Impact of Chocolate percutaneous transluminal angioplasty balloon on vessel preparation in drug-coated balloon angioplasty for femoropopliteal lesion

doi:10.21203/rs.3.rs-1631877/v1

Purpose: Compare the impact of Chocolate and conventional balloons on vessel preparation in percutaneous transluminal angioplasty.

Materials and Methods:

Study included 111 endovascular therapy consecutive cases of femoropopliteal lesions using drug-coated balloon strategy with a 1:1 pre-dilation balloon diameter between February 2020 and August 2021, divided into the Chocolate percutaneous transluminal angioplasty (n=48) and conventional (n=63) groups. Before the availability of Chocolate balloons in Japan (December 2020), a standard semi-compliant or non-compliant balloon was used for vessel preparation. Since its availability, Chocolate percutaneous transluminal angioplasty balloons are used. Primary endpoint was rate of severe dissection after pre-dilatation. Secondary endpoints were angiographic percent diameter stenosis, bailout stent rate, primary patency rate, and freedom from target-lesion-revascularization rate at six months.

Results:

There was no significant difference in patient and lesion characteristics. Procedural characteristics comprised balloon length 90±37 mm and 149±95 mm (P=0.004) and inflation pressure 11±3 atm and 16±7 atm (P<0.001) in the Chocolate and conventional groups, respectively. Regarding primary endpoint, rates of severe dissection were 4.2% and 25% (P=0.003); regarding secondary endpoints, percent diameter stenosis was 18±15% and 20±17% (P=0.409), and the rate of bailout stenting was 2.1% and 15.9% (P=0.016) in the Chocolate and conventional groups, respectively. Primary patency rates at six months were 89.1% and 85.2% (P=0.670), and freedom from target-lesion-revascularization rate at six months was 100% and 92.8% (P=0.691) in the Chocolate and conventional groups, respectively.

Conclusion:

Chocolate percutaneous transluminal angioplasty balloons reduce the rate of severe dissection while maintaining sufficient dilatation effect in drug-coated balloon vessel preparation.

Peripheral artery disease

Endovascular procedures

femoral artery

Popliteal artery

Drug-coated balloon

Recent advances in endovascular treatment (EVT) technology and related devices have made EVT the first-line treatment for peripheral arterial disease with femoropopliteal (FP) lesions.[1] Use of nitinol stents has led to excellent acute lumen gains in the past two decades; however, primary patency remains unsatisfactory.[2,3] To extend procedure durability in FP lesions, paclitaxel-eluting stents were developed to preclude neointimal proliferation in FP lesions by enabling sustained and controlled release of paclitaxel over the first 12 months after stent implantation.[4] Contrastingly, the use of a drug-coated balloon (DCB) has been suggested as a feasible alternative, especially in popliteal lesions, small vessel diseases, and young claudicants, to overcome the shortcomings of metallic stents (such as in-stent restenosis and fractures).[5,6] The Society for Cardiovascular Angiography & Interventions Consensus Guidelines[7] recommend DCB as the final device for FP lesions. Although current investigations prove the efficacy of DCB in long FP lesions as a newly established treatment,[8,9] rate of bailout stenting is not low because of flow-limiting dissection after angioplasty. Fujihara et al.[10] reported a dissection rate of 42% in severe, flow-limiting dissections (types C–F) post-balloon angioplasty of superficial femoral artery (SFA); majority of which required subsequent intervention and bailout stenting. To address high prevalence of dissections and to ensure metal-free interventions in future, new angioplasty balloon technologies are required.

Chocolate percutaneous transluminal angioplasty (PTA) balloon catheter is a balloon developed to minimize overall vessel trauma. This balloon is constrained by a nitinol scaffold that subsegments the balloon when inflated, creating valleys and grooves on the balloon surface that increase its contact surface area. This balloon design intends is to disperse the force associated with angioplasty along this increased contact surface area, resulting in a controlled and differential dilatation approach to minimize overall vessel trauma.[11] A prior study showed short-term procedural results without flow-limiting dissections. This strategy minimizes bailout stent use and provides an alternative to primary stenting with excellent 12-month primary patency rates and low rates of target lesion revascularization (TLR).[11] However, there have been no studies comparing them with conventional balloons. Therefore, this study investigated the impact of a chocolate PTA balloon on vessel preparation for angioplasty and compared it with that of a conventional balloon.

Patients

This single-center, retrospective, nonrandomized observational study was conducted between April 2020 and August 2021. Chocolate PTA balloon has been available in Japan since December 2020. The main strategy for FP lesions in this study was DCB angioplasty, except in cases of severely calcified lesions, thrombotic lesions, and chronic limb-threatening ischemia (CLTI) with a large wound.

During the study period, EVT was performed in 242 consecutive cases of FP lesions. Exclusions comprised: in-stent restenosis lesions (n=43), clinical trial cases (n=3), thrombotic lesions (n=25), cases with primary stent strategy because of calcified lesions (n=23), and CLTI with large wounds (n=25). To match the diameter of the pre-balloon with the reference vessel size of 1:1, cases (n=12) in which pre-dilatation balloons were selected with a diameter of 1 size down were excluded. According to the type of pre-dilated balloon, 111 patients (111 lesions) were divided into the chocolate PTA (n=48) and conventional (n=63) groups (Fig. 1).

All patients had symptoms corresponding to categories 2–6 of Rutherford classification[3]after exercise and drug therapy. When an occlusive lesion was found in the FP vessels on angiography, vascular surgeons and interventional cardiologists discussed whether EVT was indicated.

This study protocol was developed in accordance with the Declaration of Helsinki

and approved by the ethics committee.

Interventions

Ipsilateral or crossover approach was used for EVT. In this approach, 6-French (Fr) or 7-Fr sheaths were inserted, and unfractionated heparin (5000 U) was injected intraarterially. After a 0.014-inch guidewire was passed through the target lesion, intravascular ultrasound (IVUS) images were recorded by a manual pullback. Pre-dilatation was sized at 1:1 with the target vessel diameter.

The method of expanding a chocolate PTA balloon is described in a previous study,[11] which comprises inflating a chocolate PTA balloon to half nominal for 30 s, followed by slow inflation to nominal for an additional 90 s. Conventional balloons slowly expand to the target pressure for approximately 2 minutes. Conventional balloons were used till December 2020, after which chocolate PTA balloons became available and were used instead for pre-expansion. Conventional balloons include non-compliant and semi-compliant balloons.

After pre-expansion, if the residual stenosis was less than 50% or type C or less dissection, DCB was selected as the final device. If there was significant dissection or insufficient expansion, bailout stent placement was performed.

Medical therapy

Dual antiplatelet therapy with aspirin (100 mg/day) plus ticlopidine (200 mg/day), clopidogrel (75 mg/day), or cilostazol (200 mg/day) was prescribed for at least three days before EVT. It was continued for at least one month after that.

Study definitions and clinical follow-up

Rate of severe dissections was the primary endpoint. Secondary endpoints included percent diameter stenosis (%DS) after pre-dilatation, rate of bailout stenting, primary patency at six months, and freedom from TLR at six months. Clinical evaluation was performed at one, three, and six months. Duplex ultrasound assessment was performed routinely at one, three, and six months after EVT to evaluate vessel patency.

When duplex ultrasonography suggested stenosis or occlusion, angiography was performed for confirmation. Restenosis was defined as a peak systolic velocity ratio of >2.4 on a duplex ultrasound image, which indicated >50% narrowing, or >50% diameter stenosis or occlusion on angiography.[12] CLTI was defined as described previously.[13] All lesions within the FP segment were characterized according to the Trans-Atlantic Inter-Society Consensus-II (TASC-Ⅱ) classification.[14] The proposed Peripheral Arterial Calcium Scoring System (PACSS) was used to categorize the degree of lesion calcification.[15] Below-the-knee (BTK) runoff was assessed using pre-angiography. Poor tibial vessel runoff was defined as runoff in one or no BTK vessel.[16] All angiograms were independently evaluated by two experienced operators. Angiographic dissection was classified according to the National Heart, Lung and Blood Institute (NHLBI) dissection classification system,[17] which defines flow-limiting dissection as types E and F. Severe dissection was defined as type C or higher in the NHLBI classification.[10] TLR was defined as a repeated endovascular or surgical procedure for the treated lesion.

Statistical analysis

Statistical analyses were performed using JMP software version 13.0.0 (SAS Institute, Cary, NC, USA). Continuous variables are reported as mean±standard deviation and were compared using t-test. Categorical variables were reported as count (percentage) and were compared using chi-squared test or Fisher’s exact test. All baseline values and procedure characteristics were assessed using univariate logistic regression analysis to identify independent predictors of the bailout stent. Estimates of primary patency and TLR rates were calculated using Kaplan–Meier method, and intergroup differences were assessed using log-rank test. In all analyses, statistical significance was set at p<0.05.

Patients and procedural characteristics

Baseline characteristics are shown in Table 1. There were no significant differences in patient and lesion characteristics. Procedural characteristics are shown in Table 2. In the pre-dilatation balloon, although there was no significant difference in balloon diameters, balloon length was 90±37 mm and 148±95 mm (P =0.004), and inflation pressure was 11±3 atm and 16±7 atm (P <0.001) in the chocolate PTA and conventional groups, respectively.

Angiographic outcome after pre-dilatation and the rate of bailout stent

In the angiogram after pre-dilatation, severe dissection was observed in 2 (4.2%) and 16 (25%) lesions (P =0.003), %DS was 18±15 and 20±17 (P = 0.409) (Table 2 and Figure 2), and bail-out stent rate was 2.1% (1 lesion) and 15.9% (10 lesions) in the Chocolate PTA and conventional groups, respectively (Table 2 and Figure 2). In the univariate analysis, predictors of a bailout stent were chronic total occlusion (CTO) lesions, lesion length, and non-use of Chocolate PTA balloon (Table 4).

Clinical outcomes

In the Chocolate PTA group, rates of primary patency and freedom from TLR were 89.1% and 85.2%, respectively, at six months; in the conventional group, the rates were 100% and 92.8%, respectively. There were no significant differences between the two groups.

This study is the first to evaluate the impact of Chocolate PTA balloon for vessel preparation with DCB strategy compared to other conventional balloons. This study found that Chocolate PTA balloon had less vessel dissection and sufficient expansion than conventional balloon vessel preparation.

In recent years, the development of DCB has resulted in favorable outcomes and has made a substantial contribution to revascularization without stent implantation. Tepe et al.[18] demonstrated that compared with conventional balloon angioplasty, DCB was associated with higher primary patency at 12 months in a randomized controlled trial (82.2% vs. 52.4%, p<0.01). However, 7%–12% of patients require provisional stent implantation; therefore, the DCB strategy is essential to obtain sufficient lumen area using uncoated balloon dilatation and to prevent flow-limiting dissection. To achieve successful EVT using DCB strategy, balloon angioplasty must be optimized.

In this study, the frequency of severe angiographic dissection after pre-dilatation was 4.2% in the Chocolate PTA group and 25% in the conventional group (Figure 2). In a study on Chocolate PTA balloon,[11] the incidence of type C or higher dissection was reported to be 11.1%. Although it was not possible to make a direct comparison, the results were comparable to those of this study. IVUS findings showed a similar minimum lumen area in both groups after pre-dilatation, but the incidence of dissection above 180° was lower in the Chocolate PTA balloon group (Table 3).

A previous report[10] reported the incidence of severe dissection to be 42%, and its predictors were reference vessel diameter <5 mm, lesion length >15 cm, and CTO lesion. As shown in Table 1, there were no significant differences in the lesion characteristics of reference diameter, lesion length, and the ratio of CTO in this study. It is possible that the effect of the Chocolate PTA balloon could prevent the occurrence of severe dissection.

There are several reasons for this effect. First, Chocolate PTA balloon is a novel, semi-compliant balloon catheter aimed at less traumatic percutaneous transluminal angioplasty.[19,20] The concept of this technology is to deliver controlled dilatation of vessels, resulting in successful angioplasty without dissection. Chocolate PTA balloon is a balloon constrained by a mounted nitinol structure around it, which during inflation, forces the balloon to form several segmented ‘pillows’ and ‘grooves’ along the lesion. The formation of these pillows and grooves resembles a chocolate bar and thus its name. The manufacturers report the following mechanism of action: the balloon-confined inflation prevents ‘dog-boning’ inflation pattern and protects healthy vessel tissue, while simultaneous expansion of the nitinol cage with the balloon protects the vessel from traumatic torsional stress that usually causes dissections. Conversely, the ‘pillows’ contact the vessel wall and apply force to create small dissections, necessary for effective lesion dilatation, while the grooves minimize arterial wall stress and stop the dissections created by them from propagating.

Second, a previous study[21] demonstrated that long balloons covering CTO lesions have less dissection, and this report points out the possibility of dissection at the balloon edge. In this study, the Chocolate PTA balloon group had a shorter balloon length. However, fewer dissections and Chocolate PTA balloon nitinol cage prevent longitudinal balloon elongation, which may reduce edge dissection.

Third, regarding the method of preventing vascular dissection in balloon dilation, a previous study[22] performed super slow inflation that slowly dilated the balloon at low pressure. In this study, the Chocolate PTA balloon uses the method of expansion in the Chocolate Bar registry,[11] which "extends to half nominal in 30 seconds and then increases to nominal pressure". Conversely, the conventional group raises the nominal pressure by approximately 10 s according to the decision of each operator. Although different from the protocol of super slow inflation,[22] slower balloon inflation in the Chocolate PTA group than in the conventional group may be one of the factors that cause less severe dissection.

Another finding of our study is that the use of Chocolate PTA balloon may prevent bailout stents. The rate of bailout stenting in the Chocolate PTA balloon group was 2.1%, which was a low probability in the Chocolate PTA balloon group, considering that it was 15.9% in the conventional group (Figure 2).

Predictors of bailout stents were CTO lesion, longer lesion length, and non-use of Chocolate PTA balloon (Table 4). In a previous study[23] using a Chocolate PTA balloon for vessel preparation before DCB, many complex lesions contained 65.5% CTO lesions and 21.4% of CTOs with lesion length >150 mm. However, the bailout stent rate was 9.5%. Randomized controlled trials comparing bare nitinol stents with plain old balloon angioplasty (POBA) reported a bailout stent frequency of up to 40% in the PTA group.[24,25] In addition, randomized controlled trials comparing DCB and POBA reported that the bailout stent rate was 7.3%–26.7%.[18,26] Although this is a different study and cannot be directly compared, the Chocolate PTA balloon group in this study, even in treating complex lesions (TASC-II C/D 42%, CTO 23%, PACSS 3/4 50%, and lesion length 134±98 mm), has a low rate of bailout stenting.

Relationship between vessel preparation by Chocolate PTA balloon and clinical outcomes

After six months, there were no significant differences between the two groups in the results for both primary patency and freedom from TLR. Our study demonstrated that Chocolate PTA balloon did not improve the primary patency. There is a possible reason for this finding. Because primary patency was investigated in patients with few severe dissections after balloon angioplasty after bailout stenting, it is likely that Chocolate PTA balloon improved immediate procedural success of DCB strategy but was not associated with maintaining the arteries in an open state if severe dissection was absent.

Limitations

This study has several limitations. First, this study was retrospective and included a small number of patients. This study was conducted at a single facility, and the number of available participants was small. Second, grouping according to the period may include potential bias. Third, since there were few cases of bailout stents, the factor can only be investigated by univariate analysis. Thus, it is necessary to increase the number of events and perform a multivariate analysis. There is a need to increase this number. Finally, the observation period was only six months, and the long-term prognosis is unknown. Further investigation is required to clarify the long-term prognosis.

Chocolate PTA balloons can reduce the rate of severe dissection while maintaining a sufficient dilatation effect in DCB vessel preparation compared to conventional balloons.

EVT: endovascular treatment

FP: femoropopliteal

DCB: drug-coated balloon

SFA: superficial femoral artery

PTA: percutaneous transluminal angioplasty

TLR: target-lesion-revascularization

CLTI: chronic limb-threatening ischemia

Fr: French

IVUS: intravascular ultrasound

％DS: percent diameter stenosis

TASC-Ⅱ: Trans-Atlantic Inter-Society Consensus-II

NHLDI: the National Heart, Lung and Blood Institute

CTO: chronic total occlusion

POBA: plain old balloon angioplasty

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Table 1. Patient and lesion characteristics

TASCⅡ, Trans-Atlantic Inter-Society Consensus II; PACSS, Peripheral Arterial Calcium Scoring System; CTO, chronic total occlusion

	Chocolate n=48	Conventional n=63	P
Patient characteristics
Age, years	74±8	74±9	0.900
Male, (%)	36(75)	46(73)	0.814
Body mass index, kg/m²	23.4±4.2	23.2±4.0	0.682
Hypertension, n (%)	43(90)	55(87)	0.711
Dyslipidemia, n (%)	28(58)	32(51)	0.430
Diabetes mellitus, n (%)	31(65)	41(65)	0.957
Chronic kidney disease, n (%)	31(65)	46(73)	0.340
Hemodialysis, n (%)	16(33)	27(43)	0.308
Smoker, n (%)	10(21)	12(19)	0.815
Asprin, n (%)	34(71)	48(76)	0.525
Thienopyridine, n (%)	41(85)	54(86)	0.965
Cilostazol, n (%)	12(25)	10(16)	0.232
Prior Coronary artery disease, n (%)	16(33)	28(44)	0.236
Prior peripheral artery disease, n (%)	22(46)	31(49)	0.725
Prior cerebrovascular disease, n (%)	9(19)	8(13)	0.380
Chronic limb-threatening ischemia, n (%)	10(21)	19(30)	0.268
Lesion characteristics
Pre-ankle brachial index	0.70±0.16	0.65±0.17	0.094
Post-ankle brachial index	0.93±0.15	0.90±0.19	0.744
TASCⅡ C/D, n (%)	20(42)	33(52)	0.263
PACSS 3/4, n (%)	24(50)	33(52)	0.804
include P2/3 lesion, n (%)	14(29)	24(38)	0.326
CTO lesion, n (%)	11(23)	22(35)	0.170
Lesion Length, mm±SD	134±98	156±96	0.116
Vessel diameter, mm±SD	4.7±0.7	4.7±0.9	0.468
poor run off vessel, n (%)	14(29)	24(38)	0.326

Table 2. Procedural and angiographical characteristics

	Chocolate n=48	Conventional n=63	P
Procedural characteristics
Pre-balloon dilatation
Balloon diameter, mm	4.8±0.8	4.6±0.8	0.156
Balloon length, mm	90±37	148±95	0.004
Inflation pressure, atm	11±3	16±7	<0.001
Inflation time, sec	154±42	132±77	0.225
Final device
Drug-coated balloon, n (%)	47(98)	53(84)	0.016
Bailout stent, n (%)	1(2.1)	10(15.9)	0.016
Angiographical results
Post pre-dilatation
Dissection grade
Grade none, n (%)	29(60)	18(29)	0.006
Grade A, n (%)	14(29)	19(30)
Grade B, n (%)	3(6)	10(16)
Grade C, n (%)	1(2)	8(13)
Grade D, n (%)	1(2)	7(11)
Grade E or F, n (%)	0	1(2)
Severe dissection, n (%)	2(4.2)	16(25.4)	0.003
%Diameter stenosis, %	18±15	20±17	0.409
Final angiogram
%diameter stenosis, %	13±11	13±12	0.990

Table 3. IVUS parameters

EEM, external elastic membrane; CSA, cross sectional area; IVUS, intravascular ultrasound.

IVUS parameters	Chocolate n=48	Conventional n=63	P
Distal reference
Reference diameter, mm	5.1±0.8	5.1±0.8	0.621
Distal EEM CSA, mm²	20±7	21±7	0.394
Distal lumen CSA mm²	15±7	15±6	0.916
Post pre-dilatation
Dissection ≥180°, n (%)	2(6)	11(22)	0.014
Minimum lumen area, mm²	11.4±3.7	12.1±4.9	0.701

Table 4. Logistic regression analysis of bailout stent

OR: odds ratio, CI: confidence interval.

Variables	Univariate analysis OR 95% CI P value
Chronic total occlusion	10.8	2.8-42.1	0.001
Lesion length (per 10-mm increase)	1.08	1.02-1.15	0.045
Vessel diameter (per 1-mm increase)	1.22	0.58-2.59	0.605
Non-use of Chocolate PTA balloon (vs Conventional)	8.9	1.1-71.9	0.009

Impact of Chocolate percutaneous transluminal angioplasty balloon on vessel preparation in drug-coated balloon angioplasty for femoropopliteal lesion

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Abstract

Figures

Introduction

Materials and Methods

Results

Discussion

Conclusion

abbreviations

References

Tables

Status:

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