Interventional Options for Coronary Artery Calcification

Management Considerations for Acute Coronary Syndromes in Chronic Kidney Disease

PURPOSE OF REVIEW

Propensity of patients with chronic kidney disease (CKD) to adverse outcomes of acute coronary syndromes (ACS) derives, in part, from imperfection in management. Dearth of data resulting from underrepresentation of patients with CKD in ACS trials and underuse of evidence-based testing and therapy compound biological risks inherent to CKD. We sought in this narrative review to critically appraise contemporary evidence and offer suggested approaches to practicing clinicians for the optimization of ACS management in patients with CKD.

RECENT FINDINGS

Updated multisociety chest pain guidelines emphasize the diversity of clinical presentations of ACS, pertinent to recognition of ACS in patients with CKD. Evolving tools to predict and prevent acute kidney injury complicating invasive management of ACS serve to support improved access to and safety of percutaneous coronary intervention (PCI) in CKD patients, who remain at elevated risk. Growth in use of radial access, advances in PCI quality, incorporation of intravascular imaging, and new options and insights in pharmacotherapy contribute to an evolving calculus of ischemic and bleeding risk in ACS with bearing on management in CKD patients. Key opportunities to improve outcomes of ACS for patients with CKD center on avoiding underuse of beneficial medical and invasive therapies; enhancing safety of therapies by leveraging evidence-based strategies to prevent acute kidney injury; and devoting specific effort to investigation of ACS management in the context of CKD.

Feasibility of in vitro calcification plaque disruption using ultrasound-induced microbubble inertial cavitation

Percutaneous transluminal coronary angioplasty (PTCA) is a clinical method in which plaque-narrowed arteries are widened by inflating an intravascular balloon catheter. However, PTCA remains challenging to apply in calcified plaques since the high pressure required for achieving a therapeutic outcome can result in balloon rupture, vessel rupture, and intimal dissection. To address the problem with PTCA, we hypothesized that a calcified plaque can be disrupted by microbubbles (MBs) inertial cavitation induced by ultrasound (US). This study proposed a columnar US transducer with a novel design to generate inertial cavitation at the lesion site. Experiments were carried out using tubular calcification phantom to mimic calcified plaques. After different parameters of US + MBs treatment (four types of MBs concentration, five types of cycle number, and three types of insonication duration; n = 4 in each group), inflation experiments were performed to examine the efficacy of cavitation for a clinically used balloon catheter. Finally, micro-CT was used to investigate changes in the internal structure of the tubular plaster phantoms. The inflation threshold of the untreated tubular plaster phantoms was > 11 atm, and this was significantly reduced to 7.4 ± 0.7 atm (p = 5.2E-08) using US-induced MBs inertial cavitation at a treatment duration of 20 min with an acoustic pressure of 214 kPa, an MBs concentration of 4.0 × 108 MBs/mL, a cycle number of 100 cycles, and a pulse repetition frequency of 100 Hz. Moreover, micro-CT revealed internal damage in the tubular calcification phantom, demonstrating that US-induced MBs inertial cavitation can effectively disrupt calcified plaques and reduce the inflation threshold of PTCA. The ex vivo histopathology results showed that the endothelium of pig blood vessels remained intact after the treatment. In summary, the results show that US-induced MBs inertial cavitation can markedly reduce the inflation threshold in PTCA without damaging blood vessel endothelia, indicating the potential of the proposed treatment method.

Intravascular lithotripsy for severe coronary calcification: a systematic review

INTRODUCTION

Coronary artery calcification remains a challenge in percutaneous coronary interventions, due to the higher risk of suboptimal result with subsequent poor clinical outcomes. Intravascular lithotripsy is a novel way of treating severe coronary calcification as it has the ability to modify calcium both circumferentially as well as transmurally, facilitating stent expansion and apposition. We conducted a systematic overview of the published literature on intravascular lithotripsy (IVL) assessing the efficacy and feasibility of IVL in treating severe coronary calcification.

EVIDENCE ACQUISITION

Of the retrieved publications, 62 met our inclusion criteria and were included. A total of 1389 patients (1414 lesions) with significant coronary calcification or under-expanded stents underwent IVL.

EVIDENCE SYNTHESIS

The mean age was 72.03 years (74.7% male). There was a significant improvement in acute and sustained vessel patency, with mean minimal lumen diameter of 2.78±0.46 mm, resulting in acute gain of 1.72±0.51 mm. The acute procedural success rate was 78.2 to 100% with in-hospital complication rate of 5.6 to 7.0%. The majority of the studies reported 30-day MACE, which was between 2.2 to 7.8%.

CONCLUSIONS

The recent studies have highlighted that the use of IVL with adjuvant intracoronary imaging has revolutionized the way of treating heavily calcified, non-dilatable coronary lesions and is likely to succeed the conventional ways of treating these complex lesions. We need further studies to gauge the long-term efficacy and safety of IVL against techniques currently available for calcium modification including conventional balloons, cutting or scoring balloons, rotational atherectomy and laser atherectomy.

Calcium Modification in Percutaneous Coronary Interventions

Moderate-severe calcification increases procedural complications and impairs long-term prognosis post-PCI. Intravascular imaging (particularly optical coherence tomography [OCT]) is useful in guiding the treatment of calcified lesions. Weighted sum of calcium length, arc, and thickness on OCT can predict adequate stent expansion, identifying when atherectomy is required. With intravascular imaging guidance, various techniques alone or in combination may be used in an algorithmic fashion to modify calcified lesions. Calcium fracture by balloon angioplasty, cutting/scoring balloons, intravascular lithotripsy (IVL), atherectomy devices, or Excimer laser improves stent expansion. Intravascular imaging is essential in the treatment of in-stent restenosis when luminal and/or abluminal peri-strut calcium is present.

Calcific Plaque Modification by Acoustic Shockwaves: Intravascular Lithotripsy in Cardiovascular Interventions

PURPOSE OF REVIEW

To provide a review of recent literature on the treatment of moderate-to-severe calcification in coronary and peripheral vasculature with intravascular lithotripsy (Shockwave Medical, Santa Clara, CA).

RECENT FINDINGS

Moderate-to-severe calcific plaques constitute a significant proportion of lesions treated with transcatheter interventions in the coronary and peripheral vascular beds and portend lower procedural success rates, increased periprocedural major adverse events, and unfavorable long-term clinical outcomes compared to non-calcific plaques. Intravascular lithotripsy (IVL) is a new technique that uses acoustic shock waves in a balloon-based system to induce fracture in the calcium deposits to facilitate luminal gain and stent expansion. IVL demonstrated high procedural success and low complication rates in the management of moderate-to-severe calcification in coronary and peripheral vascular beds and led to large luminal gain by modification of calcific plaque as assessed by optical coherence tomography. Further studies will determine the role of IVL in an integrated, protocolized approach to the treatment of severely calcified plaques in the coronary and peripheral vascular beds.

Propensity-score-matched comparison of safety, efficacy, and outcome of intravascular lithotripsy versus high-pressure PTCA in coronary calcified lesions

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Calcified coronary lesions are frequently in patients with coronary artery disease.

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Intravascular lithotripsy was shown to be safe and effective for treating calcified lesions in coronary artery disease.

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Data of intravascular lithotripsy in comparison to standard techniques are lacking.

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Intravascular lithotripsy showed higher rate of procedural success without differences in rate of MACE after 12 months in comparison to high- pressure NC-Balloon PTCA.

Background

Data regarding safety, efficacy, and outcome of intravascular lithotripsy (IVL) in comparison to standard techniques are lacking. This study sought to compare IVL with non-compliant high-pressure balloon percutaneous coronary angioplasty (PTCA).

Methods and results

We performed a retrospective propensity-score-matched study to compare procedural success in 57 consecutive patients who received IVL-guided PCI in calcified coronary lesions with 171 matched patients who were treated with high-pressure PTCA with a non-compliant (NC)-balloon. The mean minimal lumen diameter (MLD) for the IVL group was 1.08 ± 0.51 mm, and the median percent diameter stenosis on quantitative angiography was 70.2% (interquartile range, 60.2–78.6%). MLD in the high-pressure dilatation group was 0.97 ± 0.43 mm, and the median percent diameter stenosis was 71.5% (interquartile range, 58.5–77.0%). IVL-guided PCI reduced median stenosis to 17.5% (interquartile range, 9.3–19.8%) with an acute gain of 0.93 ± 0.7 mm. High-pressure dilatation resulted in a final median stenosis of 19.3% (interquartile range, 13.33–28.5%). Procedural success was significantly higher (82.5% vs. 61.4%; p: 0.0035) in the IVL group. MACE through 12 months occurred in 10.5% of cases in the IVL group and in 11.1% of the high-pressure group (p = 0.22). Angiographic complications (coronary dissection, slow or no reflow, new coronary thrombus formation, abrupt vessel closure) were very low (0.2% vs. 0.12%).

Conclusion

IVL resulted in a significantly higher rate of procedural success compared to high- pressure NC-balloon dilatation in patients with calcified coronary lesions. The rate of MACE through 12 months was similar to the standard therapy.

Percutaneous coronary intervention of complex calcific coronary lesions utilizing orbital atherectomy prior to transcatheter aortic valve replacement

BACKGROUND

Coronary artery disease (CAD), often with severe calcification, is present in up to 75% of patients with severe aortic stenosis (AS) referred for transcatheter aortic valve replacement (TAVR). Management of CAD in such patients is challenging. Orbital atherectomy (OA) is an effective treatment of severely calcified coronary lesions prior to stent implantation. However, there is limited data on the use of OA for percutaneous coronary intervention (PCI) to treat calcific CAD patients prior to TAVR (OA PCI + TAVR).

METHODS

Retrospective analysis of patients with moderate/severe calcific CAD and moderate/severe AS who underwent staged OA PCI + TAVR at one high-volume institution. Data were analyzed to assess the 1-year major adverse cardiac events after index OA PCI [MACE: death, target lesion revascularization (TLR), and myocardial infarction (MI)].

RESULTS

There were 18 patients (mean age of 82) treated with staged OA PCI + TAVR, and of those, 10 (56%) were male, 7 (39%) Caucasian, and 11 (61%) Hispanic/Latino. The average left ventricular ejection fraction was 49% and congestive heart failure was present in 12 patients (67%). There were no angiographic complications (0%), stent thrombosis (0%), or stroke events (0%). The 30-day and 1-year MACE rates were 5.6% (0% death, 0% TLR, 5.6% MI) and 17% (0% death, 11% TLR, and 17% MI [all non-Q-wave MI]), respectively.

CONCLUSIONS

In this single-center observational cohort series, patients with heavily calcified coronary lesions treated with OA prior to TAVR had low rates of MACE at 30 days and 1 year. The results demonstrate the feasibility and safety of OA for the treatment of complex calcific coronary lesions prior to TAVR. An up-to-date literature review of atherectomy before, during, or after TAVR in patients with concomitant severe AS and calcific CAD is also provided.

TABLE OF CONTENTS SUMMARY

There is limited data on the use of orbital atherectomy (OA) for percutaneous coronary intervention (PCI) to treat calcific coronary artery disease (CAD) patients prior to transcatheter aortic valve replacement (TAVR). Our primary aim was to evaluate the feasibility, safety, and 1-year outcome of OA PCI pre-TAVR in patients with complex CAD and severe aortic stenosis (AS). We also aimed to provide a brief up-to-date literature review of atherectomy before, during, or after TAVR in patients with concomitant severe AS and calcific CAD. This retrospective cohort study found that OA is feasible and safe for the treatment of severely calcified coronary lesions before TAVR, resulting in acceptable 30-day and 1-year outcomes.

Management of calcified coronary artery bifurcation lesions

Calcified coronary artery bifurcation lesions (CBL) remain a challenge for the interventional cardiologist. Evidence regarding treatment of CBL is minimal. Optimal plaque modification is the most important step prior to stent deployment. Provisional stenting is the preferred strategy for most bifurcation lesions. However, two-stent strategy should be considered for BL with compromised large SB (>2.5 mm) supplying a large territory, >70% SB stenosis and lesions more than 5 mm long. In this contemporary review article, we present a simplified approach to treating CBL and demonstrate the approach to specific case examples using our newly developed mobile application, BifurcAID.

Acupuncture as Adjuvant Therapy for Treating Stable Angina Pectoris with Moderate Coronary Artery Lesions and the Mechanism of Heart-Brain Interactions: A Randomized Controlled Trial Protocol

Background. Stable angina pectoris with moderate coronary artery lesions is a syndrome caused by coronary artery stenosis, which endangers the quality of life. Previous acupuncture studies have shown effectiveness as a complementary therapy for ischaemic heart disease. However, more clinical evidence is needed for verification, and the mechanism should be investigated, especially involving the functional interactions between the heart and brain. Therefore, we designed a clinical trial to provide more evidence for acupuncture efficacy and its mechanism in ischaemic heart disease. Methods/Design. A total of 80 participants will be randomized to the electroacupuncture group and sham-electroacupuncture group at a ratio of 1 : 1. This trial will be conducted over 8 weeks, including a 2-week screening, 2-week treatment, and 4-week follow-up. All participants will continue to receive similar basic disease treatment procedures before the trial (including lifestyle changes and treatment for standard supportive medications, hypertension, and hyperlipidaemia, such as aspirin, metoprolol succinate, atorvastatin, and sodium fosinopril). Additionally, 12 sessions of acupuncture will be administered during the treatment period. The main outcome is Seattle Angina Questionnaire scores. The other observation indices are the heart rate variability and self-rating anxiety scale and self-rating depression scale scores. To explore mechanisms based on the hypothesis of a correlation between heart and brain function, fMRI scans will be used to detect functional brain changes in 15 patients from each group at baseline and at the end of treatment. Finally, the efficacy of acupuncture will be evaluated, and the HRV and imaging data will be correlated with clinical data to investigate the possible relationships between the brain and heart activity. Discussion. This trial will provide evidence for acupuncture as adjuvant therapy for the treatment of stable angina pectoris with moderate coronary artery lesions. The results will shed light on potential mechanisms of heart-brain interactions underlying acupuncture as an adjuvant therapy for treating ischaemic heart disease. Trials registration: Clinical Trial, https://clinicaltrials.gov/ct2/show/ChiCTR1900024937. Registered 4 August 2019, http://www.chictr.org.cn/.

Intravascular shockwave lithotripsy as a treatment modality for symptomatic mesenteric ischemia

Chronic mesenteric ischemia has traditionally been treated with either open surgical revascularization or endovascular therapy. Endovascular surgery has typically been preferred due to the lower rates of peri-procedural and post-procedural morbidity, yet this comes at the expense of long-term durability. Intravascular shockwave lithotripsy is a technique utilized to modify intimal and medial calcified plaque in order to improve vessel expansion and patency. Intravascular lithotripsy has been investigated as both primary and adjunctive treatment for peripheral arterial and coronary arterial lesions, however, its use in the treatment of chronic mesenteric ischemia requires further investigation. We present a case of a 75-year-old woman with symptomatic mesenteric ischemia who underwent intravascular shockwave lithotripsy of a 99% stenosis superior mesenteric artery with an excellent outcome.

Outcomes with Orbital and Rotational Atherectomy for Inpatient Percutaneous Coronary Intervention

INTRODUCTION

Our objective was to describe the contemporary outcomes of orbital atherectomy (OA) vs. rotational atherectomy (RA) use for inpatient percutaneous coronary intervention (PCI) in the United States. Data on the use of OA vs. RA in contemporary inpatient PCI are limited.

METHODS

We queried the Nationwide Readmission Database (NRD) from January to November for the years 2016-2017 to identify hospitalizations of patients who underwent PCI with atherectomy. We conducted a multivariate regression analysis to identify variables associated with in-hospital mortality.

RESULTS

We included 77,040 records of patients who underwent inpatient PCI with atherectomy. Of those, 71,610 (93%) had RA, and 5430 (7%) had OA. There was no significant change in the trend of using OA or RA over 2016 and 2017. OA was less utilized in patients presenting with ST-segment elevation myocardial infarction (STEMI) (4.3% vs. 46.8%, p < 0.001). In our cohort, OA was associated with lower in-hospital mortality (3.1% vs. 5%, p < 0.001) and 30-day urgent readmission (< 0.01% vs. 0.2%, p = 0.009), but a higher risk of coronary perforation (1.7% vs. 0.6%, p < 0.001) and cardiac tamponade (1% vs. 0.3%, p < 0.001) and a higher cost of index hospitalization ($28,199 vs. $23,188, p < 0.001) compared with RA.

CONCLUSION

RA remains the predominant atherectomy modality for inpatient PCI in the United States (93%). There was no change in the trend of use for either modality over the years 2016 and 2017. OA was noted to have a lower incidence of in-hospital death, but a higher risk of coronary perforation and a higher cost of index hospitalization for the overall unmatched cohorts.

Therapeutic Approach to Calcified Coronary Lesions: Disruptive Technologies

PURPOSE OF REVIEW

Moderate or severe calcification is present in approximately one third of coronary lesions in patients with stable ischemic heart disease and acute coronary syndromes and portends unfavorable procedural results and long-term outcomes. In this review, we provide an overview on the state-of-the-art in evaluation and treatment of calcified coronary lesions.

RECENT FINDINGS

Intravascular imaging (intravascular ultrasound or optical coherence tomography) can guide percutaneous coronary intervention of severely calcified lesions. New technologies such as orbital atherectomy and intravascular lithotripsy have significantly expanded the range of available techniques to effectively modify coronary calcium and facilitate stent expansion. Calcium fracture improves lesion compliance and is essential to optimize stent implantation. Intravascular imaging allows for detailed assessment of patterns and severity of coronary calcium that are integrated into scoring systems to predict stent expansion, identifying which lesions require atherectomy for lesion modification. Guided by intravascular imaging, older technologies such as rotational atherectomy and excimer laser can be incorporated with newer technologies such as orbital atherectomy and intravascular lithotripsy into an algorithmic approach for the safe and effective treatment of patients with heavily calcified coronary lesions.

Calcific Plaque Modification by Acoustic Shock Waves: Intravascular Lithotripsy in Coronary Interventions

Constituting a significant proportion of lesions treated with transcatheter interventions in the coronary arteries, moderate-to-severe calcification portends lower procedural success rates, increased periprocedural major adverse events, and unfavorable long-term clinical outcomes compared with noncalcific plaques. Adapted from the lithotripsy technology for treatment of nephrolithiasis, intravascular lithotripsy is a new technique for treatment of severely calcific lesions that uses acoustic shock waves in a balloon-based system to induce fracture in the calcium deposits to facilitate luminal gain and stent expansion. Herein, we summarize the physics and characteristics of the currently available intravascular lithotripsy system (Shockwave Medical, Santa Clara, CA), the clinical data on intravascular lithotripsy use in the coronary arteries, and future directions for adoption of the technique in percutaneous coronary intervention.

Biologically-engineered mechanical model of a calcified artery

Vascular calcification is a commonly occurring pathological process and is recognized as an independent prognostic marker for cardiovascular morbidity and mortality. Recent progress in developing novel therapies to modify vascular calcification is critically hampered due to the lack of reliable in vitro experimental models that recapitulate the structural and mechanical attributes of calcified arteries. In this study, we show the ability to model the behavior of diffuse vascular calcification in vitro using biologically-engineered grafts approximating the composition, structure, and mechanical properties of arteries. Transmural calcification was achieved by exposing the acellular grafts of collagenous ECM to complete medium containing elevated Calcium (Ca) and Phosphate (P) concentrations. It was found that increasing the serum concentration from 2% to 10% increased the extent and degree of calcification based on histochemical, ultrastructural, chemical and thermal analyses. The presence of variably-sized spherical calcific deposits within the matrix further confirmed its morphological similarity to pathologic calcification. Mechanical testing demonstrated up to a 16-fold decrease in compliance due to the calcification, consistent with prior reports for calcified arteries. The model developed thus has potential to improve the design and development of interventional devices and therapies for the diagnosis and treatment of arterial calcification. STATEMENT OF SIGNIFICANCE: The presence of extensive vascular calcification makes angiographic/interventional procedures difficult due to reduced arterial compliance. Current attempts to develop safe and effective non-surgical adjunctive techniques to treat calcified arteries are largely limited by the lack of a physiologically relevant testing platform that mimics the structural and mechanical features of vascular calcification. Herein, we developed an off-the-shelf calcified artery model, with the goal to accelerate the pre-clinical development of novel therapies for the management of arterial calcification. To the extent of our knowledge, this is the first report of an in vitro tissue-engineered model of diffuse arterial calcification.

How Should We Treat Heavily Calcified Coronary Artery Disease in Contemporary Practice? From Atherectomy to Intravascular Lithotripsy

Heavily calcified and densely fibrotic coronary lesions continue to represent a challenge for percutaneous coronary intervention (PCI), as they are difficult to dilate, and it is difficult to deliver and implant drug-eluting stents (DES) properly. Poor stent deployment is associated with high rates of periprocedural complications and suboptimal long-term clinical outcomes. Thanks to the introduction of several adjunctive PCI tools, like cutting and scoring balloons, atherectomy devices, and to the novel intravascular lithotripsy technology, the treatment of such lesions has become increasingly feasible, predictable and safe. A step-wise progression of strategies is described for coronary plaque modification, from well-recognised techniques to techniques that should only be considered when standard manoeuvres have proven unsuccessful. We highlight these techniques in the setting of clinical examples how best to apply them through better patient and lesion selection, with the main objective of optimising DES delivery and implantation, and subsequent improved outcomes.

Computational Fluid Dynamics Modeling of the Burr Orbital Motion in Rotational Atherectomy with Particle Image Velocimetry Validation

Rotational atherectomy (RA) uses a high-speed rotating burr introduced via a catheter through the artery to remove hardened atherosclerotic plaque. Current clinical RA technique lacks consensus on burr size and rotational speed. The rotating burr orbits inside the artery due to the fluid force of the blood. Different from a common RA technique of upsizing burrs for larger luminal gain, a small burr can orbit to treat a large lumen. A 3D computational fluid dynamics (CFD) model was developed to simulate the burr motion and study the fluid flow and force in RA. A particle image velocimetry experiment was conducted to measure and validate the flow field including the radial and axial velocities and a pair of counter-rotating vortices near the burr equator in CFD. The hydraulic force on the burr and the contact force between the burr and the arterial wall were estimated by CFD. The contact force can be reduced by using smaller burr and lower rotational speed. Utilizing the small burr orbital motion has the potential to be an improved RA technique.

Zero-contrast percutaneous coronary intervention on calcified lesions facilitated by rotational atherectomy

Percutaneous coronary intervention (PCI) in patients with advanced chronic kidney disease (CKD) is challenging due to frequent presence of complex calcified lesions and the very high risk of contrast-induced nephropathy (CIN). We report a strategy of "zero contrast" PCI, guided by intravascular imaging and physiology, performed in three patients with advanced CKD in whom severe calcification necessitated rotational atherectomy (RA) to facilitate and optimize PCI. This approach resulted in safe and successful PCI while preserving renal function. © 2017 Wiley Periodicals, Inc.

Coronary artery calcification detection with invasive coronary angiography in comparison with unenhanced computed tomography

OBJECTIVE

The presence of extensive coronary artery calcifications (CAC) influences treatment decisions, particularly for revascularization. However, important CAC might be missed with invasive coronary angiography (ICA). Our aim was to determine the accuracy of ICA in the identification of CAC using computed tomography (CT) as reference standard.

PATIENTS AND METHODS

Overall, 349 consecutive patients who underwent both CT-based CAC-scoring and invasive coronary angiography within 60 days were retrospectively included. Two experienced operators classified CAC on ICA, without knowledge of CT-based CAC scoring, for each of the four main vessels as (0) absent, (1) mild, (2) moderate, or (3) dense calcifications. These scores were correlated with the CT-based Agatston CAC-scores, the noninvasive reference standard. The sensitivity, specificity, and accuracy of identified CAC using ICA were derived. Calcifications identified as moderate or dense on ICA or with a vessel-based Agatston score of more than 100 were considered important.

RESULTS

CT classified 671 (48%) of the 1396 vessels as having moderately or densely calcified vessels (Agatston score >100), whereas this was 137 (9.8%) using ICA (P<0.001). A significant correlation was found between the CT-based and ICA-based CAC-scores for all vessels (P<0.001). The sensitivity in detecting any CAC by means of ICA was 43% with a specificity of 92% and an accuracy of 55%. The sensitivity of important CAC identification by ICA was 19%, the specificity 99%, and the accuracy 61%.

CONCLUSION

The accuracy of ICA for the identification of calcifications is very low as only 19% of the relevant calcifications was identified. Preprocedural assessment of CAC with CT could be considered to improve the treatment approach.