Methods

From the Florence PCI registy, we identified consecutive patients treated by successful primary PCI (Thrombolysis In Myocardial Infarction [TIMI] grade 3 flow and residual infarct artery stenosis <30%), and with a coexisting non–infarct-related artery (IRA) CTO and evidence of viable myocardium in the territory supplied by the CTO vessel. Exclusion criterion was in-hospital death during the first week after primary PCI. Staged CTO-PCI attempt was performed up to 30 days from primary PCI. The study was approved by the institutional review committee, and all patients gave informed written consent to intervention and the study.

The diagnosis of AMI was based on chest pain persisting >30 minutes and <12 hours and ST-segment elevation >1 mm in at least 2 contiguous electrocardiographic leads or presumably new left bundle branch block. Patients received 325 mg of aspirin orally and a loading dose of 600 mg of clopidogrel (or 60 mg of prasugrel since 2010) before or immediately after the procedure. Abciximab was used routinely. Heparin was given to achieve an activated clotting time of 200 to 250 seconds. Since 2010 the use of bivalirudin was allowed. Rheolytic thrombectomy or manual aspiration thrombectomy was performed routinely if there was angiographic evidence of TIMI thrombus grade 3 to 5. IRA stenting was performed using bare-metal stents or drug-eluting stents according to the expected adherence to dual long-term antiplatelet treatment. Successful primary PCI was defined as a residual stenosis of the culprit lesion <30% and a TIMI flow grade 3. CTO was defined as a coronary obstruction with TIMI flow grade 0 and an estimated duration of >3 months. Details of the Florence CTO-PCI registry have been previously published. Briefly, the indication for the percutaneous treatment of CTO was the demonstration of viable myocardium in the territory of the occluded vessel by echographic or scintigraphic provocative tests, whereas no CTO angiographic characteristic was considered as an absolute contraindication to PCI attempt. Patients underwent PCI instead of coronary surgery because of high-surgical risk or patients’ willingness. CTO-PCI and PCI of non-IRA vessels with a stenosis >75% on visual assessment were scheduled up to 30 days after successful primary PCI. PCI was performed using standard techniques. Most CTO were attempted using the anterograde approach and dedicated coronary wires and devices. All successful recanalized CTO vessels were treated with drug-eluting stents. Procedural success was defined as a final diameter of stenosis <30% with a TIMI flow grade 3 of all CTO-treated and non–CTO-treated lesions without death, non–Q-wave or Q-wave myocardial infarction, or emergency coronary surgery. Completeness of revascularization was evaluated on post-PCI angiography and defined as a TIMI flow grade 3 with residual stenosis of <30% on visual assessment of all treated vessels. After PCI, patients were treated with aspirin (100 to 325 mg/day indefinitely) and clopidogrel (75 mg/day for 12 months) and from 2010 with prasugrel (10 or 5 mg/day for 12 months). Other drugs such as β blockers, angiotensin-converting enzyme inhibitors, and statins were used in accordance with standard and recommended practices.

All patients had scheduled clinical and electrocardiographic examinations at 6 months, 1 year, and yearly thereafter. All other possible information derived from hospital readmission or by the referring physician, relatives, or municipality live registries were entered into a prospective database. All patients were scheduled for angiographic follow-up at 6 to 9 months if not contraindicated by moderate or severe renal insufficiency (glomerular filtration rate <40 ml/min). Unscheduled angiography was allowed on the basis of clinical indication. Quantitative coronary angiography of the CTO procedure was assessed using a semiautomated edge contour detection computer analysis system (Innova 2100-IQ; General Electric Healthcare Technologies, Little Chalfont, Buckinghamshire, United Kingdom).

The primary end points of the study were 1-year and 3-year cardiac survival. All deaths were considered cardiac unless otherwise documented.

The analysis included the comparison between patients with successful CTO-PCI and patients with failed or nonattempted CTO-PCI. Discrete data are summarized as frequencies, whereas continuous data are summarized as mean ± SD or median and interquartile range, as appropriate. The chi-square or Fisher’s exact test ,when appropriate, were used for comparison of categorical variables, and the unpaired 2-tailed Student t test or Mann-Whitney rank sum test was used to test differences among continuous variables. Survival curves were generated using the Kaplan-Meier method, and the difference between groups was assessed by a log-rank test. Univariate and multivariate Cox proportional hazards models were performed to evaluate the independent contribution of clinical, angiographic, and procedural variables to long-term cardiac mortality. Variables with a p value <0.10 were entered into the multivariate model. The variables tested were age (years), male gender, diabetes mellitus, anterior AMI, previous myocardial infarction, Killip class ≥3, previous coronary surgery, ischemia time >4 hours, left anterior descending (LAD) artery CTO, 3-vessel disease, left ventricular ejection fraction (LVEF) <0.40, year of primary PCI, and successful CTO-PCI. A Cox proportional hazards model was also used to test interaction among covariates. To minimize the bias due to the nonrandomized nature of the study and the possibility of overfitting, a propensity score analysis was performed using a logistic regression model from which the probability for undergoing a CTO-PCI attempt was calculated for each patient; variables entered into propensity score model were age, male gender, diabetes mellitus, anterior AMI, Killip class ≥3, 3-vessel disease, LAD CTO, LVEF <0.40, and year of primary PCI. Model discrimination was assessed with the C-statistic and goodness-of-fit with Hosmer and Lemeshow test. Thereafter, a Cox multivariate analysis was performed to adjust successful CTO-PCI for the propensity score. All tests were 2-sided and a p value <0.05 was considered significant. Analyses were performed using the software package SPSS version 11.5 (SPSS Inc., Chicago, Illinois).

Results

From January 2003 to December 2012, 1,911 patients underwent successful primary PCI for AMI. Of these, 217 (11%) had a non-IRA CTO. Figure 1 shows the flowchart of the study. Patients with a side branch CTO (34 patients) and patients who died during the first hospitalization (14 patients) were excluded from the analysis. Of 169 patients with a non-IRA CTO of a main branch, a staged CTO-PCI attempt was performed in 74 patients (44%) and was successful in 58 of them (success rate 78%). Patients did not undergo PCI attempt because of low likelihood of PCI success, renal insufficiency, or patient’s refusal. In patients with 3-vessel disease, a strategy of routine PCI of the third non-CTO vessel was adopted. Patients were divided in 2 groups based on successful revascularization of the CTO (58 patients) or failed or nonattempted CTO-PCI (111 patients).

Patient flow diagram.

Baseline characteristics of the 2 groups are summarized in Table 1 . Patients with successful CTO-PCI were younger than those with failed or nonattempted CTO-PCI, and anterior AMI, moderate or severe left ventricular dysfunction on admission (LVEF <0.40), and LAD CTO were more frequent in the successful CTO-PCI group. Thus, in the successful CTO-PCI group, the involvement of LAD, either as IRA or as chronically occluded vessel, was significantly more frequent than the failed or nonattempted CTO-PCI group (81% vs 50%, p <0.001). Significant left main disease (>50% stenosis on visual assessment) was present in 19% of the successful CTO-PCI group and in 9% of the failed or nonattempted CTO-PCI group (p = 0.085). Table 2 depicts the procedural characteristics of the primary PCI, CTO-PCI, and other vessel PCI. Most patients with 3-vessel disease underwent PCI of the non-IRA non-CTO vessel (79% in the successful CTO-PCI group and 85% in the failed or nonattempted CTO-PCI). No major complications occurred in patients who underwent non-IRA PCI (death, Q-wave myocardial infarction, cardiac tamponade, or emergency cardiac surgery). All patients with successful CTO-PCI received drug-eluting stents in CTO lesions. In the successful CTO-PCI group, a complete coronary revascularization was achieved in 88% of the patients.

Table 3 depicts clinical and angiographic outcomes. The median length of the follow-up was 3.9 years [interquartile range 2.4 to 6.5]. Overall, at 1 year (clinical follow-up rate 100%), there were 5 noncardiac deaths and 14 cardiac deaths (8.3%). Ten patients died of refractory congestive heart failure, whereas the other 4 cardiac deaths were because of probable or possible stent thrombosis according to the Academic Research Consortium definition. One-year cardiac mortality was higher in patients with failed or nonattempted CTO-PCI compared with the successful CTO-PCI group (12% vs 1.7%, p = 0.025). The 3-year cardiac survival rate was significantly higher in patients of the successful CTO-PCI group as compared with those with a persistently occluded vessel (96 ± 3% vs 85 ± 3%, p = 0.030; Figure 2 ). In the persistently occluded vessel group, there was no difference between failed and nonattempted CTO-PCI patients in the long-term survival ( Figure 2 ). Table 4 summarizes univariate and multivariate adjusted analyses. By multivariate analysis, successful CTO-PCI was inversely associated with 3-year cardiac mortality (hazard ratio 0.20, 95% confidence interval 0.05 to 0.92, p = 0.038). Successful CTO-PCI remained a strong predictor inversely related to long-term cardiac mortality (hazard ratio 0.19, 95% confidence interval 0.04 to 0.88, p = 0.034) even after adjusting for the propensity score for CTO-PCI attempt (C-statistic of the regression model was 0.75 and the Hosmer-Lemeshow goodness-of-fit test was p = 0.940).

Table 3

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