INTRODUCTION
Since percutaneous transluminal coronary angioplasty (PTCA) was first introduced in 1977 by Gruentzig as a treatment for proximal short-segmental, non-calcified, concentric isolated coronary stenosis1), it has been used with increasing frequency in patients of symptomatic coronary artery disease with broader indications, including multi-vessel disease, unstable angina, acute myocardial infarction and totally occluded coronary arteries. Among these, total coronary occlusion constitutes a subdivision with specific features that require separate evaluation. The purpose of this study was to determine the initial results of PTCA for total coronary occlusion.
MATERIALS AND METHODS
1. Patients
Thirty-five patients with manifested ischemic heart disease with totally occluded coronary arteries, documented by coronary angiography, underwent recanalization procedures by PTCA between Jan. 1990 and Oct. 1991. Total occlusion was defined as complete absence of forward flow (TIMI flow 0). But functional total occlusion, defined as trivial antegrade flow with major filling of the distal vessel predominantly by collaterals (TIMI flow 1), was excluded. Duration of occlusion was estimated from clinical data (time of infarction or sudden increase in anginal symptoms) or from the date of previous angiogram that did not show occlusion. Success was defined as an improvement in the stenosis by 50% or more of the luminal diameter without major complication.
2. Methods
PTCA was performed from femoral artery approach in each case, using an over-the guide-wire system. If attempts to cross the site of occlusion with a flexible guide wire were unsuccessful, a less flexible, steerable guide wire or magnum wire was used. Coronary angiograms obtained after successful angioplasty were evaluated closely for evidence of distal small vessel cut-off or pruning. Electrocardiogram and cardiac enzyme levels were evaluated for all patients before angioplasty and after procedure. After successful angioplasty, patients were maintained on intravenous heparin infusion for 24 hours. All patients received oral aspirin three days before and indefinitely after PTCA.
The differences in outcome of dilatation were tested by means of chi-square analysis. A p value<0.05 was considered significant.
RESULTS
Table 1 summarizes the patient characteristics. They were 28 men and 7 women with a mean age of 55±10 years. Twenty patients (57.1%) were acute myocardial infarction, 7 old myocardial infraction (20%) and 8 unstable angina.
Twenty-eight patients had one or more major atherosclerosis risk factors and 10 patients had two or more major atherosclerosis risk factors (Table 2).
Attempted lesions were the left anterior descending artery in 19 (51.4%), the right coronary artery 14 (40%), left circumflex artery 2 (5.7%), and protected left main one. Twenty two patients (63%) had single-vessel disease and 12 patients had multi-vessel disease and one had left main disease (Table 3).
In 21 patients with a duration of occlusion less than 2 weeks, the success rate was 71% (15 of 21), while in patients with duration of occlusion from 2 to 12 weeks, the success rate was 63% (5 of 8) and the success rate was 50% in 6 patients with duration of occlusion longer than 12 weeks (3 of 6) (Table 4).
The outcome of coronary angioplasty was not significantly influenced by the age and sex of the patients, associated risk factors and the number of involved vessels, but the procedural success rate was higher on the RCA than on the LAD (p<0.05) (Table 5).
The mean percentage of stenosis decreased from 100% to 20.5% in left anterior descending artery, 19.1% in right coronary artery and 17.0% in left circumflex artery (Table 6).
The most common reason of the procedural failure was inability to cross the lesion with the wire in 9 patients and inability to follow the wire across the lesion with balloon catheter in 3 (Table 7).
Distal embolization was observed in 2 patients with successful PTCA. Other complication included spiral intimal dissection in one, acute reocclusion in one and prolonged chest pain in one (Table 8).
DISCUSSION
Since PTCA of total coronary occlusion was first reported by Savage et al2), many study groups have reported the initial and late results of PTCA of this disease. The reported overall initial success rate ranged from 63% to 72%3–10). Our primary success rate without significant residual stenosis was 66%. This result is similar to initial success rates previously reported. Many study groups have reported that the main factor that determines the outcome of PTCA for occlusion is duration of occlusion5,7,9) i. e the age of the lesion. Thus, older lesions are less likely to be crossed with the guidewire. In the present study, the success rate was 71% in patients with a duration of occlusion less than 2 weeks, but it was 50% in patients with duration of occlusion longer than 12 weeks. The reports from Stone et al3) identified the bridging collateral vessels and the tapered occlusion morphology as independent factors of procedural outcome. Other variables, including the estimated duration of occlusion, lesion length and location and extent of disease, were unrelated to success.
With present technique and sufficient operator experience, 70% to 80% of total occlusion could be successfully recanalized by coronary angioplasty with a lower complication rate3).
Careful case selection, with attention to angiographic variables related to procedural success, may be expected to improve procedural outcome. Holmes et al4) suggested that certain precautions should be taken with dilatation of completely occluded arteries. First, perfusion of the myocardium in the distribution of the occluded vessel relies on the remaining coronary vessels. Care must be taken to avoid trauma to the nondilating segments that supply these vessels. Second, it is important to visualize the course of the distal vessel and thus determine the proper route for the dilating catheter. This may be possible by reviewing films before the time of complete occlusion or by visualizing the distal vessel by way of collateral channels.
This study suggested that PTCA of total coronary artery occlusion can be performed safely and effectively in selected cases and might be more successful in the lesion with shorter duration of occlusion. But total coronary occlusion is the main limiting factor of PTCA with guide wire technique. New technique has been developed to achieve the higher success rate for the recanalization of chronically occluded coronary arteries, such as low-speed rotational angioplasty or laser angioplasty11–12). And the long-term clinical and angiographic follow-up in patients having successful recanalization of an occluded coronary vessel should be done to determine the long-term benefit of the procedure.
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