Advantages and disadvantages of biodegradable platforms in drug eluting stents

Table 1 Comparison between published trials of biodegradable eluting stents

Name	Polymer	Stent design	Drug	Drug per stent length (μg/mm2)	Polymer degradation	Drug release
ISAR-TEST-3[35]	PLA	316L stainless steel microporus stent	Sirolimus	4.8	6-9 wk	28 d (95%)
ISAR TEST-4[36]	PLA	316L stainless-steel microporus stent	Sirolimus	4.8	6-9 wk	28 d (95%)
NOBORI 1[34]	PLA	Stainless-steel S-stent	Biolimus	15.6	9-12 mo	Two phases: immediately after stent implantation; sustained drug release over 9-12 mo
NOBORI CORE[33]	PLA	Stainless-steel S-stent	Biolimus	15.6	9-12 mo	Two phases: immediately after stent implantation; sustained drug release over 9-12 mo
LEADERS[28]	PLA	Flexible stainless- steel stent	Biolimus	15.6	6-9 mo	6-9 mo
PAINT[38]	PLA+	316L stainless metallic platform	Paclitaxel and Sirolimus	6.4 (PES)	7 mo	9-11 d (50%)
	PLGA			6.6 (SES)		38 d (90%)
						48 d (100%)
EUCATAX[39]	PLGA	Stainless steel open cell with glycocalix layer	Paclitaxel	11 to 43	6-8 wk	6-8 wk

PLA: Polylactic acid; PLGA: Polylactic-co-glycolic acid; PES: Paclitaxel-eluting stent; SES: Sirolimus-eluting stent; ISAR: Individualized Drug Eluting Stent System to Abrogate Restenosis; LEADERS: Limus Eluted from a Durable vs Erodable Stent Coating.

Table 2 Quantitative coronary analysis for both groups in the EUCATAX trial n (%)

	PES	BMS	P value
Baseline QCA analysis	n = 169	n = 153
Reference diameter (mm)	2.75 ± 0.5	2.85 ± 0.5	0.086
Minimal luminal diameter (mm)	0.86 ± 0.4	0.85 ± 0.5	0.780
Lesion length (mm)	16.2 ± 6.1	15.6 ± 6.3	0.410
Stent diameter (mm)	21.7 ± 5.6	20.0 ± 4.8	0.160
Stent size (mm)	2.96 ± 0.4	2.93 ± 0.5	0.780
Immediately Post PCI QCA analysis
Reference diameter (mm)	2.91 ± 0.44	2.96 ± 0.43	0.340
Minimal luminal diameter (mm)	2.68 ± 0.42	2.72 ± 0.43	0.400
Follow up QCA analysis	n = 98	n = 88
Reference diameter (mm)	2.75 ± 0.48	2.75 ± 0.36	0.990
Minimal luminal diameter (mm)	2.16 ± 0.51	1.81 ± 0.75	0.007
Stenosis diameter (%)	27.4 ± 29.8	39.6 ± 23.9	0.005
Acute gain	1.82 ± 0.47	1.87 ± 0.62	0.450
Net gain	1.30 ± 0.49	0.93 ± 0.63	0.002
Late loss (in-stent)	0.52 ± 0.59	0.94 ± 0.70	0.002
Late loss (in-segment)	0.50 ± 0.56	0.91 ± 0.069	0.001
Angiographic restenosis	13 (13.2)	31 (35.2)	0.001
Follow up intravascular ultrasound analysis	n = 45	n = 37
Stent length (mm)	21.7 ± 5.6	20.0 ± 4.8	0.160
Stent size (mm)	2.96 ± 0.4	2.93 ± 0.5	0.780
Incomplete stent apposition	5 (11.1)	9 (24.3)	0.150
Proximal segment	1 (2.2)	8 (21.6)	0.015
Body segment	2 (4.4)	1 (2.7)	1.000
Distal segment	2 (4.4)	0 (0.0)	0.500

QCA: Quantitative coronary analysis; PCI: Percutaneous coronary intervention; BMS: Bare-metal stent.

Table 3 Comparison between published trials of biodegradable eluting stents

Name	Stent design	Cardiac death	Cardiac death or MI	MI	TVR	TLR
LEADERS[28]	Biomatrix	2.1	6.7	5.8	7.8	6.5
	Cypher	2.7	6.6	4.6	9.9	7.4
	Nobori	0.0	-	4.7	7.1	0.0
NOBORI[34]	Taxus	0.0	-	8.6	14.3	2.9
ISAR-TEST-3[35]	Biodegradable polymer stent	2.0	2.5	1.5	-	5.9
	Permanent polymer sirolimus	2.0	3.5	2.0	-	7.9
	Polymer free sirolimus	2.0	4.0	2.5	-	12.9
ISAR-TEST-4[36]	Biodegradable polymer	2.8	6.3	4.3	13.7	8.8
	Control1	3.2	6.2	4.1	13.9	9.4
EUCATAX[39]	PES	1.9	4.7	2.8	8.2	6.1
	BMS	1.9	4.3	2.4	15.0	12.6

¹Control reflects results of Cypher (Cordis, Florida, USA) or Xience (Abbott Vascular, Abbott Park, IL, USA). MI: Myocardial infarction; TVR: Target vessel revascularization; TLR: Target lesion revascularization; ISAR: Individualized Drug Eluting Stent System to Abrogate Restenosis.

Table 4 Comparison of baseline characteristics and follow up angiographic and clinical results from the randomized LEADERS[28] and EUCATAX[39] trials

Patients characteristics	BioMatrix	Cypher	EucaTax	P values
No. of patients	857	850	211
Age (yr)	65 ± 11	65 ± 11	63.8 ± 10.2	0.32
Male gender	75.0	75.0	83.4	0.62
Hypertension	74.0	73.0	64.0	0.46
Diabetes mellitus	26.0	23.0	23.2	0.49
Hypercholesterolemia	65.0	68.0	56.9	0.36
Smoking	24.0	25.0	21.3	0.68
Previous MI	32.0	33.0	20.4	0.02
Previous PCI	36.0	37.0	35.5	0.93
Multi vessel disease	37.0	32.0	55.0	< 0.001
Clinical presentation
Acute coronary syndrome	55.0	56.0	59.7	0.80
Lesions per patient
> 1 lesion	29.0	22.0	26.1	0.09
Small vessels1	68.0	69.0	60.3	0.45
Procedural characteristics
Stents per lesion	1.3 ± 0.7	1.3 ± 0.7	1.36 ± 0.5	0.38
Stent length per lesion (mm)	24.7 ± 15.5	24.6 ± 14.8	21.7 ± 5.6	0.006
Angiographic follow-up
In-stent late loss	0.08 ± 0.4	0.15 ± 0.4	0.52 ± 0.6	< 0.001
Stent thrombosis2
Overall stent thrombosis	3.6	3.3	1.4	0.28
Definite ST
0-30 d	1.6	1.6	0.5	0.43
> 30 d-12 mo	0.4	0.5	0.9	0.52
0 d-12 mo	2.0	2.0	1.4	0.82
Efficacy endpoints at 12 mo
Any TLR	6.5	7.4	6.1	0.63
Any TVR	7.8	9.9	8.2	0.23
Safety endpoints at 12 mo
All causes of death	3.2	3.3	2.4	0.80
Cardiac death	2.1	2.7	1.9	0.66
Myocardial infarction	5.8	4.6	2.8	0.11
Cardiac death or MI	6.7	6.6	4.7	0.46

¹Small vessel was defined as any vessel diameter with less than 2.75 mm;

²Stent thrombosis definition by the Academic Research Consortium. MI: Myocardial infarction; PCI: Percutaneous coronary intervention; RVD: Reference vessel diameter; QCA: Quantitative coronary angiography; MLD: Minimal luminal diameter; DS: Diameter stenosis; TLR: Target lesion revascularization; TVR: Target vessel revascularization.