Abstract
Objective
Limited data are available for the clinical outcomes after the recanalization of right coronary artery (RCA) chronic total occlusion (CTO). The study aims to assess the clinical outcomes in the antegrade flow of the distal branch after successful RCA CTO percutaneous coronary intervention (PCI).
Methods
Between January 2002 and December 2012, 538 patients who underwent RCA CTO PCI were enrolled. The clinical outcomes as myocardial infarction (MI), target vessel revascularization, cardiac death, major adverse cardiac events, and all-cause mortality, were compared to the antegrade flow of distal branch after successful RCA CTO PCI.
Results
The CTOs were located in proximal segments (57.6%), mid segments (27.5%) and distal segments (14.9%). The average Syntax score was 18.4 ± 9.6 and 47.8% patients had a Syntax score greater than 27.5. A total of 62.8% patients had final thrombolysis of myocardial infarction (TIMI)-3 flow of distal branch, 16.9% patients had final TIMI-3 flow of only one major branch, 11.3% patients had TIMI-1-2 flow, and 8.9% patients had no antegrade flow. The incidence of periprocedural MI was lower in both side branches were preserved (13.9% vs. 23.0% and 18.8%, p = 0.01). The clinical outcomes were similar between the groups with and without good antegrade flow of distal side branch. End stage renal disease (ESRD) and left ventricular ejection fraction (LVEF) <40% predicted three-year cardiac death.
Conclusions
There is no significant difference of clinical outcomes when distal side branches of RCA are recanalized successfully. ESRD and LVEF <40% were the predictors for three-year cardiac death.
Highlights
- •
There are reasons why the limit of the analysis of RCA CTO rather than LCA CTO was two-fold.
- •
First, the analysis’ major branch occlusion after RCA CTO PCI could help in decision making when only one major branch was recanalized without the other one.
- •
Second, the analysis could also help to distinguish whether the poor final flow of one major side branch impacts on the long-term survival outcomes.
1
Introduction
Percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) has become one of the most challenging procedures for interventional cardiologists in the recent era. The successful recanalization of CTO in patients with viable myocardium decreases the need for bypass surgery, reduces anginal symptoms, and associated with improved long-term survival . PCI devices and techniques for CTO have improved in the current era , and multiple pilot studies have reported excellent outcomes, especially with the use of drug-eluting stents and newly developed technique and devices . Our study compared the clinical outcomes between differently final antegrade TIMI flow after recanalization of RCA CTO PCI.
The differences between the treatment of CTOs in the three major coronary arteries have been compared in recent studies . CTOs in the RCA have angiographic characteristics that include significantly longer lesion length, increased angulation degree, more calcification and bridging collaterals, and relatively lower success rates . Another multicenter CTO PCI registry showed that the LCX was the least common target vessel and had a lower procedural success rate than lesions in the RCA and LAD . Long-term survivals after CTO PCI also have been analyzed based on the artery treated, and two pilot studies revealed that successful LAD CTO PCI and LCX CTO PCI both had survival benefits .
RCA CTO PCIs accounted for an estimated 30–50% of CTO PCI attempts in previous studies . The specific angiographic characteristic of the two major downstream side branches, the posterior descending artery (PDA) and the posterolateral branch (PLB), makes successful RCA CTO PCI more challenging. We are not aware of reported data that examine the patency of both PDA and PLB after successful RCA CTO PCI. The study aims to assess the clinical outcomes in the antegrade flow of the distal branch after successful RCA CTO PCI.
2
Methods
2.1
Patient enrollment and exclusion criteria
This retrospective study protocol was approved by the Institutional Review Board of Kaohsiung Chang Gung Memorial Hospital in Taiwan. CTO was defined as TIMI grade 0 flow for more than 3 months, with the presence of typical angina or reversible myocardial ischemia on a thallium stress study. During the period from January 2002 to December 2012, a total of 1688 CTO lesions received PCI: 36.0% were at RCA, PDA, and PLB; 0.7% were at left main; 45.7% were at LAD, diagonal branch; and 17.5% were at LCX and OM branch. A total of 538 consecutive patients who underwent PCI for RCA CTO of a native coronary artery were reviewed coronary angiography and charts.
Three groups were classified by the post-recanalization antegrade TIMI flow ( Fig. 1 ). Group A included the patients with both PDA and PLB TIMI-3 flow after PCI. Group B1 included the patients with only PDA or PLB TIMI-3 flow after PCI. Group B2 included the patients with both PDA and PLB TIMI-1-2 flow with or without collaterals. Group D included the patients with both PDA and PLB no flow with or without collaterals. Group A and group B1 was defined as successful groups, and group B2 and group C was defined as failure groups. The baseline demographics, angiographic characteristics, and procedural outcomes were compared between good antegrade flow of distal branches (group A) and only one or no good antegrade flow of distal branches (group B1 and group B2).
2.2
Definitions
The duration of occlusion was estimated by a history of angina, a history of myocardial infarction (MI) in the same territory, or previous angiography. The characteristics of each CTO lesion were defined according to the Syntax score and J-CTO score based on the complexity of the coronary artery disease. CTO lesion length was measured with three methods: from the proximal occlusion to the distal retrograde filling from contralateral collaterals, using a dual injection technique; from the start of the filling of the bridging collaterals to the distal vessel reconstruction; or from the length of the lesion visible after the guidewire crossing. The retrograde approach was defined as the introduction of the guide-wire into the collateral channels (CCs), which were connected to the target CTO vessel distal to the lesion. Retrograde success was achieved when the retrograde guide-wire successfully entered the distal portion of the CTO segment. Angiographic success was defined as a residual stenosis ≤30% by visual analysis in the presence of grade TIMI 3 flow. In addition, the distal wire position was documented to be in the true lumen by either a coronary angiogram or intravascular ultrasound (IVUS) examination.
MACE was defined as MI, TVR, and cardiac death.
2.3
Coronary angiogram, IVUS, Syntax score, and J-CTO score interpretation
All coronary angiograms and IVUS were independently interpreted by a cardiologist who was blinded to the procedure. The Syntax scores and J-CTO scores were sent to a blinded and independent core angiographic laboratory for analysis.
2.4
Medications and other interventional materials
Each patient was pretreated with aspirin and clopidogrel and received weight-adjusted heparin dosing to keep the activated clotting time (ACT) more than 250 s each hour. The guide-wires used included Ultimate Bros 3 g (Asahi, Japan), Miracle 3 g (Asahi, Japan), Miracle 6 g (Asahi, Japan), Miracle 9 g (Asahi, Japan), Conquest (Asahi, Japan), Conquest Pro (Asahi, Japan), and Gaia-1, 2, 3 (Asahi, Japan) called stiff-wires. The microcatheters included Transit catheters (Cordis, USA), Finecross catheters (Terumo, Japan), Corsair catheters (Asahi, Japan), and the Ryujin over-the-wire balloon (Terumo, Japan). The re-entry devices for antegrade dissection reentry (ADR) technique such as stingray balloon and wire were not available in our study.
2.5
One-year and three-year clinical outcome endpoints
The primary endpoints of MI, TVR, cardiac death, MACE and all-cause mortality were compared in the patients with or without a good antegrade flow of distal branches. All of the events were identified according to the Academic Research Consortium definitions .
2.6
Statistical analysis
Study variables were reported as the mean ± standard deviation for continuous variables and as percentages for categorical variables. The chi-square test was used for categorical variables, and Student’s t-test was used for continuous variables. Receiver operating characteristic (ROC) curves were used to determine the optimal values in terms of sensitivity and specificity. Event rates were estimated with Kaplan–Meier methods. Follow-up was censored at the date of last follow-up or at 3 years, whichever came first. Survival curves with all available follow-up data were constructed for time-to-event variables with Kaplan–Meier methodology and compared by log-rank test. Data on patients who were lost to follow-up were censored at the time of last contact. Univariate and multivariate Cox regression analysis was also performed for the identification of possible significant predictors for 3-year cardiovascular mortality. In our multivariate analysis, we included the analysis parameters that were found to exhibit significant differences in the univariate logistical analysis. A P level < 0.05 was considered statistically significant for all calculations. Statistics was performed using SPSS 22.0 (SPSS, Inc., Chicago, IL, USA).
2
Methods
2.1
Patient enrollment and exclusion criteria
This retrospective study protocol was approved by the Institutional Review Board of Kaohsiung Chang Gung Memorial Hospital in Taiwan. CTO was defined as TIMI grade 0 flow for more than 3 months, with the presence of typical angina or reversible myocardial ischemia on a thallium stress study. During the period from January 2002 to December 2012, a total of 1688 CTO lesions received PCI: 36.0% were at RCA, PDA, and PLB; 0.7% were at left main; 45.7% were at LAD, diagonal branch; and 17.5% were at LCX and OM branch. A total of 538 consecutive patients who underwent PCI for RCA CTO of a native coronary artery were reviewed coronary angiography and charts.
Three groups were classified by the post-recanalization antegrade TIMI flow ( Fig. 1 ). Group A included the patients with both PDA and PLB TIMI-3 flow after PCI. Group B1 included the patients with only PDA or PLB TIMI-3 flow after PCI. Group B2 included the patients with both PDA and PLB TIMI-1-2 flow with or without collaterals. Group D included the patients with both PDA and PLB no flow with or without collaterals. Group A and group B1 was defined as successful groups, and group B2 and group C was defined as failure groups. The baseline demographics, angiographic characteristics, and procedural outcomes were compared between good antegrade flow of distal branches (group A) and only one or no good antegrade flow of distal branches (group B1 and group B2).
2.2
Definitions
The duration of occlusion was estimated by a history of angina, a history of myocardial infarction (MI) in the same territory, or previous angiography. The characteristics of each CTO lesion were defined according to the Syntax score and J-CTO score based on the complexity of the coronary artery disease. CTO lesion length was measured with three methods: from the proximal occlusion to the distal retrograde filling from contralateral collaterals, using a dual injection technique; from the start of the filling of the bridging collaterals to the distal vessel reconstruction; or from the length of the lesion visible after the guidewire crossing. The retrograde approach was defined as the introduction of the guide-wire into the collateral channels (CCs), which were connected to the target CTO vessel distal to the lesion. Retrograde success was achieved when the retrograde guide-wire successfully entered the distal portion of the CTO segment. Angiographic success was defined as a residual stenosis ≤30% by visual analysis in the presence of grade TIMI 3 flow. In addition, the distal wire position was documented to be in the true lumen by either a coronary angiogram or intravascular ultrasound (IVUS) examination.
MACE was defined as MI, TVR, and cardiac death.
2.3
Coronary angiogram, IVUS, Syntax score, and J-CTO score interpretation
All coronary angiograms and IVUS were independently interpreted by a cardiologist who was blinded to the procedure. The Syntax scores and J-CTO scores were sent to a blinded and independent core angiographic laboratory for analysis.
2.4
Medications and other interventional materials
Each patient was pretreated with aspirin and clopidogrel and received weight-adjusted heparin dosing to keep the activated clotting time (ACT) more than 250 s each hour. The guide-wires used included Ultimate Bros 3 g (Asahi, Japan), Miracle 3 g (Asahi, Japan), Miracle 6 g (Asahi, Japan), Miracle 9 g (Asahi, Japan), Conquest (Asahi, Japan), Conquest Pro (Asahi, Japan), and Gaia-1, 2, 3 (Asahi, Japan) called stiff-wires. The microcatheters included Transit catheters (Cordis, USA), Finecross catheters (Terumo, Japan), Corsair catheters (Asahi, Japan), and the Ryujin over-the-wire balloon (Terumo, Japan). The re-entry devices for antegrade dissection reentry (ADR) technique such as stingray balloon and wire were not available in our study.
2.5
One-year and three-year clinical outcome endpoints
The primary endpoints of MI, TVR, cardiac death, MACE and all-cause mortality were compared in the patients with or without a good antegrade flow of distal branches. All of the events were identified according to the Academic Research Consortium definitions .
2.6
Statistical analysis
Study variables were reported as the mean ± standard deviation for continuous variables and as percentages for categorical variables. The chi-square test was used for categorical variables, and Student’s t-test was used for continuous variables. Receiver operating characteristic (ROC) curves were used to determine the optimal values in terms of sensitivity and specificity. Event rates were estimated with Kaplan–Meier methods. Follow-up was censored at the date of last follow-up or at 3 years, whichever came first. Survival curves with all available follow-up data were constructed for time-to-event variables with Kaplan–Meier methodology and compared by log-rank test. Data on patients who were lost to follow-up were censored at the time of last contact. Univariate and multivariate Cox regression analysis was also performed for the identification of possible significant predictors for 3-year cardiovascular mortality. In our multivariate analysis, we included the analysis parameters that were found to exhibit significant differences in the univariate logistical analysis. A P level < 0.05 was considered statistically significant for all calculations. Statistics was performed using SPSS 22.0 (SPSS, Inc., Chicago, IL, USA).
3
Results
3.1
Patient demographics
Table 1 includes the basic demographics of the study patients. A total of 538 RCA CTO patients were included. The average age of this study group was 64.3 ± 11.1 years old. Most patients (61.9%) had a clinical condition as unstable angina. Study group participants were mainly male (84.0%) and the incidence of hypertension was high (78.8%). The average of LVEF was 56.8 ± 14.3. Fifty-nine patients (13.2%) had an LVEF less than 40%. In the majority of cases, the evidence of ischemia was demonstrated via electrocardiography (48.3%) and thallium scan (26.4%). Electrocardiography showed Q-wave, greater than three segments of positive ischemic change in a thallium perfusion scan, and positive ischemic findings in treadmill tests, and cardiac computed tomography showed occluded evidence. CTO was combined with left main (LM) disease in 9.1% of the patients, and most of the patients (54.8%) had triple vessel coronary artery disease. There was no significant difference in baseline characteristics including LVEF between three groups. Group A had lower incidence of previous myocardial infarction (18.3% vs. 31.6% and 31.3%, p = 0.002).
| All | Group A | Group B | Group C | P value | |
|---|---|---|---|---|---|
| Number | 538 | 338 | 152 | 48 | |
| Demographics | |||||
| Age, yrs | 64.3 ± 11.1 | 62.35 ± 11.18 | 62.27 ± 11.02 | 64.77 ± 11.73 | 0.568 |
| Age > 75 | 66 (12.3) | 39 (11.5) | 19 (12.5) | 8 (16.7) | 0.595 |
| Male | 452 (84.0) | 282 (83.4) | 130 (85.5) | 40 (83.3) | 0.835 |
| Clinical condition | |||||
| Unstable angina | 333 (61.9) | 217 (64.2) | 85 (55.9) | 31 (64.6) | 0.348 |
| Risk factors | |||||
| Diabetes mellitus | 251 (46.7) | 157 (46.4) | 72 (47.4) | 22 (45.8) | 0.975 |
| Hypertension | 424 (78.8) | 262 (77.5) | 122 (80.3) | 40 (83.3) | 0.571 |
| Current smoker | 226 (42.0) | 139 (41.1) | 65 (42.8) | 22 (45.8) | 0.806 |
| Hyperlipidemia | 314 (58.4) | 195 (57.7) | 92 (60.5) | 27 (56.3) | 0.801 |
| Co-morbidity | |||||
| Previous MI | 125 (23.2) | 62 (18.3) a | 48 (31.6) b | 15 (31.3) b | 0.002 |
| Previous CABG | 30 (5.6) | 14 (4.1) | 12 (7.9) | 4 (8.3) | 0.168 |
| Previous stroke | 93 (17.3) | 52 (15.4) | 31 (20.4) | 10 (20.8) | 0.316 |
| PVD | 41 (7.6) | 28 (8.3) | 12 (7.9) | 1 (2.1) | 0.314 |
| ESRD | 45 (8.4) | 24 (7.1) | 15 (9.9) | 6 (12.5) | 0.329 |
| LVEF (%) | 56.8 ± 14.3 | 57.07 ± 14.14 | 56.57 ± 14.63 | 56.07 ± 14.29 | 0.867 |
| LVEF <40% | 59 (13.2) | 35 (12.9) | 20 (15.5) | 4 (8.9) | 0.509 |
| CAD vessel | |||||
| Left main disease | 49 (9.1) | 32 (9.5) | 14 (9.2) | 3 (6.3) | 0.768 |
| Triple vessel disease | 295 (54.8) | 187 (55.3) | 83 (54.6) | 25 (52.1) | 0.691 |
| Evidence of CTO | 0.209 | ||||
| Previous angiogram | 164 (30.5) | 107 (31.7) | 40 (26.3) | 17 (35.4) | |
| Non-invasive tests | 128 (23.8) | 86 (25.4) | 31 (20.4) | 11 (22.9) | |
| Date of specific cardiac event | 104 (19.3) | 68 (20.1) | 29 (19.1) | 7 (14.6) | |
| Unknown | 142 (26.4) | 77 (22.8) | 52 (34.2) | 13 (27.1) | |
| Non-invasive tests | |||||
| ECG evidence (Q-wave) | 260 (48.3) | 159 (47.0) | 91 (59.9) | 10 (20.8) | < 0.001 |
| Thallium scan (positive >3 segments) | 142 (26.4) | 87 (25.7) | 37 (24.3) | 18 (37.5) | 0.178 |
| Treadmill test (positive ischemic change) | 79 (14.7) | 55 (16.3) | 18 (11.8) | 6 (12.5) | 0.398 |
| Cardiac multislice CT (occluded evidence) | 26 (4.8) | 17 (5.0) | 5 (3.3) | 4 (8.3) | 0.351 |
| The average of Syntax score | 18.4 ± 9.6 | 17.55 ± 8.77 a | 19.43 ± 9.62 b | 21.44 ± 11.02 b | 0.009 |
| Syntax score | 0.070 | ||||
| ≦ 15.7 | 89 (16.5) | 173 (51.2) | 67 (44.7) | 16 (34.0) | |
| 15.7 ~ 27.5 | 192 (35.8) | 119 (35.2) | 54 (35.3) | 20 (40.4) | |
| > 27.5 | 257 (47.8) | 46 (13.6) | 31 (20.0) | 12 (25.5) | |
| J-CTO score | |||||
| ≧ 3 | 239 (44.4) | 135 (39.9) a | 80 (52.6) b | 26 (54.2) b | 0.013 |
| Follow-up duration (days) | 1286.4 ± 939.3 | 1327.7 ± 906.2 | 1278.7 ± 1073.5 | 1019.6 ± 635.7 | 0.103 |
| Loss follow-up number and rate | 48 (8.9) | 23 (6.8) | 18 (11.8) | 7 (14.6) | 0.078 |
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