Acute and Mid-term Results of Percutaneous Coronary Intervention for Severely Calcified Coronary Artery Lesions With Orbital Atherectomy System

ABSTRACT

Objectives: Severely calcified lesions present many challenges for percutaneous coronary intervention (PCI). This study aimed to assess the safety and efficacy of the orbital atherectomy system (OAS) in treating calcified coronary lesions.

Methods: The present study included 422 consecutive cases (546 lesions) who underwent PCI with OAS in Kyoto Katsura Hospital from February 2018 to December 2021. We assessed the following clinical outcomes after OAS was used for severely calcified lesions: procedure success, angiographic complications, in-hospital Major Adverse Cardiovascular Events (MACE), and mid-term results. The primary endpoint was the combination of incidence of MACE at 12 months, cardiac death, myocardial infarction (MI), and target lesion revascularization (TLR).

Results: Of all the cases, 74% patients were men and the mean age was 76.5 years. In total, 81% of lesions were treated with drug-coated balloon, and 14% were implanted with stents. Procedural success rate was 96.3%. Coronary perforation occurred in 0.5% and persistent slow flow in 2% lesions. There was 1 cardiac death (0.5%), 43 periprocedural MIs (10.2%), and no TLR as in-hospital MACE. The incidence of MACE at 12 months was 8.4%, including 2.1% cardiac death and 6.9% TLR. In multivariate analysis, CKD, hemodialysis, and restenosis lesions were independently associated with MACE at 12 months. Periprocedural MI was not an independent predictor of MACE.

Conclusions: This study suggested that OAS is a safe and effective treatment option for calcified coronary lesions with acceptable acute and mid-term results; thus, it can be an alternate for reducing calcified plaque.

Key words: calcified lesions, orbital atherectomy, percutaneous coronary intervention

J INVASIVE CARDIOL 2023;35(8). 

BACKGROUND

The prevalence of coronary artery calcification (CAC) is increasing, accounting for 40.2% and 82.7% of all lesions detected by angiography and intravascular ultrasound, respectively.¹ Furthermore, existing CAC increases the complexity of percutaneous coronary intervention (PCI), thereby resulting in complications such as coronary dissection and perforation.² PCI for heavily calcified coronary artery lesions shows higher risk of myocardial infarction (MI), stent thrombosis, repeat revascularization, and death.³ Scoring balloon and rotational atherectomy (RA) are performed to modify the lesions; however, PCI performed on these calcified lesions has inferior results compared to that on noncalcified lesions.⁴ A Diamondback 360 Coronary Orbital atherectomy system (Medikit) has recently become available as the ORBIT II trial investigated the safety and efficacy of the OAS to treat calcified lesions in acute term.⁵ The purpose of this study is to evaluate the acute and mid-term clinical outcomes of patients with calcified coronary artery disease treated with OAS.

METHODS

Study design and population. This retrospective study enrolled 422 consecutive patients who underwent orbital atherectomy for severely calcified coronary lesions between February 2018 and December 2021 at our institute. An OAS was used for lesions with calcified plaque when a guidewire was able to touch the plaque by angiography or imaging device. OAS was used for 14% of all lesions (546 of 3877 lesions). Rotablator and directional coronary atherectomy were administered to 13% and 7% of patients, respectively. PCI was performed after obtaining written informed consent from each patient. Moreover, patient’s clinical, procedural, and angiographic data were analyzed. The coronary lesion type was categorized based on the American Heart Association/American College of Cardiology classification. This study was approved by the research review board of Kyoto Katsura Hospital and was conducted according to Helsinki Declaration.

Procedure. All PCIs were performed with imaging guidance using optical frequency domain imaging (OFDI) or intravascular ultrasound (IVUS) at pre- and post-debulking. The final device (stent or drug-coated balloon [DCB]), antithrombotic therapy, and imaging device, as well as the use of hemodynamic support device and transvenous pacemaker were selected on the operator’s discretion. In the present study, two types of OAS were used: micro crown and classic crown. High-speed atherectomy was applied after low-speed atherectomy when there is no angiographical slow flow and more plaque still remain which can be ablated. When enough lumen was obtained without severe vessel dissection after pre-balloon dilatation, DCB (Sequent Please; B Braun) was used as much as possible.

Quantitative coronary angiography analysis. Quantitative coronary angiography was performed using QAngio XA version 7.3 (MEDIS Medical Imaging System BV) at baseline, at the end of the PCI, and on follow-up after intracoronary nitrate injection. Follow-up coronary angiography was scheduled at 6–8 months after PCI. The minimum lumen diameter (MLD), reference diameter (RD), and % diameter stenosis (%DS) were measured.

Study endpoints and definitions. Primary endpoint was the incidence of major adverse cardiovascular events (MACE) during follow-up periods, defined as the composite of cardiac death, MI, and clinically driven target lesion revascularization (TLR). Cardiac death was defined as any death from a proximate cardiac cause, unwitnessed death and sudden death of unknown cause, and all procedure-related deaths. MI was CK-MB elevation ≥10 times the upper limit of normal with or without new pathologic Q wave on the electrocardiogram.⁶Acute gain was defined as an increase in MLD after intervention; late lumen loss (LLL) as a decrease in MLD on follow-up compared with that at the end of the PCI; restenosis as %DS of ≥50%; and late lumen enlargement (LLE) as negative LLL.

Statistical analysis. T-test was performed to compare continuous variables described as mean ± SD. Pearson chi square or Fisher’s exact test was conducted to compare categorical variables derived by absolute counts. Kaplan-Meier method and log-rank test were used to determine survival curves for time-to-event variables based on all available follow-up data. Multivariable Cox proportional hazards regression was performed to identify independent predictors of MACE. A two-sided P-value of <.05 was considered to indicate statistical significance. All statistical analyses were performed using EZR7, which is for R. Notably, it is a modified version of R commander designed to add statistical functions frequently used in biostatistics.

RESULTS

Clinical characteristics. The baseline characteristics are shown in Table 1. The mean age of patients was 76.5 ± 8.3 years, and the prevalence of diabetes mellitus (45.0%) and HD (14.2%) are high. The characteristics of the lesions are summarized in Table 2. Majority of patients in this study had left anterior descending artery (51.1%) and type B2/C (67.6%) lesions. Of these lesions, 83.5% were de novo and 7.1% were in-stent restenosis with calcium plaque.

Angiographic and procedure characteristics. Procedural details and interventional strategy data are listed in Table 3. Imaging device was performed in all patients, using OFDI/OCT (44.6%). OAS at low and high rotational speeds was performed in 100% and 65.0% of lesions, respectively. Moreover, 11.7% of the lesions required RA because OAS could not pass through the lesion or the lesion needed additional ablation with large barr size of RA. Finally, 81.3% of the lesions were treated using a DCB, and 14.1% with stents.

Angiographic results. The rate of success was indicated by thrombolysis in myocardial infarction flow grade 3 (TIMI3) and residual stenosis <50%); in this study, the success rate was 96.3%. Of all patients, 97.6% achieved TIMI3 at the end of the procedure based on angiography results. Periprocedural complications included perforation (0.5%), persistent slow flow (2.4%), and periprocedural MI (using the SCAI definition) (10.2%) (Table 4).

QCA data and follow-up coronary angiography (CAG) results. QCA data and follow-up CAG data are listed in Table 5. Reference vessel diameter and lesion length were 2.61 mm and 15.7 mm, respectively. Of the 546 lesions, only 358 (66%) were subjected to CAG during follow-up. The mean follow-up duration was 247 days after the initial PCI. LLL was 0.19 ± 0.52 mm. Angiographic restenosis and LLE was observed in 11.5% and 36.0% of the lesions, respectively.

Clinical outcomes. The cumulative incidence of each clinical endpoint is summarized in Figure 1. During the follow-up period after 12 months, 8.4% of patients experienced MACE such as cardiac death (2.1%) and TLR (6.9%); none reported MI.

Predictors of MACE. Independent predictors of MACE are summarized in Table 6. After multivariable analysis, CKD, HD, and restenosis lesion were independent predictors of MACE. Procedure MI was not related to any of the predictors.

DISCUSSION

CAC is associated with a higher risk of TLR and MACE after PCI, even with newer-generation drug-eluting stents (DES).⁸ PCI of calcified lesions have been associated with a worse prognosis compared with that of lesions without calcification.^4,9-11 Adequate plaque modification is vital to the acute procedural success of PCI. Prior to the introduction of OAS, RA was the most common atherectomy device used to modify calcified lesions.

In the ROTAXUS trial which aimed to determine the effect of RA on DES effectiveness of calcified lesions, the success rate of the procedure was higher in the group treated with RA than those who received the standard therapy.¹² Previous studies on DES following RA have shown a TLR rate of 6.8%–11.7%.^12-14 Another study reported results of DES following OAS with a lower rate of TLR at 1 year (5.9%).¹⁵ In the present study, 1-year rate of TLR was 6.9%, which is an acceptable result considering the high prevalence of CKD (59%) and HD (14.2%); the predictors of MACE after PCI with OAS were HD, CKD, and restenosis lesion. In addition, 81.3% of lesions were treated of DCB.

In the present study, PCI were performed with OAS or RA in several patients to modify the calcified plaque. DCB was intentionally used as the final device to ablate the calcium plaques as much as possible. OAS has a shorter rigid part than RA. Thus, OAS is preferred when the vessel size is small and a part of the lesion could be ablated. In contrast, RA is more powerful as it can ablate thick and hard calcium and pass through severe stenosis lesion. Though aggressive ablation is vital for successful PCI of calcified lesion, reflow may not occur, thus avoiding MI. Previous studies demonstrated that MI could predict MACE. In this present study, MI occurred in 10.2% of patients, but it was not associated with the occurrence of MACE.

These findings suggest that the aggressive ablation to reach a large lumen area is especially good treatment for calcified lesions. However, we could not predict slow flow. This study has some limitations. First, this study was retrospective and observational study in a single center with no control group. Second, aspects of the procedures, such as the use of stent and standard or scoring balloon, were decided on the operator’s discretion. The endpoint is judged by intravascular imaging, but it impossible to show clear definition of successful results especially because calcified lesions are complex and decisions were made case by case. Finally, follow-up CAG was performed on each operator’s discretion, which might have biased the incidence of TLR.

CONCLUSION

This study showed an acceptable mid-term clinical result in a large proportion of lesions treated by DCB. OAS has high success rate and low restenosis rate, making it an alternative method to reduce calcified plaque.

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