‘RotaShock’ – A Revolution in Calcium Modification: Long‑term Follow-up from a Single High-volume Centre

The presence of coronary calcification is consistently associated with an increased risk of stent under-expansion, which itself is associated with a higher risk of target lesion failure (TLF) and future target lesion revascularisation (TLR).^1–5 Rotational atherectomy (RA) has a relatively long history and is a well-established technique for dealing with coronary calcification during percutaneous coronary intervention (PCI).^6–9 RA works mainly by modifying superficial calcification to ultimately facilitate optimal stent expansion.^10–13

The development of intravascular lithotripsy (IVL) in the last 5 years has provided interventional cardiologists with a novel strategy for dealing with calcification. IVL as a balloon-delivered strategy has a shorter learning curve, with a good safety profile and clinical efficacy to deal with both superficial and deeper wall (medial) calcification.^13–18 The mechanism by which IVL results in calcium modification has important differences to RA. IVL utilises an acoustic wave that effects calcium through compression forces, leading to macroscopic and microscopic fractures that affect vessel wall compliance, leading to full expansion of balloons and stents.^12,13,19

Given their complementary mechanisms of action, there has been interest in whether the use of these devices in conjunction could potentially be synergistic and offer improved procedural results.^12,13,20 This strategy has been labelled both ‘rotatripsy’ and ‘rotashock’ in the literature. For the remainder of this manuscript, we will use the term ‘RotaShock’ (RSK) because we believe that this terminology characterises the synergy and the order of utilisation of these devices. This strategy has been shown to be efficacious in a number of case reports and case series.^21–25 Recently a multicentre study of 160 patients treated with RSK demonstrated that this is a safe and efficacious strategy for severe coronary calcification.²⁰ However, there are no data on the outcomes of patients treated with RSK beyond 30 days.^12,20,26

Therefore, the aim of the present analysis was to assess the procedural and long-term outcomes of RSK in the management of complex coronary calcification.

Method

Study Participants and Data Collection

This was a single-centre retrospective analysis of consecutive patients treated with an RSK strategy for coronary calcification during PCI from January 2019 until September 2022. The study received approval from the local audit/service evaluation group. Baseline demographics, comorbidity details and details of the PCI procedure were extracted from the online clinical record. Angiographic images were reviewed to evaluate the length of the lesion and presence of significant bifurcation. In addition, when intracoronary imaging (ICI) was used to guide the procedure, these images were reviewed to provide the following data: degree of calcification arc; presence of nodular calcification; the minimum lumen area (MLA) before and minimum stent area (MSA) after PCI. The online record was then evaluated for periprocedural complications, target vessel revascularisation (TVR) and mortality during the analysis.

Procedure

Patients were included in this cohort if the supervising interventional cardiologist decided that a strategy of RSK was the most appropriate mechanism for achieving an optimal PCI result. RA was used first to create a channel to deliver the IVL balloon. Burr size was at the discretion of the supervising interventional cardiologist. RA was performed in line with standard techniques and a standard speed of 160,000 rpm, with a floppy rotawire used in all cases. The decision to perform IVL after RA was indicated by either evidence of insufficient calcium modification on ICI or suboptimal expansion of 1:1 sized non-compliant balloons following RA. The size (aiming for a 1:1 balloon : artery diameter) and number of IVL balloons was decided by the supervising interventional cardiologist (IC). IVL was performed using the Shockwave C2 system (Shockwave Medical) as per the standard IVL technique using the C2 80 pulse balloon.²⁷

Statistical Analysis

Continuous variables are expressed as the median with interquartile range (IQR) and categorical variables as the number and percentage. The improvement in luminal area was evaluated using the Wilcoxon signed-rank test. Kaplan–Meier curves were generated to assess mortality during follow-up and also mortality or TVR. All analysis was performed using SPSS v29.0 (SPSS, IBM Corporation).

Results

A total of 36 patients were treated for calcific coronary artery disease with RSK between January 2019 and September 2022. In that same timeframe there were 203 cases of RA and 211 cases of IVL. An RSK strategy was therefore used in 9.2% of cases in which RA or IVL was used for calcium modification. The majority of patients were male (n=29; 80.6%) and the median age was 75 years (IQR 70–79 years). The other baseline demographics and comorbidity details are listed in Table 1.

The majority of cases involved treating the left anterior descending artery (63.4%) with one-third involving the left main coronary artery. Most cases involved ICI guidance (88.9%). Despite the complexity of these cases, the majority were able to be performed solely using radial access (80.6%). The median lesion length was 60 mm (IQR, 40–80 mm) and nine cases (25.0%) involved treatment of a bifurcation. The majority of cases required only a single burr and single IVL balloon (Table 2). The median largest IVL balloon was 3.5 mm (IQR 3.0–4.0 mm), and in the majority of cases a total of 80 pulses were used (Figure 1). There were 16 cases (44%) in which a cutting or scoring balloon was used in conjunction with RSK: these were all used after RA, while in seven cases (44%) they were used prior to IVL and in nine cases (56%) they were used after IVL. When ICI data were available to review, 65% had nodular calcification and 80% had at least one area with 360° circumferential calcification. The rest of the procedural characteristics are listed in Table 2.

The final Thrombolysis in Myocardial Infarction (TIMI) grade in all cases was 3. In 23 of 36 cases (63.9%) there was a final ICI run and these data were available for analysis. The median MSA was 7.7 mm² (IQR 6.2–10.0 mm²), with a significant improvement compared with the original MLA (3.2 mm²; IQR 2.8–3.9 mm²; p=0.005). There were two access site complications: one left common iliac dissection, which was managed conservatively, and one guidewire-induced subclavian dissection that required a stent. Five IVL balloons burst but none had any clinical sequelae. The median follow-up was 942 days (IQR 645–1,306 days). TVR occurred in two patients at 149 and 776 days, respectively. Both of these lesions had 360° calcification. One lesion had nodular calcification, involved a bifurcation and had a total visual estimated lesion length of 120 mm. In both cases of TVR the restenosis occurred in the previously stented portion, with one being focal and the other more diffuse. Five patients died during the follow-up period (Figure 2). The cause of death was unknown in three of these patients, cardiovascular in one and non-cardiovascular in the other. Supplementary Figure 1 shows the Kaplan–Meier curve for either TVR or death.

Discussion

This retrospective cohort analysis evaluated the combined use of RA and IVL in patients with severe angiographically defined calcific coronary artery disease, with ICI confirmation in 88.9% of cases. Our analysis demonstrates that the strategy of RSK for management of severe coronary artery calcification is both safe and efficacious. Furthermore, this analysis is the first to evaluate outcomes beyond 30 days and demonstrates good long-term outcomes despite the complex nature of this cohort.

The concept of using compeimentary modalities for treating severe coronary calcification has been suggested and investigated previously. An analysis was carried out, using the British Cardiovascular Intervention Society (BCIS) database, of patients treated with a combination of RA and laser, coined ‘RASER’.²⁸ Only the in-hospital outcome was recorded and there was no increased risk of major adverse cardiac or cerebrovascular events. However, there was a higher risk of arterial access site complications, slow flow and induction of cardiogenic shock.²⁸

The recently published PREPARE-CALC-COMBO study evaluated whether the combination of RA and cutting balloons (Rota-Cut) was more effective than RA or a balloon strategy alone.²⁹ In that study, the final MSA was higher in the rota-cut cohort compared with the RA- or balloon-only cohorts.²⁹ Interestingly, in their cohort of patients with complex calcific coronary disease, the frequency of target vessel failure was 8.1% and that of mortality was 4.5% at 9-month follow-up.²⁹ Our cohort is likely to have had a similar complexity to the PREPARE-CALC-COMBO cohort and at 9 months had comparable outcomes (TVR 2.8% and mortality 5.6%). The TVR rates in our cohort are encouraging and sit between the 1-year TVR frequencies seen in the Disrupt-CAD III and IV studies.^30,31 Similar to RSK, IVL has been used in conjunction with orbital atherectomy for the same reasons. There have been a number of case reports and a few small case series demonstrating that this strategy is safe and effective, but as yet, there are no longer-term data on the outcomes of these patients.^12,26,32

This cohort represents a typical elderly population with concurrent multimorbidity seen with severe calcified coronary lesions. Similarly, in a previous study of 160 patients, the mean age was 72.7 years, the majority of patients were male, and patients had multiple comorbidities.^20,23,26 In our cohort one-third of cases involved the left main coronary artery, which is around double the frequency seen in the analysis by Sardella et al. (16.9%).²⁰

RSK combination therapy meant that the rota burr size in 75% of cases was 1.5 mm or less, meaning that the majority of these cases can be performed with 6 Fr guide catheters and radial access. Similarly, Sardella et al. found that most of their cohort were treated with a single burr (73.1%) of 1.5 mm or less (83.3%), again highlighting the feasibility of using the radial access site for RSK.²⁰ Furthermore, in terms of RA alone, a radial access route has previously been shown to have a trend towards lower bleeding and access site complications.³³ In terms of IVL, the majority of patients in our cohort (83.3%) and in the Sardella et al. study (70.8%) had 80 or more pulses.²⁰ Interestingly, data from the France LILI registry suggest that delivering 80 pulses is associated with a lower risk of target vessel failure and hence, if this is proven, then 80 pulses would become the target for completion of lithotripsy.³⁴

In the theoretical concept of RSK, the RA first creates a channel to facilitate the delivery of the relatively bulky IVL balloon.³² RA also removes spiculated calcific nodules, which potentially reduces the risk of IVL balloon puncture and hence this is the favoured sequence of device therapy.^20–24,32 Finally, the use of IVL following first RA burr negates the need to upsize to a larger burr and is more likely to be able to modify deep wall calcium. The rate of ICI use was high in the present study (88.9%) compared with the largest published cohort of RSK by Sardella et al. (52.5%), and in our opinion ICI is essential to provide an accurate assessment of lesion morphology and to determine whether additional modification is necessary after RA.^8,19,20,23 ICI-derived algorithms to guide calcium modification could be helpful in determining whether to use IVL after RA. In particular, the depth of calcium seen on optical coherence tomography, which is already used in calcium modification algorithms, may be helpful in the decision to use an RSK strategy.³⁵ The decision to use IVL after RA should be made based on the degree of calcium modification seen on ICI and the expansion of a non-compliant balloon.

The reported rates of immediate complications in the published RSK series so far range from 0.0% (in a cohort of 14 RSK cases) to 3.3%.^12,20,23,26 In the present series there were two access site complications but no immediate complications as a direct result of RSK, supporting the concept that this strategy is safe for dealing with severe coronary calcification.

The medium-term follow-up data presented in this analysis provide reassurance that an RSK strategy can provide a durable result despite the complex calcific coronary disease in an elderly multimorbid population. The two cases of TVR in this analysis highlight previous observations that long lesions and calcified nodules are more likely to result in TVR. The only other study to date to provide outcomes outside of hospital found a 30-day mortality of 9.1%.¹² At 30 days in our study there were no cases of mortality, but it is difficult to draw comparisons because of the relatively small numbers of patients and also because of the patient characteristics: the patients treated with RSK are an elderly multimorbid cohort who would be expected to have significant mortality regardless of their treatment. The largest cohort to date from Sardella et al. does not have long-term follow-up as yet, but this is planned and would clearly be helpful to our understanding of this strategy. The low complication frequency and encouraging long-term outcomes in our cohort are likely to be due, in part, to the high use of ICI.

Our data are encouraging for the combined device usage of RSK for lesion modification of calcified coronary disease. Further data are eagerly awaited from currently recruiting studies on the use of multimodality calcium modification strategies, particularly the combination of atherectomy with IVL.³⁶ In our opinion, any further studies should have ICI as an essential element to guide the decision-making strategy.

Limitations

Although this study enables a better understanding of the merits of an RSK strategy given it is the largest RSK cohort in the literature with medium-term outcomes, there are some important potential caveats to consider when interpreting this study. First, this was a single-centre retrospective analysis and as such has all of the limitations associated with this type of cohort, particularly the potential lack of generalisability. Second, a substantial part of the data used in this analysis were obtained through the contemporaneous documentation as part of the BCIS database. While these data are nationally recorded and assumed to be accurate, there is no independent cross-referencing to ensure complete accuracy. Third, and most importantly, this is a small cohort, in which selection bias is potentially important and hence further larger randomised studies are required to better understand the merits of this strategy. In particular, medium-term and ideally long-term outcome data are required to further evaluate this strategy, which would be best delivered as part of a randomised study comparing an RSK strategy with either RA or IVL as a single calcium modification strategy. Fourth, due to the retrospective nature of this database we were unable to evaluate the frequency of periprocedural MI, which, given the complexity of these cases, could be significant. Fifth, the follow-up in this study was clinically driven, with no angiographic follow-up outside this. Sixth, it was not possible to ascertain the cause of death in three cases in the present cohort, which is important to consider when interpreting this analysis. And last, despite the high use of ICI (88.9%), the final MSA was available only in 63.9% of patients, mainly due to the loss of ICI imaging data. In addition to these limitations, it is important to acknowledge that an RSK strategy has significant upfront costs associated with it. Although in many cases this strategy may be required to obtain a satisfactory result, it is essential that any future randomised studies include a cost analysis. The increased upfront cost of combination therapy may be offset by reduced TVR, which would negate any additional upfront cost of this strategy, but again this remains to be demonstrated.

Conclusion

The combination of RA and IVL, RSK, is a safe and effective strategy for modification of severe coronary calcification. Long-term outcomes suggest that this synergistic lesion preparation leads to a durable result. Further registry and/or randomised data are now mandated to evaluate the relative merits of RSK compared with RA or IVL alone to determine whether this should become a more established technique.

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