5)	175 (41.1)	<0.001	57 (38.8)	<0.001	
Rentrop grade 3	21 (52.5)	200 (46.9)	0.612	80 (54.4)	0.62	
ISR CTO	9 (18.4)	75 (17.2)	1.000	28 (19)	1.000	
Procedural characteristics	
Femoral artery access	21 (49.0)	90 (20.5)	<0.001	41 (27.9)	0.009	
Dual injection	28 (57.1)	207 (47.6)	0.204	62 (42.2)	0.069	
Retrograde approach	16 (32.7)	76 (17.5)	0.010	5 (3.4)	<0.001	
IVUS procedure	11 (22.4)	64 (14.8)	0.235	28 (19)	0.757	
Contrast volume (mL)	319.5 ± 121.8	244.1 ± 74.0	0.192	258.6 ± 69.4	0.284	
Fluoroscopy time (min)	66.8 ± 33.4	41.1 ± 26.4	0.067	46.7 ± 28.7	0.218	
Type of intervention			0.549		0.083	
Stent implantation	22 (84.6)	309 (90.4)		117 (95.9)		
Balloon PTCA	4 (15.4)	33 (9.6)		5 (4.1)		
Successful CTO revascularization	26 (53.1)	342 (78.6)	<0.001	122 (83.3)	<0.001	
Non‐CTO lesion PCI	9 (18.8)	167 (38.7)	0.01	55 (37.4)	0.044	
CR	13 (26.5)	203 (46.7)	0.011	76 (51.7)	0.004	
Major procedural complications	1 (2.0)	10 (2.3)	1.000	1 (0.7)	0.438	
Acute stent thrombosis	0 (0)	3 (0.7)	1.000	1 (0.7)	1.000	
Cardiac death	0 (0)	4 (0.9)	1.000	0 (0)	—	
TVR	2 (4.1)	48 (11.0)	0.130	12 (8.2)	0.522	
MACE	2 (4.1)	56 (12.9)	0.072	13 (8.8)	0.438	
MACE in successful CTO revascularization population	1/26 (3.8)	40/342 (11.7)	0.366	10/122 (8.2)	0.722	
Note: Values are mean ± SD, n (%), n/N (%), or median (interquartile range).

Abbreviations: CR, complete revascularization; CTO, chronic total occlusion; ISR, in‐stent restenosis; J‐CTO, Japanese‐CTO; IVUS, intravascular ultrasound; LAD, left anterior descending artery; LCX, left circumflex; LM, left main; MACE, major adverse cardiac event; PCI, percutaneous coronary intervention;RCA, right coronary artery; TVR, target vessel revascularization.

Compared with those who underwent initial attempt, fewer patients who underwent prior failed attempt went through radial artery access, instead of femoral artery access. The retrograde approach was adopted more often in the prior‐failed‐attempt group than in the initial‐attempt group (32.7% vs. 17.5% and 3.4%, P = 0.010 and P < 0.001, respectively). There were no significant differences between the two groups regarding the proportion of cases involving intravascular ultrasound (IVUS) procedures, type of intervention, amount of contrast volume, and fluoroscopy time. Successful CTO revascularization rates were significantly lower in the prior‐failed‐attempt group than in the initial attempt group, even after propensity matching (53.1% vs. 78.6% and 83.3%, respectively; both P < 0.001). More patients in the initial‐attempt group underwent non‐CTO lesion PCI (38.7% and 37.4% vs. 18.8%, P = 0.010 and P = 0.044, respectively) with a higher CR rate (46.7% and 51.7% vs. 26.5%, P = 0.011 and P = 0.004, respectively) than those in the prior‐failed‐attempt group. The incidence of major procedural complications was similar between both groups. No acute stent thrombosis occurred in the prior failed attempt group.

3.3 Predictors of successful chronic total occlusion revascularization in the propensity score matching population by logistic regression analysis

Candidate predictors in the univariate analysis included age, hypertension, diabetes mellitus, dyslipidemia, previous MI, MVD, target CTO vessel, syntax score, J‐CTO score ≥2, Rentrop grade 3, ISR CTO, prior failed attempt, retrograde approach, and IVUS procedure. The final variables entered into the logistic regression model were target CTO vessel, J‐CTO score ≥2, Rentrop grade 3, ISR CTO, retrograde approach, IVUS procedure, and prior failed attempt. Table 3 shows the predictors of successful CTO revascularization in the logistic regression analysis. The multivariate analysis revealed that J‐CTO score ≥2 (OR, 0.359; 95% CI, 0.159–0.812; P = 0.014), IVUS procedure (OR, 4.640; 95% CI, 1.380–15.603; P = 0.013), and prior failed attempt (OR, 0.285; 95% CI, 0.125–0.648; P = 0.003) were independent predictors for successful CTO revascularization.

TABLE 3 Predictors of successful CTO revascularization in the propensity score‐matching population by logistic regression analysis.

	OR	95% CI	P value	
Target CTO vessel	0.749	0.504–1.112	0.152	
J‐CTO score ≥2	0.359	0.159–0.812	0.014	
Rentrop grade 3	1.571	0.731–3.380	0.247	
ISR CTO	0.502	0.203–1.244	0.137	
IVUS procedure	4.640	1.380–15.603	0.013	
Prior‐failed‐attempt	0.285	0.125–0.648	0.003	
Retrograde approach	0.450	0.150–1.344	0.152	
Abbreviations: CI, confidence interval; CTO, chronic total occlusion; ISR, in‐stent restenosis; IVUS, intravascular ultrasound; J‐CTO, Japan‐CTO; PCI, percutaneous coronary intervention; OR, odds ratio.

3.4 Clinical outcomes

The clinical outcomes at 24‐month follow‐up are shown in Table 2. Cardiac death occurred in only four (0.9%) patients, including two patients with in‐hospital death in the initial‐attempt group. Patients who underwent the initial attempt had an insignificantly higher incidence rate of MACEs than those who underwent prior attempt (12.9% and 8.8% vs. 4.1%, P = 0.072 and P = 0.438, respectively), a finding that was mainly accounted for by TVR rates (11.0% and 8.2% vs. 4.1%, P = 0.130 and P = 0.522, respectively). Similar results could be observed in a population with successful CTO revascularization. Figure 2 shows the curves for the probability of 24‐month MACEs according to whether patients underwent prior‐failed‐attempt CTO‐PCI.

FIGURE 2 Kaplan–Meier curves for MACEs according to whether prior failed attempt CTO‐PCI was performed. (A) Propensity‐matched population. (B) After successful CTO revascularization in a propensity‐matched population. CTO, chronic total occlusion; MACE, major adverse cardiac events; PCI, percutaneous coronary intervention.

4 DISCUSSION

Considering the aim of the present study, which was to investigate the effects of prior failed attempt on the outcomes of subsequent CTO‐PCI, the main findings of the study were as follows 1 : prior failed attempt accounted for approximately 10% of attempted CTO‐PCI during the study period 2 ; prior failed attempt was associated with a lower successful CTO revascularization rate, J‐CTO score ≥2, IVUS procedure, and prior failed attempt, were independent predictors for successful CTO revascularization; and 3 prior attempt had no significant effects on major procedural complication and MACE rates of subsequent CTO‐PCI, which was mainly accounted for by the TVR rate.

Percutaneous recanalization of CTO lesions remains more challenging despite remarkable progress in dedicated devices and interventionist expertise, with a high success rate of >85%. 11 , 12 Conversely, patients who undergo failed CTO‐PCI constitute a specific subset and should not be neglected. In our study, approximately 10% of the patients underwent prior failed attempt CTO‐PCI, mainly indicated by symptoms of angina or acute coronary syndrome, as described in a previous study. 13 Similar to all patients undergoing CTO‐PCI, for patients with previous CTO‐PCI failure, successful reattempt PCI of CTO is associated with improved clinical outcomes. 14 Therefore, percutaneous recanalization of CTOs is considered reasonable in patients with a prior failed CTO‐PCI.

In our study, prior‐failed‐attempt CTO‐PCI had a lower successful CTO revascularization rate than initial‐attempt CTO‐PCI. Compared with initial‐attempt CTO‐PCI, prior‐failed‐attempt CTO‐PCI appeared even harder, and more complex procedures had to be performed. Previous failure indicated a challenging reattempt CTO recanalization, manifested by a higher J‐CTO score in this subpopulation. In our study, patients who underwent prior‐failed‐attempt CTO‐PCI had a significantly higher proportion of ≥2 J‐CTO score than those who underwent initial‐attempt CTO‐PCI. As a widely used scoring system, the J‐CTO score is frequently used to predict the probability of successful guidewire crossing within 30 min, which reflects the difficulty of percutaneous recanalization of CTO lesions. 7 As one of the key parameters in the scoring system, prior failed attempt was given one point, and a J‐CTO score ≥2 was considered a more difficult lesion. Thus, the re‐attempted CTO lesions are more complex, and the prior‐failed‐attempt CTO‐PCI appears more challenging than the initial‐attempt CTO‐PCI. 15 Our findings validated the effectiveness of the J‐CTO score system and also demonstrated that J‐CTO score ≥2 and prior failed attempt were independent predictors for successful CTO revascularization, consistent with the results reported in previous studies. 7 , 16 Additionally, our study identified the determinative role of IVUS in predicting subsequent CTO‐PCI success. IVUS can be applied to determine the true lumen, help guide wire crossing, and optimize the PCI procedure, especially in heavily calcified CTO segments. 17

The accumulation of operating techniques and expertise in combination with the implementation of the hybrid algorithm in CTO‐PCI has resulted in a sustained improvement in the percutaneous recanalization of CTO lesions in recent years. 2 Accordingly, prior‐failed‐attempt CTO‐PCI inevitably requires complex procedures, including the retrograde approach, longer fluoroscopic time, and longer procedure duration. 15 , 18 In this study, more patients who underwent prior‐failed‐attempt CTO‐PCI underwent femoral artery access, and the retrograde approach was more frequently used in this group, with a trend toward higher contrast volume and longer fluoroscopy time. For most CTO lesions, the antegrade approach, including AWE and ADR, is often adopted as the first‐choice crossing strategy, and successful recanalization can be achieved in most situations. In some circumstances however, especially in prior‐failed‐attempt CTO‐PCI, a retrograde approach may be considered (including RWE and RDR); this approach can improve the procedure's success rate. 6 , 18 , 19 , 20 In addition, it has been reported that the use of dedicated CTO devices, such as the CrossBoss, or the Stingray catheter is associated with an increased successful CTO‐PCI rates. 11 , 21 However, during the study period, CrossBoss and the Stingray catheter were unavailable in our center.

The incidence of major procedural complications was comparable between patients who underwent prior‐failed‐attempt CTO‐PCI and initial‐attempt CTO‐PCI in our study, which is consistent with the latest report. 18 This implies that the use of more complex techniques and devices by experienced operators in re‐attempting CTO‐PCI does not necessarily translate to an increased incidence of adverse events. There was no significant effect of a prior attempt on the MACE rate of the subsequent CTO‐PCI in our study. There are several potential explanations for this lack of effect. First, despite the fact that aggressive techniques and dedicated dissection and reentry devices, such as the retrograde approach, the CrossBoss, or the Stingray catheter, were more frequently used in the reattempt CTO‐PCI; the procedures for the patients with prior‐failed‐attempt CTO‐PCI were often well prepared and performed by experienced operators. Timely termination of the procedure is important in cases of major procedural complications. Second, although lower optimal success rates were observed in the prior‐failed‐attempt group than in the initial‐attempt group, during the reattempt procedure, the so‐called subintimal plaque modification or “investment” procedures might predispose to subsequent success with a favorable outcome. 14 , 22 Third, even if successful CTO revascularization in the initial attempt could be achieved more often, a trend of a higher TVR rate, mainly resulting from stent restenosis, might contribute to an unsatisfactory outcome.

4.1 Study limitations

Our study has some limitations, owing to a few reasons. This was a small observational study conducted at a single center, and the decision to perform CTO‐PCI was made at the discretion of the interventionist, which would result in selection bias. Furthermore, the number of patients in the prior‐failed‐attempt group was relatively small, and the two groups were not balanced in size. Although we performed a propensity score‐matched analysis to correct for these potential confounding factors, it was difficult to adjust for all unmeasured variables. Due to the gradual accumulation of expertise in CTO‐PCI across the study period, CTO intervention techniques have undergone a sustained improvement. Thus, the results of our study should be interpreted with caution. In addition to these, the success rate of CTO‐PCI in our study was lower than those reported in the literature (76% vs. 83%). 13 , 23 Experience with percutaneous treatment of CTO lesions is more variable in diverse centers; therefore, the results of this study should only be interpreted in certain settings. Nonetheless, our results are representative of real‐world practice. Third, angiographic evaluation during follow‐up was not mandatory; only patients presenting with recurrence of angina and/or new emerging ischemic evidence underwent repeat angiography, followed by subsequent TVR when indicated. This might have resulted in an underestimation of the TVR rate driven by target vessel failure.

5 CONCLUSIONS

Patients who undergo prior‐failed‐attempt CTO‐PCI constitute a noticeable subset of all patients undergoing CTO‐PCI. Prior‐failed‐attempt CTO‐PCI appears even harder, which is associated with a lower successful CTO revascularization rate. Prior failed attempt, J‐CTO score ≥2, and IVUS procedure are the determining factors for predicting successful CTO revascularization. Despite the lower optimal success rate in the patients with a prior failed attempt, no significantly unfavorable outcomes in terms of major procedural complications and MACE are observed. Special considerations should be taken regarding the strategy and algorithm of recanalization of CTO in future practice; these include the utilization of modern imaging techniques, such as coronary computed tomography angiogram before re‐attempt procedures and IVUS use during the procedure.

AUTHOR CONTRIBUTIONS

H.P.Z. and N.X.Z.: Study conception and design. H.P.Z., X.P., L.L., and H.A.: Acquisition of data. N.X.Z., X.P., H.P.Z., and H.A.: Analysis and interpretation of data (e.g., statistical and computational analyses). N.X.Z. and H.P.Z.: Writing, review, and/or revision of the manuscript. H.P.Z.: Study supervision.

FUNDING INFORMATION

This study was supported by the National High Level Hospital Clinical Research Funding (BJ‐2018‐201).

CONFLICT OF INTEREST STATEMENT

The authors declare that they have no competing interests.

ETHICS STATEMENT

This study was approved by the institutional Ethics Committee (approval no. 2019BJYYEC‐021‐02).

CONSENT

All patients provided informed consent to participate in this study and underwent the intervention procedure.

DATA AVAILABILITY STATEMENT

The datasets analyzed in the current study are available from the corresponding author upon request.
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