Methods

The Florence CTO percutaneous coronary intervention (PCI) is a prospective, single-center registry started in 2003 that includes consecutive patients treated with drug-eluting stent-supported PCI for CTOs. From the database, we identified all patients who had received multiple EESs (either XIENCE V, Abbott Vascular, Santa Clara, California or PROMUS, Boston Scientific, Natick, Massachusetts) or PESs (either Taxus Express or Taxus Liberté, Boston Scientific) implantation for a total stent length of ≥40 mm. CTO was defined as a coronary obstruction with Thrombolysis In Myocardial Infarction flow grade 0 and an estimated duration of >3 months. The duration of the occlusion was determined by the interval from the last episode of acute coronary syndrome or, in patients without a history of acute coronary syndrome, from the first episode of effort angina consistent with the location of the occlusion, as indicated by stress echocardiography or scintigraphy, or by previous coronary angiography. In patients without a history of angina who were admitted for acute coronary syndrome or ST-segment elevation acute myocardial infarction with a definite identification of the culprit vessel, associated total occlusion of a nonculprit vessel was considered chronic occlusion if angiographic evidence was found of filling of the vessel through collaterals. The indication for percutaneous treatment of the CTO was the demonstration of viable myocardium in the territory of the occluded vessel by echocardiographic or scintigraphic provocative tests. No CTO angiographic characteristic was considered an absolute contraindication to a PCI attempt. Thus, patients with long occlusions, extensive calcification, bridging collaterals, a nontapered stump, or a side branch at the occlusion site were included. The occlusion length was assessed from the beginning of the occlusion to the distal anterograde or retrograde vessel filling from the bridge collaterals or collaterals provided by a coronary artery other than the CTO vessel and using simultaneous contrast medium injection in both right and left coronary arteries. All treatment of the occlusions was attempted using the anterograde or retrograde approach and dedicated coronary wires (hydrophilic and nonhydrophilic) and devices. The stent type used was at discretion of the operator. Standard stent implantation techniques, including minimum overlap between stents and routine postdilation using final high balloon pressure (≥16 atm), were used. All patients were pretreated with aspirin (300 mg/day) and clopidogrel (loading dose 600 mg). Aspirin (300 mg/day) was continued indefinitely, and clopidogrel (75 mg/day) for ≥12 months. Other drugs such angiotensin-converting enzyme inhibitors, β blockers, and statins were routinely prescribed according to the international guidelines.

All patients had scheduled clinical and electrocardiographic examinations at 6 months and at 1 and 2 years. All other possible information derived from hospital readmission records or by the referring physician, relatives, or municipality live registries were entered into a prospective database.

All patients gave written informed consent to data collection.

All eligible patients with successful PCI-treated CTOs were scheduled for angiographic follow-up at 6 to 9 months. Unscheduled angiography was allowed on the basis of clinical indications. Angiographic parameters were assessed using an automated edge-contour-detection computer analysis system (Innova 2100IQ, General Electric Healthcare Technologies, Little Chalfont, Buckinghamshire, United Kingdom).

The primary end point of the present study was angiographic in-segment restenosis, defined as >50% luminal narrowing at the segment site, including the stent and 5 mm proximal and distal to the stent edges of the target vessel, on the follow-up angiogram. The secondary end point was the 9-month composite of major adverse cardiovascular events (MACE), including cardiovascular death, myocardial infarction, and target vessel revascularization. All deaths were considered cardiac deaths, unless otherwise documented. Non–Q-wave myocardial infarction was defined as an increase in creatine kinase-MB fraction of 3 times the upper limit of normal or, for patients with elevated values on admission, as a re-elevation of the creatine kinase-MB values. The creatine kinase-MB fraction was routinely assessed 12 hours after PCI in all patients or ≥3 times every 6 hours in patients with recurrent chest pain. A Q-wave myocardial infarction was defined as a new Q wave in ≥2 contiguous leads, in addition to creatine kinase-MB elevation. Target vessel revascularization was defined as a repeat percutaneous or surgical revascularization procedure of the CTO vessel. The other clinical event collected was stent thrombosis, defined according to the Academic Research Consortium criteria.

From the results of a previous study, we assumed a restenosis rate and MACE rate with PESs of 30% and 24%, respectively, and a 50% reduction in both end points with EESs. To achieve a statistical power >80%, a sample size of ≥125 patients for each group was needed, considering an undeterminable primary end point in 20% of patients and an overall experimental type I error of 0.05.

Discrete data are summarized as frequencies, and continuous data as the mean ± SD or median and interquartile range. The chi-square test or Fisher’s exact test was used for comparison of categorical variables. Student’s t test or the Mann-Whitney U test, as appropriate, was used to test for differences among the continuous variables. Cumulative survival analyses were performed using the Kaplan-Meier method, and the difference between curves was assessed using the log-rank test.

The multivariate analysis to evaluate the independent contribution of clinical, angiographic, and procedural variables to in-segment restenosis was performed by forward stepwise logistic regression analysis. The following variables were tested: age, gender, hypertension, hypercholesterolemia (>200 mg/dl), current smoker, diabetes mellitus, previous myocardial infarction, left ventricular ejection fraction <40%, previous PCI, previous coronary surgery revascularization, acute coronary syndrome on admission, three-vessel disease, left anterior descending artery CTO vessel, CTO reference vessel <2.5 mm, CTO involving bifurcation, CTO with heavy calcification, drug-eluting stent type (EES or PES), CTO stent length, and complete coronary revascularization. A multivariate analysis using a forward stepwise Cox proportional hazards model was performed to evaluate the independent predictors of MACE. The odds ratio and hazards ratio and their 95% confidence intervals (CIs) were calculated.

All tests were 2-tailed. p Values <0.05 were considered significant. Analyses were performed using the Statistical Package for Social Sciences, version 11.5 (SPSS, Chicago, Illinois).

Results

From the database that included 840 CTO PCI procedures, we identified 258 patients who had received multiple EESs (n = 112) or PESs (n = 146), with a total stent length of ≥40 mm.

The study population had a mean age of 67.6 ± 10.7 years, most patients had a history of myocardial infarction, and 1/3 had diabetes mellitus. The 2 groups were similar in all baseline characteristics ( Table 1 ). The median lesion length was 48 mm in the EES group and 46 mm in the PES group (p = 0.793).

The procedural characteristics are summarized in Table 2 . No difference was found between the 2 groups in all procedural characteristics, except for the final postdilation inflation pressure and fluoroscopic time, which were greater in the EES group. The mean number of stents per patient was 2.7 in the EES group and 2.6 in the PES group. The mean stent length was nonsignificantly longer in the EES group than in the PES group (72 ± 26 mm in the EES group and 69 ± 23 mm in the PES group, p = 0.356). The large majority of patients in both groups underwent multivessel PCI and complete revascularization. The clinical and angiographic outcomes at 9 months are summarized in Table 3 .

Table 2

Procedural characteristics

Variable	PES Group (n = 146)	EES Group (n = 112)	p Value
Occlusion length (mm)
Mean ± SD	49 ± 18	50 ± 19	0.758
Median	46	48	0.793
Interquartile range	35–60	36.5–60
Reference chronic total occlusion vessel diameter (mm)	2.76 ± 0.44	2.74 ± 0.48	0.872
Chronic total occlusion diameter ≤2.5 mm	24 (16%)	22 (20%)	0.505
Chronic total occlusion stent implanted (n)	381	303	0.345
Mean no. of stents/patient	2.61	2.71
Chronic total occlusion stent length (mm)
Mean ± SD	69 ± 23	72 ± 26	0.356
Median	64	66	0.544
Interquartile range	49.5–84.5	51–90.5
Postpercutaneous coronary intervention minimum lesion diameter (mm)	2.85 ± 0.40	2.92 ± 0.37	0.201
Postdilation pressure (atm)			<0.001
Median	18	20
Interquartile range	16–20	18–22
Fluoroscopic time (minutes)			<0.001
Median	26	34.5
Interquartile range	18–36	22–50
Contrast material (ml)			0.951
Median	350	350
Interquartile range	250–450	220–500
Multivessel PCI	97 (66%)	79 (71%)	0.484
Completeness of revascularization	117 (80%)	97 (87)	0.171
Periprocedural complications
Q-wave myocardial infarction	0	0
Non–Q-wave myocardial infarction	3 (2%)	2 (2%)	0.876
Thrombolysis In Myocardial Infarction major bleeding	4 (3%)	5 (4%)	0.454
Contrast-induced nephropathy	6 (4%)	5 (4%)	0.889

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