Clinical outcome after PCI for chronic total occlusions

Cardiology Review® Online, August 2004, Volume 21, Issue 8

From the Division of Cardiology, Ospedale Cà Foncello, Treviso; Division of Cardiology, Ospedale San Martino, Genoa; and Institute of Cardiology, Federico II University, Naples, Italy

Recanalization of chronic total occlusions has a lower immediate success rate and a higher restenosis rate compared with subtotal stenoses and is therefore a major problem confronting interventionists. In recent years, because of the use of improved guidewires and greater experience on the part of operators, the success rate for the procedure has improved; restenosis and reocclusion rates have also improved as a result of stent implantation.

Several studies have indicated that successful percutaneous coronary intervention (PCI) for a chronic total occlusion may have a positive effect on long-term survival.1-4 To assess the success rate, the current in-hospital and 12-month clinical outcome, and their association with predefined clinical and angiographic variables, we performed a prospective, multicenter, observational study on consecutive patients treated with PCI for a chronic total occlusion.

Patients and methods

During a 6-month period in late 1999, recanalization of 390 chronic total occlusions was attempted in 376 consecutive patients treated in 29 Italian centers. Chronic total occlusion prevalence among the population of patients receiving PCI was 7.1% ± 2.9%. Patients were considered to have a chronic total occlusion if they had an obstruction of a native coronary artery with a Thrombolysis in Myocardial Infarction (TIMI) grade 0 or 15 for a duration of more than 30 days. All technical and procedural details were left to the operator’s judgment. All patients received aspirin indefinitely and, in case of stent implantation, ticlopidine or clopidogrel for 4 weeks.

An independent core laboratory assessed all quantitative and qualitative angiographic variables. An improvement in TIMI flow to grade 2 or 3, with a residual stenosis of less than 50%, was considered to be a successful procedure. In-hospital death, Q-wave and non—Q-wave myocardial infarction (MI), urgent coronary artery bypass graft (CABG) surgery, or urgent repeated PCI were considered major adverse cardiac events. Procedural success was defined as technical success without in-hospital major adverse cardiac events. At the 12-month clinical follow-up, freedom from major adverse cardiac events was defined as freedom from cardiac death, Q-wave and non–Q-wave MI, or target lesion revascularization.

Results

In-hospital results. Most patients (69%) had a history of MI, usually in the area of the myocardium supplied by the target vessel (62%). The patients frequently had stable or unstable angina (88%). Eighteen percent of patients had diabetes, and about 50% had multivessel disease. In 70% of patients, wall motion in the area supplied by the target vessel was normal or only reduced, indicating viability of the myocardium. The left ventricular ejection fraction was 55.9% ± 9.7%. Most patients (82.5%) with chronic total occlusions had TIMI grade 0; 40% of the chronic total occlusions were located on the left anterior descending artery, 38% were on the right coronary artery, and 22% were on the left circumflex artery. The duration of the chronic total occlusions could not be estimated in 30% of patients. The estimated duration was 176 ± 439 days for the rest of the occlusions. The mean length of the chronic total occlusions was 13.4 ± 9.13 mm; the length could not be determined for 50% of patients, however. In 89.7% of chronic total occlusions that were successfully recanalized, at least one stent was implanted. Thirty-nine patients (10.4%) received glycoprotein IIb/IIIa antagonists.

One patient had a massive pulmonary embolism 48 hours after successful PCI and died. Emergency CABG surgery was performed on two patients. In addition, 16 patients (4.3%) experienced a non—Q-wave MI. Overall, 19 patients (5.1%) experienced in-hospital major adverse cardiac events. Technical success was achieved in 77.2% of cases; procedural success was achieved in 73.3% of cases. Technical failure most often occurred because the lesion could not be crossed with a guidewire (81% of patients) and, less frequently, the lesion was not able to be crossed or to be dilated with a balloon (19% of patients). The presence of multivessel disease was significantly more frequent in patients with failed PCI (59.8% versus 44.6%; P = .013), whereas the other baseline clinical characteristics were similar for patients with successful and failed PCI.

Determinants of procedural outcome. At multivariate analysis, the following characteristics were significantly correlated with technical failure of the PCI: a length of the chronic total occlusion of 15 mm or longer (hazard ratio [HR], 3.9; 95% confidence interval [CI], 1.1—13.5) or one that was not measurable (HR, 3.8; 95% CI, 1.2–11.8); chronic total occlusion of 180 days’ duration or longer (HR, 3.1; 95% CI, 1.3–7.4); the presence of moderate to severe calcifications (HR, 3.5; 95% CI, 1.1–10.1); the presence of multivessel disease (HR, 2.3; 95% CI, 1.2–4.3); indeterminable stump morphology (HR, 2.2; 95% CI, 1.0–4.8).

One-year follow-up. In 98% of cases discharged without having had CABG surgery, the clinical follow-up was completed. During the follow-up period, six patients died. One patient died of esophageal cancer, and one died from stroke. The other four patients died of cardiac causes. Only one Q-wave MI occurred. There was a markedly lower incidence of overall major adverse cardiac events, cardiac deaths, and the composite end point of cardiac death or MI, as well as a reduced need for CABG surgery, in patients who had undergone a successful PCI, compared with patients who underwent a failed procedure (figure 1). However, the higher incidence of cardiac death or MI after failed procedures was evident only in patients with multivessel disease (figure 2).

A multivariate analysis of baseline clinical, angiographic, and procedural characteristics showed that the initially successful PCI was the only variable that markedly correlated with survival free of a major adverse cardiac event (odds ratio, 0.24; 95% CI, 0.07—0.8).

Figure 3 shows the clinical status of the PCI after 1 year for 308 patients free of a major cardiac event. Patients who had a successful procedure had fewer symptoms of angina and better exercise tolerance.

Discussion

Most of the literature regarding PCI of chronic total occlusions is based on studies that reported early results from one center, which is usually experienced in treating occluded coronary arteries. New guidewires and other devices designed to treat chronic total occlusions have become available in the past few years. There are no data, however, regarding their effect on outcomes in unselected patients. In addition, it is not known whether the clinical and angiographic predictors of procedural outcome identified in early studies are still relevant today. Our study was designed to investigate the “state-of-the-art” results of PCI for chronic total occlusions in current interventional practice.

In our study, the technical success rate (77%) and the procedural success rate (73%) are comparable with earlier studies conducted at a single center.1-4,6-13 In previous studies, the technical and procedural success rates varied between 51% and 73%, respectively. The rate of in-hospital major adverse cardiac events in our study was 5.1% (mostly due to non-Q-wave MI), which was similar to that reported in other studies.3,4,6,8-11 Angiographic variables that were shown to be predictive of a failed procedure in previous studies, such as the presence of a side branch at the chronic total occlusion stump,11,12 bridging collaterals,8,11 abrupt stump morphology,1-4,8 and TIMI grade 0,1,6 were not predictive in our study.

Procedural failures only correlated with a chronic total occlusion length of 15 mm or longer, or one that was not measurable; presence of multivessel disease; chronic total occlusion duration of 180 days or longer; presence of moderate to severe calcifications of chronic total occlusions; and stump morphology that was not identifiable.

Compared with those patients who had a successful procedure, our study showed a greater incidence of cardiac death, combined rate of cardiac death and MI, and CABG surgery in patients with a failed procedure at the 1-year follow-up (figure 1). In addition, patients with multivessel disease had a higher rate of combined cardiac death and MI compared with those with single-vessel disease (figure 2). Other researchers have reported a higher incidence of cardiac death and MI in patients after failed procedures, but not as early as at the

1-year follow-up.1-4 Future studies with a longer follow-up period are needed to confirm this finding because it is based on the occurrence

of only a few events, although it

was statistically significant. All the available data on the prognostic advantages of PCI on chronic total occlusions are based on the comparison between patients with suc-

cessful and unsuccessful procedures. Whether, and in which patients, recanalization of a chronic total occlusion can improve the clinical outcome requires further examination.

The results of our study are similar to other studies that have shown a higher rate of CABG surgery for patients with failed procedures.1-3,9 After a successful procedure, the revascularization rate for the target lesion was extremely low (11.5%), which was most likely a result of the extensive use of stents and the fact that no routine angiographic control was scheduled.

The favorable functional outcome of the procedure was borne out by the fact that 89% of patients with no major adverse cardiac events did not have symptoms of angina after a successful PCI, and 63% of those performing an exercise test were able to reach the maximum heart rate for their age (figure 3). Other studies have shown similar results.14

Conclusions

In the current study, the procedural and technical success rates for PCI of chronic total coronary occlusions were high, with few complications. Patients who underwent a successful PCI had a more favorable clinical outcome after 12 months,a lower incidence of cardiac death and MI, better clinical status with less angina, a lower incidence of CABG surgery, and better results on exercise testing. Characteristics that predicted technical failure included length of occlusion, duration of occlusion, presence of multivessel disease, and presence of moderate to severe calcifications. This was the largest reported multicenter study of consecutive patients treated with PCI for chronic total occlusions with independent core laboratory evaluation of all angiographic variables.