Gender Differences in Long-Term Outcomes of Medical Therapy and Successful Percutaneous Coronary Intervention for Coronary Chronic Total Occlusions

Guo, Lei; Lv, Haichen; Zhong, Lei; Wu, Jian; Ding, Huaiyu; Xu, Jiaying; Huang, Rongchong

doi:https://doi.org/10.1155/2019/2017958

Journal of Interventional Cardiology

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Abstract Introduction Methods Results Discussion Conclusions Data Availability Conflicts of Interest Authors’ Contributions Acknowledgments References Copyright Related Articles

Research Article | Open Access

Volume 2019 | Article ID 2017958 | https://doi.org/10.1155/2019/2017958

Gender Differences in Long-Term Outcomes of Medical Therapy and Successful Percutaneous Coronary Intervention for Coronary Chronic Total Occlusions

Lei Guo,¹Haichen Lv,¹Lei Zhong,¹Jian Wu,¹Huaiyu Ding,¹Jiaying Xu,¹and Rongchong Huang¹

Academic Editor: Thach N. Nguyen

Received01 Jun 2019

Revised21 Jul 2019

Accepted22 Aug 2019

Published10 Sept 2019

Abstract

Background. There is a paucity of information about the gender differences in clinical outcomes of successful percutaneous coronary intervention (PCI) compared with medical therapy (MT) in patients with coronary chronic total occlusions (CTOs). Objectives. We aimed to investigate the impact of gender on long-term clinical outcomes associated with successful CTO-PCI versus MT in patients with CTOs. Methods. Between January 2007 and December 2016, a total of 1702 patients with ≥1 CTO were enrolled. After exclusion, 1294 patients with 1520 CTOs were analyzed and were divided into the female group (n = 304, 23.5%) and the male group (n = 990, 76.5%). The patients in the female or male group were assigned to a MT group or successful CTO-PCI group according to the treatment strategy. In the female group, they were divided into two groups: 177 patients in the MT group and 127 patients in the successful CTO-PCI group. In the male group, they were divided into two groups: 623 patients in the MT group and 367 patients in the successful CTO-PCI group. The primary outcome was cardiac death. The secondary outcome was major adverse cardiac event (MACE). Results. The median overall follow-up duration was 3.6 (IQR, 2.1–5.0) years, there were no significant differences between the MT and successful CTO-PCI groups with respect to the prevalence of cardiac death (MT vs. successful PCI: 6.8% vs. 3.9%, ) and MACE (20.9% vs. 21.3%, ) in female patients. In the male group, the occurrence of cardiac death (MT vs. successful PCI: 6.6% vs. 3.8%, ) was similar between the two groups. The MACE rate (30.0% vs. 18.5%, ) was significantly higher in the MT group. Heart failure (hazard ratio 3.40, 95% confidence interval 1.23–9.40, ) was an independent predictor of cardiac death in female patients. Conclusions. Successful CTO-PCI was not associated with reduced risk of cardiac death compared with medical therapy alone in both female and male patients. However, men have a significant reduction in MACE rate after successful CTO-PCI. Aggressive CTO-PCI should be considered carefully among female patients.

1. Introduction

Gender differences have long been known to exist in the presentation and outcome of coronary artery disease (CAD). Multiple studies indicate that female patients are less likely than male to be referred for invasive coronary angiography and to undergo revascularization, despite almost the same prevalence of coronary disease [1, 2].

Chronic total occlusions (CTOs) represent an important and unique subgroup of coronary lesions and have been identified in up to 18% of all patients referred for diagnostic angiography [3, 4]. Most studies reported that successful CTO percutaneous coronary intervention (PCI) is associated with symptomatic relief of angina, improvement in left ventricular function, quality of life, and a reduction in mortality compared with failed CTO-PCI [5–7]. However, only approximately 10%–20.7% of CTOs are currently undergoing attempted CTO-PCI [3, 8], mainly because CTO-PCI procedures may be with relatively lower success rate, a higher risk of complication, and higher expense when compared with non-CTO elective PCI [9, 10]. Indeed, a substantial portion of CTO patients are treated with medical therapy (MT) alone instead of PCI [11, 12].

Female patients with CTOs have a greater incidence of comorbidities and a higher risk of intraoperative and postoperative complications compared with male patients [13–15]. Therefore, clinicians are more likely to treat these female patients who have CTOs with MT alone, and a previous study also reported female patients have the lowest rate of revascularization [16]. However, current CTO studies are typically comprised of less than 20% female patients, which is in accordance with the overall low inclusion of women in cardiovascular registries and randomized trials relevant to CTO [3, 13, 14], and there is relative paucity of information about the gender differences in clinical outcomes of successful CTO-PCI compared with MT for CTO patients. Moreover, most studies only focused on the outcomes between successful and failed CTO-PCI, the patients who undergo MT alone and did not undergo a CTO-PCI attempt were rarely considered previously [17]. Therefore, this study aimed to investigate the impact of gender on long-term clinical outcomes associated with successful CTO-PCI versus MT in patients with CTOs.

2. Methods

2.1. Study Population

The present study was a retrospective observational study. A total of 16224 patients who underwent diagnostic coronary angiography from January 2007 to December 2016 were included at the First Affiliated Hospital of Dalian Medical University (Dalian, China) [18]. Of these patients, 1702 had at least one CTO. 47 patients who underwent previous CABG and presented with acute myocardial infarction within 48 h were excluded. Among the 1655 patients, those who underwent CABG and failed CTO-PCI were excluded. Thus, 1294 patients with at least one CTO were included for analysis (Figure 1). Patients were grouped into the female group and the male group. The patients in the female group or male group were assigned to a MT group or successful CTO-PCI group according to the treatment strategy. Initial PCI or MT was selected according to the presence of symptoms, high comorbidity or high risk for revascularization, the suitability of the target distal vessel for revascularization (diameter > 2.5 mm), and patients’ economic burden [18]. In asymptomatic patients who did not have viability data available or in subjects with proved absence of viability, MT was strongly preferred. In symptomatic patients, even without information on viability or in asymptomatic patients with viability, PCI was preferred. The decision to perform PCI for CTO patients was also dependent on several factors, including LV function, the extent of other coronary artery disease, CTO location, and technical difficulty. However, several other factors, including patient preference and their family members’ willing and their economic burden and doctors’ assessment, also influenced the final decision of the management strategy. The cost of CTO-PCI was at least thirty to fifty thousand yuan (nearly 4.3 to 7.2 thousand dollars) in our hospital and was relatively high for some families. The decision to perform CTO-PCI was at the discretion of the interventional cardiologists and the patients and their family members’. The baseline clinical and procedural characteristics were collected from the dedicated database and medical records. Clinical end points were obtained from clinical hospital records, visits, or telephone contacts with living patients or family members. The institutional review board approved the present study.

2.2. Treatment Strategy

MT comprised the use of antiplatelet medication, aggressive lipid-lowering therapy, blockade of the rennin-angiotensin system, β-blockers, and nitrates. Coronary interventions were performed according to standard techniques. Beginning at least 24 hours before the procedure, all patients were prescribed a loading dose of aspirin (300 mg) and/or clopidogrel (300 mg) before PCI. For patients with more than one CTO, only one CTO vessel was targeted and no further attempt was made during the study period. After the procedure, a dual antiplatelet therapy with aspirin (100 mg/day) and clopidogrel (75 mg/day) was prescribed at least 12 months. All patients underwent two-dimensional echocardiography. In presence of normal wall motion in the territory supplied by the CTO artery, no further viability testing was performed.

2.3. Definitions and Study Outcomes

A “CTO lesion” was defined as an obstruction of a native coronary artery with a thrombolysis in myocardial infarction (TIMI) flow grade of 0 on angiography and estimated duration of >3 months [5]. A successful PCI was defined as a final residual stenosis <20%, with a TIMI grade flow ≥2 after stent implantation. The primary endpoint was the incidence of cardiac death during follow-up after PCI. The secondary endpoint was major adverse cardiac event (MACE), defined as the composite of cardiac death, myocardial infarction (MI), and target vessel revascularization (TVR). Cardiac death was defined as a death due to cardiovascular cause in absence of established cardiovascular etiology. MI was defined as an elevation of creatine kinase-MB fraction or troponin-T/troponin-I greater than the upper limit of normal with concomitant ischemic symptoms or electrocardiographic findings indicative of ischemia. TVR was defined as repeat revascularization of a CTO vessel [18, 19].

2.4. Statistical Analysis

Data are presented as percentages and mean ± standard or median (IQR) as appropriate. Categorical data were tested with the chi-square test or Fisher’s exact test. Continuous variables were compared using the Student’s t-test or Mann–Whitney U test. Event-free survival was calculated using the Kaplan–Meier method and compared with the log-rank test. Cox proportional hazards methods were used to estimate the independent effect of multiple independent variables on the risk of cardiac death. Univariate variables with values < 0.05 were included in the multivariate model. All tests were two-tailed. A value of <0.05 was considered significant. SPSS version 24 software (IBM, New York, USA) was used for statistical analysis.

3. Results

3.1. Baseline Characteristics

After exclusion, a total of 1294 patients with 1520 CTOs were enrolled in this study. The female group included 304 (23.5%) patients, and the male group included 990 (76.5%) patients. In the female group, they were divided into two groups: 177 in the MT group and 127 patients in the successful PCI group. In the male group, they were divided into two groups: 623 in the MT group and 367 patients in the successful PCI group (Figure 1).

Table 1 shows the baseline, angiographic, and procedural characteristics and in-hospital outcome of the enrolled patients. Compared to male patients, female patients were older and had more frequently hypertension, diabetes mellitus, dyslipidemia, and chronic kidney disease (CKD) and were less likely to have smokers, previous MI, and previous PCI. Women presented with less lesion bending (>45°) and other angiographic and procedural characteristics were similar between the two groups. As for procedural complications and in-hospital outcomes, there were no significant differences in the prevalence of coronary dissection, coronary perforation, and in-hospital death.

Table 2 shows the baseline clinical, angiographic, and procedural characteristics of female and male patients in the medical therapy and successful PCI groups. In the female group, patients in the MT group were older and more often had previous MI, CKD, taking clopidogrel. Branched CTO, CTO of left circumflex coronary artery (LCX), blunt stump, high J-CTO score, and SYNTAX score were presented more frequently in patients in the MT group compared with patients in the successful PCI group. In the male group, as compared with patients referred for successful PCI, those referred for MT were older and more likely to have previous MI, CKD, heart failure, branched CTO, CTO of LCX, blunt stump, and calcification, with high J-CTO score and SYNTAX score, but low left ventricular ejection fraction (LVEF), and were less likely to have CTO of the left ascending coronary artery.

3.2. Clinical Outcomes

The median overall follow-up duration was 3.6 (IQR, 2.1–5.0) years. In the female group, no significant differences were observed between the MT and successful CTO-PCI groups in terms of cardiac death (MT vs. successful PCI: 6.8% vs. 3.9%, ) and MACE (20.9% vs. 21.3%, ). In the male group, the occurrence of cardiac death (MT vs. successful PCI: 6.6% vs. 3.8%, ) was comparable between the two groups. The MACE rate (30.0% vs. 18.5%, ) was significantly higher in MT group (Table 3) (Figure 2).

(a)

(b)

There was no significant interaction between gender and treatment strategy in terms of cardiovascular mortality (). The cardiovascular survival benefit after successful PCI was similar in female and male patients (Figure 3).

Table 4 shows independent predictors of cardiac death in female and male patients. After multivariate analysis, heart failure (hazard ratio [HR] 3.40, 95% confidence interval [CI] 1.23–9.40, ) was associated with a higher cardiac death rate in female patients; age (per-year increment) (HR 1.07, 95% CI 1.04–1.11, ) and calcification (HR 3.57, 95% CI 2.05–6.25, ) were independent predictors of cardiac death in male patients.

4. Discussion

We compared the long-term clinical outcomes of medical therapy versus successful CTO-PCI in female and male patients with CTOs. The main findings of our study are as follows: (1) only 23.5% of the patients with CTOs were female; (2) female patients were significantly older and had more frequent hypertension, diabetes mellitus, dyslipidemia, and CKD; (3) successful CTO-PCI was not associated with a reduced risk of cardiovascular mortality or MACE as compared with MT alone in female patients with CTOs; (4) successful CTO-PCI was associated with a lower rate of MACE as compared with MT alone in male patients with CTOs. To the best of our knowledge, this is one of the largest studies to compare the impact of gender on long-term clinical outcomes associated with successful CTO-PCI versus MT in unselected CTO patients.

Only a small minority of patients (23.5%) in the current study were female which was consistent with previous studies [13, 15]. In this high-risk patient cohort with advanced CAD, female patients were on average older than male patients when they first undergo invasive cardiovascular procedures, presumably due to the potentiating protective effects of oestrogen against coronary atherosclerosis until menopause, so the CAD process may be delayed. Furthermore, female patients were more frequently presented with hypertension, diabetes mellitus, dyslipidemia, and CKD which increase the risks associated with PCI, and these multiple comorbidities probably explain the low percentage of women recorded in our study as well as in other studies [7, 16, 19, 20]. In addition, female patients have more intraoperative and postoperative complications, including coronary perforation, bleeding, and contrast-induced nephropathy [15, 21]. Therefore, some interventional cardiologists were less often to perform CTO-PCI in female patients [16].

According to the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial, which conducted in patients with stable CAD, PCI was not associated with reducing the risk of death or other MACE when added to optimal medical therapy [22]. Similarly, our study also suggested that successful CTO-PCI did not reduce the prevalence of cardiac death in patients with CTOs probably because a large part of our cohort had stable coronary disease, and a similar study population was also included in the COURAGE trial.

Several studies had compared the clinical outcomes of successful CTO-PCI with failed PCI among female patients with CTOs, and had mainly shown a better outcome with regard to successful PCI [13, 23]. In our study, patients in the MT group did not undergo a CTO-PCI attempt, a population that has not been considered previously [17, 18]. Accordingly, in contrast to previous studies, our study better reflects the overall risk and clinical significance of PCI compared with medical therapy alone in patients with coronary CTOs [18].

Until now, due to the relative paucity of literature regarding sex-related differences in CTO outcomes, clinical outcome of CTO-PCI in this population is unknown. In the present study, we found that successful PCI is not associated with reduced prevalence of cardiac death, as compared with MT alone among female and male patients with CTOs, consistent with the finding of previous studies [1, 2]. Our previous study also suggested that successful CTO-PCI did not reduce cardiac death or MACE compared with MT [11, 24]. Furthermore, there was also no significant reduction in MACE rate after successful CTO-PCI in female patients. Those female patients who had medical therapy alone tended to be older and more often had CKD, CTO of left LCX, blunt stump, high J-CTO score, and SYNTAX score and were also unsuitable for PCI. These findings suggest that, considering multiple comorbidities, the high prevalence of intraoperative and postoperative complications and prognosis, as well as high expense, aggressive CTO-PCI should be considered carefully in female patients with coronary CTOs.

Interestingly, the present study showed only a reduced MACE after successful CTO-PCI in male patients, which was in accordance with previous one [25]. One possible explanation may be the relatively small sample size of the female cohort in this study. Moreover, a previous study from the multinational CTO registry and meta-analysis had turned out that gender was not independently associated with adverse outcomes [26, 27].

Several limitations should be taken into consideration. First, this was not a randomized trial and selection bias could have occurred. Second, a relatively low number of women were included. Third, the amount of viable myocardium was not routinely evaluated, which may affect the results. The expense of the test was relatively high for most families, and many CTO patients refused to accept the test, even after doctors’ explanation. However, all patients in this study underwent two-dimensional echocardiography which was relatively cheap and acceptable for most patients and we used it to evaluate LV function. In presence of normal wall motion in the territory subtended by the CTO artery, no further viability testing was performed. Fourth, since this was a retrospective cohort study, routine collection of postprocedural cardiac enzymes was not performed in every patient from the study beginning, only in the case that patients suffered intraoperative myocardial or vascular injury or were present with sustained angina after operation. However, postoperative electrocardiogram was performed in every patient. Randomized controlled trials are needed to investigate clinical outcomes of medical therapy and successful percutaneous coronary intervention in both female and male patients.

5. Conclusions

A minority of CTO patients (23.5%) were women. Successful CTO-PCI was not associated with reduced the risk of cardiac death compared with medical therapy alone in both female and male patients. However, successful CTO-PCI reduced the rate of MACE in male patients. Aggressive CTO-PCI should be considered carefully among female patients. Larger randomized controlled trials are needed to support these findings.

Data Availability

The data used to support the findings of this study are available from the corresponding author upon request.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

Authors’ Contributions

Lei Guo and Haichen Lv contributed equally to this study.

Acknowledgments

The authors acknowledge and thank Ying Liu and Kun Chen for their invaluable assistance. This study was supported by the China Cardiovascular Disease Alliance VG Youth Fund Project (no. 2017-CCA-VG-046), Beijing United Heart Foundation (no. BJUHFCSOARF201801-02), and Beijing Lisheng Cardiovascular Health Foundation (no. LHJJ20158521).

References

P. G. Steg, N. Greenlaw, J.-C. Tardif et al., “Women and men with stable coronary artery disease have similar clinical outcomes: insights from the international prospective CLARIFY registry,” European Heart Journal, vol. 33, no. 22, pp. 2831–2840, 2012.
View at: Publisher Site | Google Scholar
L. J. Shaw, R. E. Shaw, C. N. B. Merz et al., “Impact of ethnicity and gender differences on angiographic coronary artery disease prevalence and in-hospital mortality in the American college of cardiology-national cardiovascular data registry,” Circulation, vol. 117, no. 14, pp. 1787–1801, 2008.
View at: Publisher Site | Google Scholar
P. Fefer, M. L. Knudtson, A. N. Cheema et al., “Current perspectives on coronary chronic total occlusions the Canadian multicenter chronic total occlusions registry,” Journal of the American College of Cardiology, vol. 59, no. 11, pp. 991–997, 2012.
View at: Publisher Site | Google Scholar
J. A. Grantham, S. P. Marso, J. Spertus, J. House, D. R. Holmes, and B. D. Rutherford, “Chronic total occlusion angioplasty in the United States,” JACC: Cardiovascular Interventions, vol. 2, no. 6, pp. 479–486, 2009.
View at: Publisher Site | Google Scholar
G. Sianos, G. S. Werner, A. R. Galassi et al., “Recanalisation of chronic total coronary occlusions: 2012 consensus document from the EuroCTO club,” EuroIntervention, vol. 8, no. 1, pp. 139–145, 2012.
View at: Publisher Site | Google Scholar
P. Sirnes, Y. Myreng, P. Mølstad, V. Bonarjee, and S. Golf, “Improvement in left ventricular ejection fraction and wall motion after successful recanalization of chronic coronary occlusions,” European Heart Journal, vol. 19, no. 2, pp. 273–281, 1998.
View at: Publisher Site | Google Scholar
S. George, J. Cockburn, T. C. Clayton et al., “Long-term follow-up of elective chronic total coronary occlusion angioplasty analysis from the UK central cardiac audit database,” Journal of the American College of Cardiology, vol. 64, no. 3, pp. 235–243, 2014.
View at: Publisher Site | Google Scholar
A. Ladwiniec, V. Allgar, S. Thackray, F. Alamgir, and A. Hoye, “Medical therapy, percutaneous coronary intervention and prognosis in patients with chronic total occlusions,” Heart, vol. 101, no. 23, pp. 1907–1914, 2015.
View at: Publisher Site | Google Scholar
S. Rathore, H. Matsuo, M. Terashima et al., “Procedural and in-hospital outcomes after percutaneous coronary intervention for chronic total occlusions of coronary arteries 2002 to 2008 impact of novel guidewire techniques,” JACC: Cardiovascular Interventions, vol. 2, no. 6, pp. 489–497, 2009.
View at: Publisher Site | Google Scholar
H. Gada, P. L. Whitlow, and T. H. Marwick, “Establishing the cost-effectiveness of percutaneous coronary intervention for chronic total occlusion in stable angina: a decision-analytic model,” Heart, vol. 98, no. 24, pp. 1790–1797, 2012.
View at: Publisher Site | Google Scholar
L. Guo, L. Zhong, K. Chen, J. Wu, and R.-C. Huang, “Long-term clinical outcomes of optimal medical therapy vs. successful percutaneous coronary intervention for patients with coronary chronic total occlusions,” Hellenic Journal of Cardiology, vol. 59, no. 5, pp. 281–287, 2018.
View at: Publisher Site | Google Scholar
S. D. Tomasello, M. Boukhris, S. Giubilato et al., “Management strategies in patients affected by chronic total occlusions: results from the Italian registry of chronic total occlusions,” European Heart Journal, vol. 36, no. 45, pp. 3189–3198, 2015.
View at: Publisher Site | Google Scholar
B. E. Stähli, C. Gebhard, M. Gick et al., “Comparison of outcomes in men versus women after percutaneous coronary intervention for chronic total occlusion,” The American Journal of Cardiology, vol. 119, no. 12, pp. 1931–1936, 2017.
View at: Publisher Site | Google Scholar
B. E. Claessen, A. Chieffo, G. D. Dangas et al., “Gender differences in long-term clinical outcomes after percutaneous coronary intervention of chronic total occlusions,” The Journal of Invasive Cardiology, vol. 24, no. 10, pp. 484–488, 2012.
View at: Google Scholar
V. Sharma, W. Wilson, W. Smith et al., “Comparison of characteristics and complications in men versus women undergoing chronic total occlusion percutaneous intervention,” The American Journal of Cardiology, vol. 119, no. 4, pp. 535–541, 2017.
View at: Publisher Site | Google Scholar
R. Wolff, P. Fefer, M. L. Knudtson et al., “Gender differences in the prevalence and treatment of coronary chronic total occlusions,” Catheterization and Cardiovascular Interventions, vol. 87, no. 6, pp. 1063–1070, 2016.
View at: Publisher Site | Google Scholar
C. Godino, G. Bassanelli, F. I. Economou et al., “Predictors of cardiac death in patients with coronary chronic total occlusion not revascularized by PCI,” International Journal of Cardiology, vol. 168, no. 2, pp. 1402–1409, 2013.
View at: Publisher Site | Google Scholar
L. Guo, J. Wu, L. Zhong et al., “Two-year clinical outcomes of medical therapy vs. revascularization for patients with coronary chronic total occlusion,” Hellenic Journal of Cardiology, 2019.
View at: Publisher Site | Google Scholar
D. E. Cutlip, S. Windecker, R. Mehran et al., “Clinical end points in coronary stent trials a case for standardized definitions,” Circulation, vol. 115, no. 17, pp. 2344–2351, 2007.
View at: Publisher Site | Google Scholar
A. J. Saltzman, G. W. Stone, B. E. Claessen et al., “Long-term impact of chronic kidney disease in patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention the horizons-ami (harmonizing outcomes with revascularization and stents in acute myocardial infarction) trial,” JACC: Cardiovascular Interventions, vol. 4, no. 9, pp. 1011–1019, 2011.
View at: Publisher Site | Google Scholar
S. V. Rao, C. N. Hess, B. Barham et al., “A registry-based randomized trial comparing radial and femoral approaches in women undergoing percutaneous coronary intervention: the SAFE-PCI for women (study of access site for enhancement of PCI for women) trial,” JACC: Cardiovascular Interventions, vol. 7, no. 8, pp. 857–867, 2014.
View at: Publisher Site | Google Scholar
W. E. Boden, R. A. O’Rourke, K. K. Teo et al., “Optimal medical therapy with or without PCI for stable coronary disease,” New England Journal of Medicine, vol. 356, no. 15, pp. 1503–1516, 2007.
View at: Publisher Site | Google Scholar
M. Akodad, M. Spaziano, C. J. Garcia-Alonso et al., “Is sex associated with adverse outcomes after percutaneous coronary intervention for CTO?” International Journal of Cardiology, vol. 288, pp. 29–33, 2019.
View at: Publisher Site | Google Scholar
L. Guo, S. F. Zhang, J. Wu et al., “Successful recanalisation of coronary chronic total occlusions is not associated with improved cardiovascular survival compared with initial medical therapy,” Scandinavian Cardiovascular Journal, 2019.
View at: Publisher Site | Google Scholar
A. Toma, B. E. Stähli, M. Gick et al., “Temporal changes in outcomes of women and men undergoing percutaneous coronary intervention for chronic total occlusion: 2005–2013,” Clinical Research in Cardiology, vol. 107, no. 6, pp. 449–459, 2018.
View at: Publisher Site | Google Scholar
R. Mehran, B. E. Claessen, C. Godino et al., “Long-term outcome of percutaneous coronary intervention for chronic total occlusions,” JACC: Cardiovascular Interventions, vol. 4, no. 9, pp. 952–961, 2011.
View at: Publisher Site | Google Scholar
P. Rattanawong, T. Riangwiwat, W. Vutthikraivit et al., “Gender difference and outcome after percutaneous intervention in patients with chronic total occlusion: a systemmatic and meta-analysis,” Journal of the American College of Cardiology, vol. 71, no. 11, p. 1057, 2018.
View at: Publisher Site | Google Scholar

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Copyright © 2019 Lei Guo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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