Device selection in the treatment of in-stent restenosis with and without radiation (from the Gamma Radiation Trials)

Is Complete Revascularisation Mandated for all Patients with Multivessel Coronary Artery Disease?

In multivessel coronary artery disease (MVCAD), myocardial revascularisation can be achieved by percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG), with complete revascularisation on all diseased coronary segments or with incomplete revascularisation on selectively targeted lesions. Complete revascularisation confers a long-term prognostic benefit, but is associated with a higher rate of periprocedural events compared with incomplete revascularisation. In most patients with MVCAD, the main advantage of CABG over PCI is conferred by the achievement of more extensive revascularisation. According to current international guidelines, PCI is generally preferred in single-vessel disease, low-risk MVCAD or isolated left main disease; whereas CABG is usually recommended in patients with complex two-vessel disease, most patients with three-vessel disease and/or non-isolated left main disease. In patients with MVCAD, the choice on revascularisation modality should depend on a multifactorial evaluation, taking into account not only coronary anatomy, the ischaemic burden, myocardial function, age and the presence of comorbidities, but also the adequacy of myocardial revascularisation.

Rotational atherectomy: a "survivor" in the drug-eluting stent era

Mechanical debulking of coronary plaques with rotational atherectomy (RA) has been used for more than 20 years during percutaneous coronary interventions (PCI). Modification of plaque characteristics may be accomplished with selective ablation of inelastic fibrocalcific tissue. The use of RA, though reduced with the development of bare-metal stents (BMS) and even more with drug-eluting stents (DES), has never been completely abandoned. The present review will analyze reasons for conflicting results obtained in large series and randomized trials on this topic in the past, and will identify criteria for an appropriate use in current times.

Clinical outcome of patients undergoing low aggressive angioplasty combined with brachytherapy and short-term dual antiplatelet therapy for in-stent restenosis

OBJECTIVE

The impact of vessel injury on the outcome of patients undergoing percutaneous coronary intervention combined with brachytherapy for in-stent restenosis is under investigation. We report our clinical experience adopting a low aggressive balloon angioplasty technique, to limit vessel trauma, associated with brachytherapy and short-term dual antiplatelet therapy.

METHODS

Forty-nine consecutive patients, undergoing percutaneous coronary intervention with brachytherapy for symptomatic in-stent restenosis, were prospectively observed for a median time of 21 + or - 8 months. Clinical follow-up included anginal status, death, myocardial infarction and repeat revascularization; only patients with evidence of ischaemia repeated coronary angiography. Low aggressive angioplasty consisted in the use of a conventional balloon with a balloon to artery ratio < or = 1, avoiding high inflation pressures and the use of other devices. Dual antiplatelet therapy was continued for 3-6 months.

RESULTS

Early angiographic result was good and the need for additional stent implantation was low (3.9%). At follow-up, we did not observe death, acute myocardial infarction or stent thrombosis, but 10 patients repeated coronary angiography for recurrence of ischaemia: disease progression was present in two cases (4.1%). Restenosis emerged in the remaining eight patients (16.3%): two cases showed restenosis within the target lesion segment, one case within the injured segment, one case within the radiated segment, and four cases at the edges. The consequent new revascularization was surgical in three patients and percutaneous in seven patients.

CONCLUSIONS

Our data suggest that low aggressive angioplasty followed by brachytherapy and short-term dual antiplatelet therapy for in-stent restenosis is related to a good outcome, with a low restenosis rate and without stent thrombosis.

Comparison of angiographic and clinical outcomes between rotational atherectomy and cutting balloon angioplasty followed by radiation therapy with a rhenium 188-mercaptoacetyltriglycine-filled balloon in the treatment of diffuse in-stent restenosis

BACKGROUND

Rotational atherectomy (RA) and cutting balloon angioplasty (CBA) have been shown to effectively dilate in-stent restenosis (ISR). It is not known, however, which of these technique, when followed by beta-radiation, is more effective. Therefore, we performed a prospective randomized study comparing RA and CBA before beta-radiation therapy for diffuse ISR.

METHODS

Patients with diffuse ISR were randomly assigned to receive RA (group 1, n = 58) or CBA (group 2, n = 55) before beta-radiation therapy with a rhenium 188-mercaptoacetyltriglycine-filled balloon, with the radiation dose being 18 Gy at a depth of 1.0 mm into the vessel wall. The primary end point was angiographic restenosis at 6 months, and the secondary end point was major adverse cardiac events (myocardial infarction, death, target lesion revascularization) at 9 months.

RESULTS

The 2 groups were similar in baseline characteristics. Mean lesion length was 21.0 +/- 11.2 mm in group 1 and 20.8 +/- 10.2 mm in group 2 (P = .77). Radiation was delivered successfully to all patients. We obtained 6-month angiographic follow-up in 90 patients (80%). The rates of angiographic restenosis were 14.9% (7 of 47) in group 1 and 14.0% (6 of 43) in group 2 (P = .89). No patient experienced myocardial infarction or death during the 9-month follow-up period. Rates of target lesion revascularization or major adverse cardiac events were 3.4% in group 1 and 3.6% in group 2 (P = .94) during the 9-month follow-up.

CONCLUSIONS

Either RA or CBA, followed by beta-radiation using a rhenium 188-mercaptoacetyltriglycine-filled balloon, is equally safe and effective for diffuse ISR in 6-month angiographic and 9-month clinical outcomes.

Comparison of angiographic and clinical outcomes between rotational atherectomy versus balloon angioplasty followed by radiation therapy with a rhenium-188-mercaptoacetyltriglycine-filled balloon in the treatment of diffuse in-stent restenosis

BACKGROUND

The purpose of this study was to compare the efficacy of rotational atherectomy (RA) with simple balloon angioplasty, prior to beta-radiation therapy with a rhenium-188-mercaptoacetyltriglycine (188Re-MAG3)-filled balloon for diffuse in-stent restenosis (ISR).

METHODS

After completing 50 cases with RA prior to beta-radiation (Group I), we performed optimal balloon angioplasty followed by beta-radiation in the next 53 consecutive patients (Group II) for the treatment of diffuse ISR. The radiation dose was 15 Gy at a depth of 1.0 mm into the vessel wall.

RESULTS

The baseline clinical and angiographic characteristics were similar between the two groups. The mean length of the lesion was 25.6+/-12.7 mm in Group I and 22.9+/-8.6 mm in Group II (p=0.26). Radiation was successfully delivered to all patients, with a mean irradiation time of 179+/-55 s. The 6-month angiographic restenosis rate was 10% (5/50) in Group I versus 33% (17/51) in Group II (p=0.007). No adverse event including myocardial infarction, death, or stent thrombosis occurred during the 1-year follow-up period. The risk of a target lesion revascularization or a major adverse cardiac event was significantly lower in Group I than in Group II (two patients in Group I vs. nine patients in Group II; OR, 0.20; 95% CI, 0.04-0.96; p=0.04).

CONCLUSION

Concomitant treatment with rotational atherectomy and beta-irradiation using a 188Re-MAG3-filled balloon for diffuse ISR has a synergistic effect, in terms of 6-month angiographic restenosis and 1-year cardiac event-free survival.

Axillo-axillary bypass for in-stent restenosis in Takayasu arteritis

We report a patient with Takayasu arteritis (TA) who initially received stent placement (SP) following percutaneous transluminal balloon angioplasty for stenotic lesion of the left subclavian artery and subsequently had recurrent in-stent restenosis three times. Every time restenosis occurred, percutaneous transluminal rotational arterectomy (RA) was performed. After all, the patient underwent axillo-axillary bypass and has remained asymptomatic for 10 months after the surgery. We suggest that surgical treatment is beneficial for in-stent restenosis in patient with Takayasu arteritis.

Five-Year Follow-Up After Intracoronary Gamma Radiation Therapy for In-Stent Restenosis

Background— The Washington Radiation for In-Stent Restenosis Trial is a double-blinded randomized study evaluating the effects of intracoronary radiation therapy (IRT) in patients with in-stent restenosis (ISR).

Methods and Results— One hundred thirty patients with ISR (100 native coronary and 30 vein grafts) underwent percutaneous transluminal coronary angioplasty, laser ablation, rotational atherectomy, or additional stenting (36% of lesions). Patients were randomized to either 192-Iridium IRT or placebo, with a prescribed dose of 15 Gy to a 2-mm radial distance from the center of the source. Angiographic restenosis (27% versus 56%, P =0.002) and target vessel revascularization (26% versus 68%, P <0.001) were reduced at 6 months in patients treated with IRT. Between 6 and 60 months, patients treated with IRT compared with placebo had more target lesion revascularization (IRT, 21.6% versus placebo, 4.7%; P =0.04) and target vessel revascularization (IRT, 21.5% versus placebo, 6.1%; P =0.03). At 5 years, the major adverse cardiac event rate was significantly reduced with IRT (46.2% versus 69.2%, P =0.008).

Conclusions— In the Washington Radiation for In-Stent Restenosis Trial, patients with ISR treated with IRT using 192-Iridium had a reduction in the need for repeat target lesion and vessel revascularization at 6 months and 5 years.

Real-world clinical practice of intracoronary radiation therapy as compared to investigational trials

Intracoronary radiation therapy (IRT) is well established in clinical practice as an effective treatment for in-stent restenosis. We aimed to determine if the 6-month clinical outcome of patients treated postapproval for marketing [commercial radiation (CR)] is equivalent to those patients enrolled in the Washington Radiation for In-Stent Restenosis Trials [Gamma WRIST and Beta WRIST; investigational radiation (IR)]. The 6-month clinical outcome of 110 consecutive patients with 125 lesions who received IRT (gamma, (192)Ir, 15-18 Gy, n = 6; or beta, (32)P, 20 Gy, n = 20; or (90)Sr/Y, 18.4-23.0 Gy, n = 99) in CR was compared with the 6-month clinical outcome of 117 patients with 117 lesions who received IRT ((192)Ir, 15 Gy, n = 65, in Gamma WRIST; and (90)Y, 20.6 Gy, n = 52, in Beta WRIST) in IR. Patients in CR were treated with wider radiation margins. The CR received antiplatelet therapy for at least 6 months and the IR for 1 month. The baseline characteristics of both groups were similar. Use of atheroablation devices was less in CR than IR (15.2% vs. 32.8%, respectively; P = 0.001). The overall major adverse cardiac events (death, Q-wave myocardial infarction, and target vessel revascularization; 18.2% vs. 29.1% in IR; P = 0.05) were significantly lower in the CR when compared with patients in the IR. The real-world clinical practice of IRT demonstrates lower events and better clinical outcomes. This is most likely a result of implementation of the lessons learned from the clinical trials such as optimizing the dosimetry by using a higher dose, treating wider margins to minimize edge effect, and administering prolonged antiplatelet therapy to abolish late thrombosis.

Usefulness of the angiographic pattern of in-stent restenosis in predicting the success of gamma vascular brachytherapy

The prognostic role of the angiographic pattern of in-stent restenosis after gamma vascular brachytherapy was assessed from a pooled data set of 4 clinical trials comprising 295 irradiated patients with matched baseline and follow-up angiograms. The binary angiographic restenosis rate increased with worsening in-stent restenosis patterns; however, target lesion revascularization and major adverse cardiac event rates increased for focal, diffuse, and proliferative patterns of in-stent restenosis but not for total occlusions.

Additional stenting promotes intimal proliferation and compromises the results of intravascular radiation therapy: an intravascular ultrasound study

BACKGROUND

Vascular brachytherapy (VBT) reduces in-stent restenosis (ISR). However, additional stenting at the time of radiation may be associated with a worse outcome.

METHODS AND RESULTS

Intravascular ultrasound (IVUS) was performed after VBT and at 6 months follow-up in 79 native artery ISR patients treated with gamma-radiation who participated in the Washington Radiation for In-Stent restenosis Trial (WRIST), Gamma-1, and Angiorad Radiation Technology for In-Stent restenosis Trial in Coronaries (ARTISTIC) trials. Patients were treated with (192)Ir at 14 or 15 Gy at 2 mm from the source. Additional stents were used to treat the ISR lesions in 45 patients; these patients were then compared with the 34 patients treated without restenting. Paired measurements included stent, lumen, and intimal hyperplasia volumes. After the VBT procedure, intimal hyperplasia volume was smaller in the group treated with additional stents (54 +/- 33 mm(3) vs 34 +/- 33 mm(3), P =.012), but minimal lumen area was similar between the 2 groups (4.3 +/- 1.5 mm(2) vs 4.7 +/- 1.4 mm(2) respectively, P = NS). Between the time of the VBT procedure and follow-up, intimal hyperplasia volume increased by 27 +/- 19 mm(3) in the restented group and by 9 +/- 21 mm(3) in the group treated without additional stents (P =.014). At 6 months, intimal volume was similar in the 2 groups, but minimal lumen area was slightly smaller in the group treated with additional stents (3.4 +/- 1.8 mm(2) vs 4.2 +/- 1.7 mm(2), P =.053). Patients treated with additional stents had more target lesion revascularizations than the group treated without additional stents (38% vs 15%, P =.02).

CONCLUSIONS

Additional stenting reduces intimal hyperplasia within the stents acutely. However, it compromises the benefit of VBT by promoting higher intimal regrowth within months after radiation.

Intracoronary radiation therapy improves the clinical and angiographic outcomes of diffuse in-stent restenotic lesions: results of the Washington Radiation for In-Stent Restenosis Trial for Long Lesions (Long WRIST) Studies

BACKGROUND

The Washington Radiation for In-Stent Restenosis Trial for long lesions (Long WRIST) was designed to determine the safety and efficacy of vascular brachytherapy for the treatment of diffuse in-stent restenosis.

METHODS AND RESULTS

A total of 120 patients with diffuse in-stent restenosis in native coronary arteries (lesion length, 36 to 80 mm) were randomized for either radiation with 192Ir with 15 Gy at 2 mm from the source axis or placebo. After enrollment, 120 additional patients with the same inclusion criteria were treated with 192Ir with 18 Gy and included in the Long WRIST High Dose registry. Antiplatelet therapy was initially prescribed for 1 month and was extended to 6 months in the last 60 patients of the Long WRIST High Dose registry. At 6 months, the binary angiographic restenosis rate was 73%, 45%, and 38% in the placebo, 15 Gy, and 18 Gy radiated groups, respectively (P<0.05). At 1 year, the primary clinical end point of major cardiac events was 63% in the placebo group and 42% in the radiated group with 15 Gy (P<0.05). The major cardiac event rate was further reduced with 18 Gy (22%; P<0.05 versus 15 Gy). Late thrombosis was 12%, 15%, and 9% in the placebo group, 15 Gy group with 1 month of antiplatelet therapy, and 18 Gy group with 6 months of antiplatelet therapy, respectively.

CONCLUSIONS

Vascular brachytherapy with 192Ir is safe and reduces the rate of recurrent restenosis in diffuse in-stent restenosis. The efficacy of vascular brachytherapy on angiographic and clinical outcomes is enhanced with a radiation dose of 18 Gy and prolonged antiplatelet therapy.

Debulking does not benefit patients undergoing intracoronary beta-radiation therapy for in-stent restenosis: insights from the START trial

Intracoronary brachytherapy has become the current treatment of choice for patients with in-stent restenosis (ISR). The aim of the present study was to determine whether plaque extraction using debulking techniques prior to brachytherapy would improve the outcomes of patients with ISR. Patients enrolled into the START (n = 476) and START-40 (n = 205) trials were divided into four subgroups according to their treatment assignments: debulking-radiation, debulking-placebo, balloon angioplasty (BA) radiation, and BA placebo. Patients were further divided according to their ISR lesion length: all lesions, > 15 mm, and > 19 mm. Restenosis rates were higher in placebo, nonradiated lesions undergoing debulking (52.7%) vs. BA alone (38.5%; P = 0.04). Postprocedural minimal lumen diameter (MLD) was similar among the subgroups. Outcomes were similar between debulking and BA within each therapeutic arm. MLD after debulking radiation was greater in patients with ISR > 15 mm (post-MLD was 1.9 vs. 1.7 mm; P = 0.06) but not in the placebo. Debulking radiation patients had greater MLD at follow-up, but restenosis (23.5% after debulking vs. 32.7% BA alone) and late loss (0.3 mm in both subgroups) were not statistically different. There was a trend toward higher mortality among debulked patients (3.7%) compared to BA alone (0.8%). In patients with ISR > 19 mm, four patients died following debulking radiation as compared to no death after BA (P = 0.05). Our results do not support the strategy of plaque extraction prior to intracoronary beta-radiation for ISR.

The outcome of percutaneous coronary intervention in patients with in-stent restenosis who failed intracoronary radiation therapy

OBJECTIVES

This study reports the outcome of patients who failed intracoronary radiation therapy (IRT) for the treatment of in-stent restenosis (ISR).

BACKGROUND

Intracoronary radiation therapy has demonstrated a reduction in the recurrence rate of restenosis for patients with ISR. However, 10% to 30% of these patients require repeat intervention to the irradiated site.

METHODS

Of 961 patients who were assigned to gamma or beta radiation for the treatment of diffuse ISR, we evaluated the outcome of 282 (29%) consecutive patients who failed IRT and compared them with the 679 (71%) patients who had successful IRT. For patients who failed radiation, the mean time to the first target vessel revascularization (TVR) was 173 +/- 127 days after the index procedure and the total duration of follow-up was 494 +/- 304 days.

RESULTS

Patients who failed IRT were younger (60 +/- 10 vs. 63 +/- 11 years, p = 0.002) and had a higher incidence of restenting (51% vs. 41%, p = 0.003). The majority (55%) of the restenotic lesions after IRT failure were focal (< or =10 mm), with a mean lesion length of 11.9 +/- 1.9 mm. Of the 257 patients who had subsequent TVR after failed IRT, 68 (26%) underwent coronary artery bypass grafting and 189 (74%) underwent percutaneous coronary intervention using balloon in 61%, restenting in 26%, atheroablation in 11%, and the cutting balloon in 2% of cases. At six months, 6% of patients died, 1% had Q-wave MI, 17% had repeat TVR, and the overall rate of major adverse cardiac events was 21%.

CONCLUSIONS

The predominant angiographic pattern of lesions in patients who failed IRT is focal restenosis, with these lesions responding well to conventional revascularization methods.

Impact of intracoronary radiation on in-stent restenosis involving ostial lesions

The aim of this study was to compare 6-month clinical outcomes of patients with in-stent restenosis (ISR) involving the ostium treated with intracoronary radiation therapy (IRT) compared to placebo therapy, and also to nonostial lesions treated with IRT. Coronary interventions in ostial lesions have a high rate of recurrence of restenosis. The impact of IRT on ostial ISR has been inadequately characterized. We assessed patients enrolled in gamma (192-iridium) and beta (90-yttrium, 32-phosphorus) radiation trials for ISR at the Washington Hospital Center. Of patients receiving IRT, 105 (8%) patients had ostial ISR and 1,289 (92%) patients had nonostial ISR. Twenty-seven patients had ostial ISR and received placebo therapy. Baseline demographic and angiographic and procedural details were similar, except ostial IRT patients had a trend toward shorter lesions (15.4 +/- 10.8 vs. 24.1 +/- 12.2 mm; P < 0.001) and had a higher rate of saphenous vein graft disease (46% vs. 19%; P < 0.001) compared to nonostial IRT patients. At 6 months, ostial lesions treated with IRT for ISR had a reduced rate of target lesion revascularization (TLR) compared to ostial lesions treated with placebo (15% vs. 43%; P = 0.004). Outcomes at 6 months were similar for the ostial and nonostial IRT groups including TLR (15% vs. 14%; P = 0.80) and composite major adverse cardiac events (18% vs. 15%; P = 0.46). Intracoronary radiation therapy is effective for ostial in-stent restenotic lesions and should be comfortably used for this challenging anatomic location.

Comparison of intracoronary gamma radiation for in-stent restenosis in saphenous vein grafts versus native coronary arteries

Intracoronary gamma radiation is effective in reducing recurrent in-stent restenosis (ISR) involving native coronary arteries. This study compares the effectiveness and safety of intracoronary gamma radiation for the treatment of ISR in saphenous vein grafts (SVGs) versus native coronary arteries. In the Washington Radiation for In-Stent restenosis Trial (WRIST) series of gamma radiation trials, 1,142 patients with ISR (230 in SVG and 912 in native coronary arteries) completed 6-month clinical follow-up. All patients underwent balloon angioplasty, atherectomy, and/or restenting. Different ribbon lengths containing 6 to 23 seeds of iridium-192 were used to cover lesion lengths <80 mm. The prescribed radiation doses were 14 or 15 Gy at 2-mm radial distance from the center of the source. Baseline demographics showed that patients with SVGs were older (65 +/- 13 vs 61 +/- 11 years, p <0.001), more likely male (79% vs 64%, p <0.001), had more multivessel coronary disease (81% vs 50%, p <0.001), and less diffuse lesions (17 +/- 10 vs 24 +/- 12 mm, p <0.001). At 6 months, event-free survival was similar for patients with SVG ISR and native coronary ISR (82% vs 84%, p = 0.35). The SVG ISR population had a low rate of late total occlusion (4.6%) and late thrombosis (3.5%). Thus, treatment of ISR with gamma radiation in SVGs had similar outcome to native coronary arteries. The use of gamma radiation for the treatment of ISR should expand to SVGs.

Three-year follow-up after intracoronary gamma radiation therapy for in-stent restenosis. Original WRIST. Washington Radiation for In-Stent Restenosis Trial

BACKGROUND

The Washington Radiation for In-Stent Restenosis Trial (WRIST) is a double-blinded randomized study evaluating the effects of intracoronary radiation therapy (IRT) in patients with in-stent restenosis (ISR).

METHODS

One hundred and thirty patients with ISR (100 native coronary and 30 vein grafts) underwent PTCA, laser ablation, rotational atherectomy, and/or additional stenting (36% of lesions). Patients were randomized to either Iridium-192 IRT or placebo, with a prescribed dose of 15 Gy to a 2-mm radial distance from the center of the source.

RESULTS

Angiographic restenosis (27% vs. 56%, P=.002) and target vessel revascularization (TVR; 26% vs. 66%, P<.001) were dramatically reduced at 6 months in IRT patients. Between 6 and 36 months, IRT compared to placebo patients had more target lesion revascularization (TLR; IRT=17% vs. placebo=2%, P=.002) and TVR (IRT=17% vs. placebo=3%, P=.009). At 3 years, the major adverse cardiac event (MACE) rate was significantly reduced with IRT (39% vs. 65%, P=.003).

CONCLUSIONS

In WRIST, patients with ISR treated with IRT using 192Ir had a marked reduction in the need for repeat target lesion and vessel revascularization at 6 months, with the clinical benefit maintained at 3 years.