Key Learnings From the JETSTREAM Atherectomy Calcium Study
Insights from the authors on removing severe superficial calcium to achieve significant luminal gain in femoropopliteal arteries.
The recently published JETSTREAM Calcium Study was a prospective, single-arm, multicenter study to evaluate the effect of the JETSTREAM™ Atherectomy System (Boston Scientific Corporation) when treating severely calcified peripheral arterial lesions in the common femoral, superficial femoral, or popliteal arteries causing claudication.1 The main question was whether the JETSTREAM Atherectomy System was effective in removing calcification. This was evaluated using both quantitative and qualitative intravascular ultrasound (IVUS), by comparing preintervention and postatherectomy IVUS images. The two major findings were as follows: The JETSTREAM Atherectomy System removed and modified moderate to severe superficial calcium to achieve significant lumen gain as standalone therapy; and adjunctive balloon angioplasty after calcium modification with the JETSTREAM Atherectomy System showed further lumen increase without major complications. In this study, the JETSTREAM 2.1/3.0 mm device was used for all procedures without distal protection. There were no major adverse events up to 30 days postprocedure.
Case Study 1: Common Femoral*
WHY an IVUS Study is Unique
Calcium was screened by angiography to identify moderate to severe obstructive intraluminal calcification in the common femoral, superficial femoral, or popliteal arteries. Lesions were evaluated by IVUS. Patients identified by angiography as possible candidates were included in the final analysis only if there was superficial calcium that had an arc > 90° and a length > 5 mm. Overall, 55 patients were screened; however, only 26 patients met the inclusion criteria. Half of the lesions identified angiographically as having moderate to severe calcification did not have severe superficial calcium (calcium within the lumen) at the lesion site as determined by IVUS. In these lesions, superficial calcification existed only in nonstenotic segments, or only deep calcification (calcium within the vessel wall) was present at the stenosis site. Therefore, the first finding of this study was the limitation of peripheral angiography to detect and localize calcification in peripheral arterial lesions. Deep calcification may not affect luminal gain (ie, create a stenosis). Therefore, the differentiation between superficial and deep calcification and their respective roles in severe stenosis is important when evaluating the true efficacy of any atherectomy procedure and device. These findings are similar to the data reported by Mintz et al in coronary artery lesions.2 In that study, IVUS detected calcium in 841 of 1,155 coronary artery lesions (73%), while angiography detected calcium in only 440 (38%). Therefore, the overall sensitivity of angiography relative to IVUS was 48%, with a specificity of 89%.
Significant LUMINAL GAIN achieved with jetstream Atherectomy
For the patients who were ultimately included in the study, first the preintervention and postatherectomy IVUS lumens were outlined. Second, the postatherectomy IVUS images were overlaid onto their respective preintervention images. Assuming there was no change in total arterial area, the change in lumen area was attributed to either calcified plaque or noncalcified plaque removal (Figure 3). At the slice with the maximum calcium reduction, the lumen area increased from 6.6 ± 3.7 mm2 preintervention to 10 ± 3.6 mm2 (P = .001) after atherectomy. The decrease in calcium area, measured as 2.8 ± 1.6 mm2, was responsible for 86% ± 23% of the lumen area increase. Additionally, the arc of reverberations increased from 25˚ (range, 15˚–35˚) to 70˚ (range, 46˚–95˚), P = .001, indicating device-related modification of calcium. Therefore, the second lesson was that the JETSTREAM Atherectomy System increased lumen dimensions by calcium removal as well as by calcium modification (increase in reverberations).
Case Study 2: Distal SFA/Proximal Popliteal*
VESSEL EXPANSION WITHOUT VESSEL DAMAGE
In the 11 lesions that had postadjunctive balloon IVUS images, the minimum lumen area increased further from 7 mm2 (range, 6.4–7.8 mm2) after atherectomy to 11.9 mm2 (range, 10.3–13.5 mm2) after adjunct balloon inflation (P < .01). However, the prevalence of dissections also increased from 3/11 after atherectomy to 8/11 after adjunct balloon inflations (P = .03). However, the maximum angle of the dissection flap was minor (42° [range, 17°–66°]) with a preserved lumen area (15.6 mm2 [range, 13.4–17.7 mm2]) within the dissection. The dissections were non-flow limiting. Also, the higher resolution of IVUS imaging versus angiography most likely led to a higher detection rate. Thus, the third and final lesson was that the JETSTREAM Atherectomy System allowed additional lumen increase by facilitating vessel expansion without significant vessel damage (ie, dissection), presumably because of calcium modification. A representative case is shown in Figure 4.
Severely calcified lesions may cause damage to the polymer/drug coating of a drug-eluting stent, resulting in inadequate drug delivery.3,4 Although there is accumulating evidence in coronary artery intervention showing that calcified lesions have worse outcomes compared to noncalcified lesions,5,6 the clinical impact of superficial calcium removal in peripheral artery disease in respect to effectiveness of drug-coated balloons or drug-eluting stents needs further investigation.7
Akiko Maehara, MD, is with Columbia University Medical Center and the Cardiovascular Research Foundation in New York, New York. Dr. Maehara has disclosed that she receives a grant from and is a consultant to, Boston Scientific Corporation.
Gary S. Mintz, MD, is with the Cardiovascular Research Foundation in New York, New York. Dr. Mintz has disclosed that he receives grant support and is a consultant for Boston Scientific Corporation and Volcano Corporation.
William A. Gray, MD, is with Columbia University Medical Center in New York, New York. He has disclosed that he is a consultant to Boston Scientific Corporation. Dr. Gray may be reached at (212) 304-5697; email@example.com.
Acknowledgement: The authors thank investigators Thomas M. Shimshak, MD; Joseph J. Ricotta II, MD, MS; Venkatesh Ramaiah, MD; Malcolm T. Foster III, MD; and Thomas P. Davis, MD, for their work on the JETSTREAM Calcium Study.
1. Maehara A, Mintz GS, Shimshak TM, et al. Intravascular ultrasound evaluation of JETSTREAM atherectomy removal of superficial calcium in peripheral arteries. EuroIntervention. 2015;11:96-103.
2. Mintz GS, Popma JJ, Pichard AD, et al. Patterns of calcification in coronary artery disease. A statistical analysis of intravascular ultrasound and coronary angiography in 1155 lesions. Circulation. 1995;91:1959-1965.
3. Hwang CW, Edelman ER. Arterial ultrastructure influences transport of locally delivered drugs. Circ Res. 2002;90:826-832.
4. Kuriyama N, Kobayashi Y, Yamaguchi M, et al. Usefulness of rotational atherectomy in preventing polymer damage of everolimus-eluting stent in calcified coronary artery. JACC Cardiovasc Interv. 2011;4:588-589.
5. Généreux P, Madhavan MV, Mintz GS, et al. Ischemic outcomes after coronary intervention of calcified vessels in acute coronary syndromes. Pooled analysis from the HORIZONS-AMI (Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction) and ACUITY (Acute Catheterization and Urgent Intervention Triage Strategy) TRIALS. J Am Coll Cardiol. 2014;63:1845-1854.
6. Bourantas CV, Zhang YJ, Garg S, et al. Prognostic implications of coronary calcification in patients with obstructive coronary artery disease treated by percutaneous coronary intervention: a patient-level pooled analysis of 7 contemporary stent trials. Heart. 2014;100:1158-1164.
7. Siablis D, Kitrou PM, Spiliopoulos S, et al. Paclitaxel-coated balloon angioplasty versus drug-eluting stenting for the treatment of infrapopliteal long-segment arterial occlusive disease: the IDEAS randomized controlled trial. JACC Cardiovasc Interv. 2014;7:1048-1056.
*Results from case studies are not necessarily predictive of results in other cases. Results in other cases may vary.