TAXUS VI: A Randomized Trial of Moderate-Rate-Release, Polymer-Based, Paclitaxel-Eluting Stent for the Treatment of Longer Lesions – 9-Month Clinical Results

Luis Gruberg, MD, FACC

Disclosures

July 12, 2004

Editorial Collaboration

Medscape &

Presenter: Eberhard Grube, MD, Heart Center (Siegburg, Germany)

The series of TAXUS studies demonstrated the safety and efficacy of both slow- and moderate-release formulations of the paclitaxel-eluting TAXUS stent (Boston Scientific; Natick, Massachusetts) in patients with short lesions.

As we know, both the slow-release (SR), as well as the moderate-release (MR) formulation carry the same amount of drug (1 μg/mm2) and have similar release kinetics (biphasic). However, they differ with respect to the drug that is released in vivo; the TAXUS MR stent provides almost 3 times more local drug release compared with the TAXUS SR stent (12 mcg vs 33 mcg, respectively). The former has been approved for commercial use in the United States and Europe, while the latter is still considered investigational. The effect of the MR stent in longer and more complex lesions is unknown.

Study Design and Results

TAXUS VI is the first randomized, controlled trial to evaluate the outcomes of the paclitaxel-eluting TAXUS MR stent compared with control in patients with long and complex lesions.

A total of 446 patients were randomized to either control (n = 227) or to receive the TAXUS MR stent (n = 219). Clinical follow-up was performed at 9 months, and follow-up data are available for 437 patients (98%). The study's primary endpoint was target vessel revascularization (TVR).

The overall patient cohort enrolled in TAXUS VI represented a high-risk population, characterized by long lesions, small vessels, and a high incidence of diabetes (Table 1). Baseline lesion and procedural characteristics were well balanced between the 2 groups (Table 2).

Table 1. TAXUS VI: High-risk Characteristics of Overall Patient Cohort
Characteristic Patients (N = 446)
Lesion length (mm) 20.6
Total stent length (mm) 33.4
AHA/ACC type C lesions (%) 55.6
Small vessels (< 2.5 mm) (%) 27.8
Overlapping stents (%) 27.8
PCI in an additional nontarget vessel (%) 23.5
Diabetes (%) 20.0
Insulin-dependent (%) 39.3
AHA/ACC = American Heart Association/American College of Cardiology; PCI = percutaneous coronary intervention
Table 2. TAXUS VI: Lesion and Procedural Characteristics
Control (n = 227) TAXUS MR (n = 219)
Lesion Characteristics
Reference vessel diameter (mm) 2.77 ± .046 2.81 ± 0.49
Percent diameter stenosis 68.6 ± 10.65 70.2 ± 10.67
Lesion length (mm) 20.32 ± 7.88 20.94 ± 7.21
AHA/ACC type C lesions (%) 53.7 57.5
Procedural Characteristics
Number of stents per patient 1.5 1.5
Total stent length (mm) 33.2 ± 10 33.7 ± 11
Stent/lesion length ratio 1.8 ± .07 1.7 ± .06
GP IIb/IIIa inhibitors (%) 19 21
AHA/ACC = American Heart Association/American College of Cardiology; GP = glycoprotein

At 9-month follow-up, TVR rates were significantly lower in the TAXUS MR arm compared with control (9.1% vs 19.4%, respectively; P = .0027), accounting for a 53% reduction in the relative risk for TVR (Figure 1). Target lesion revascularization (TLR) rates were also significantly lower in the TAXUS arm (Figure 1); use of the TAXUS MR stent was associated with a 64% reduction in the relative risk for TLR.

Figure 1. TAXUS VI: TVR and TLR at 9-month follow-up.

As expected, there was a low incidence of major adverse cardiac events (death, Q-wave myocardial infarction [MI], and non-Q-wave MI), with no significant differences between the 2 groups (Figure 2). There was only 1 case of stent thrombosis reported throughout the course of the study (reported at 30-day follow-up) in the TAXUS MR arm.

Figure 2. TAXUS VI: major adverse cardiac events (death, myocardial infarction, TVR) at 9-month follow-up.

Analysis by classic risk factors for restenosis (small vessel, long lesions, diabetes, and overlapping stents) demonstrated that the TAXUS MR stent was associated with a universal benefit that was independent of risk factors for restenosis (Figure 3).

Figure 3. TAXUS VI: independent risk factors for TLR at 9-month follow-up.
Conclusions

On the basis of the TAXUS VI results, investigators concluded:

  1. The TAXUS MR stent had excellent safety characteristics in patients with long lesions requiring complex interventional procedures compared with the control arm.

  2. The primary endpoint of TVR was met at 9-month follow-up.

  3. There was a 64% reduction in the relative risk for TLR.

  4. The benefit was independent of classic risk factors, such as small vessels, long lesions, presence of diabetes, or overlapping stents.

Comments

These results provide further evidence documenting the safety and efficacy of the TAXUS MR stent in a very complex population -- one that most likely reflects the types of cases observed in daily practice.

These results provide ample support for the use of drug-eluting stents in complex cases -- something the interventional community is already aware of and is likely already practicing.

Comments

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