Exploring a Metal-free Approach: Clinical Outcomes and Insights into Drug-coated Balloon Angioplasty in Sri Lanka

Outcomes of percutaneous coronary intervention (PCI) have improved significantly over the years with the use of new-generation drug-eluting stents (DES). Undoubtedly, DES were revolutionary. However, the risk of stent-related adverse events, such as in-stent restenosis (ISR) and acute stent thrombosis, remains. This adverse event risk continues to increase beyond the initial phase of PCI and does not plateau.¹ In a recent large-scale study, late stent-related events occurred between 1 and 5 years after PCI at a rate of ~2% per year for all stent types.² Several mechanisms have been postulated to explain the increased risk of ISR and stent thrombosis, including stent under-expansion, stent malposition, uncovered struts, hypersensitivity reactions, stent fracture and neo-atherosclerosis.³ These inherent limitations posed by foreign implants become particularly pronounced, especially in cases of complex PCI, such as those involving bifurcations. Newer evidence shows that permanent metallic residues following PCI can cause local arterial wall inflammation, endothelial dysfunction and disruption of vasomotion.⁴

Drug-coated balloons (DCBs) are a new way of treating coronary lesions that involve the concept of ‘leave nothing behind’. They are a promising alternative to treat de novo coronary artery disease (CAD) in small vessels and ISR. Furthermore, they may be the ideal solution for bifurcations and diffuse disease.

In the BASKET-SMALL 2 trial, DCBs were shown to be non-inferior to DES with regard to major adverse cardiac events (MACE) at 3 years in small native coronary arteries, with similar event rates in both groups.⁵ Although the rate of all-cause death was similar between the DCB and DES groups in that landmark trial, probable or definite stent thrombosis and major bleeding were numerically lower in the DCB population.⁵

In DCB angioplasty, the target vessel is not caged, which preserves the native configuration and causes a late luminal gain, which does not occur with DES. A recent South Korean meta-analysis demonstrated the benefits of DCB angioplasty when used as a standalone treatment or in combination with DES, with a significantly improved MACE rate and reduced stent burden compared with the DES-only strategy, in a complex multi-vessel setting.⁶

Although the concept of ‘metal-less PCI’ has become popular in recent times, several doubts do arise in the clinician’s mind prior to using DCB, especially with regard to proximal and larger vessel angioplasty and the need for bail-out stenting in the case of flow-limiting dissection or acute recoil. However, coronary dissections occurring immediately after DCB are more likely to be type A or type B, which are well-tolerated, supporting the conservative approach for non-flow-limiting dissections according to expert consensus.⁷ In an observational retrospective study, the use of DCB in large coronary vessels with long lesions was shown to be feasible and appeared to be safe, with only 6% requiring bail-out PCI with DES.⁸

Although DCB angioplasty has been studied extensively in many countries, there is currently no literature available with regard to the Sri Lankan population. The aim of this study was therefore to assess the behaviour of DCB in Sri Lankan patients with CAD.

Methods

This retrospective study included symptomatic patients (n=73) with angina, aged >18 years, who had undergone DCB angioplasty at Sri Jayewardenepura General Hospital between 2022 and 2024, at least 6 months prior to data collection. Both de novo lesions and ISR, treated with drug-eluting balloon (DEB), were considered. DCB incidents that required additional interventions such as bail-out stenting were excluded. Ethics approval was obtained from the Ethics Review Committee of Sri Jayewardenepura General Hospital prior to the commencement of the study.

Patient demographics, baseline characteristics, risk factors, lesion characteristics, procedure details and immediate outcomes were recorded retrospectively. Follow-up data collected in the clinic included all-cause mortality, chest pain, shortness of breath, readmission, recurrent MI, stroke, restenosis, and target lesion revascularisation, with a follow-up duration ranging from 6 months to a maximum of 2.8 years.

All analyses were performed using IBM SPSS version 27.0 (IBM Corporation). Quantitative data are presented as either a percentage or as median (IQR). The procedure success rate, that is, the percentage of times that the DCB procedure was completed successfully and achieved the intended outcome without major complications, was analysed using Kaplan–Meier curve. Long-term outcomes were evaluated using the MACE rate (i.e. cardiovascular death, non-fatal MI, non-fatal stroke and unstable angina requiring hospitalisation). All statistical tests were performed at a 95% confidence interval, and p<0.05 was considered as statistically significant.

Results

The median age of the study cohort was 58 years (IQR: 53.5–65.0 years), with 84.9% men and 15.1% women. Cardiovascular risk factors, including diabetes (53.4%), hypertension (49.3%) and dyslipidaemia (53.4%), were common. A total of 9.6% of patients were current smokers. Approximately one-quarter (24.7%) of the individuals had a history of smoking, and 21.9% of the patients used alcohol. There was no history of previous stenting for the majority (74%) of the patients. The remainder of the patients had previously been treated with one, two or three stents, with prevalence of 15.2%, 4.1% and 5.5%, respectively (Table 1 ).

Clinical presentation with ST-elevation MI (STEMI) was seen in 8.2% (n=6), non-STEMI in 50.7% (n=37), stable angina in 11.0% (n=8), unstable angina in 21.9% (n=16) and treadmill test positivity in 8.2% (n=6). According to angiogram findings, the majority (61.6%, n=45) had single-vessel disease, 30.2% (n=22) had double-vessel disease and 8.2% (n=6) had triple-vessel disease.

The left circumflex artery was the most commonly treated vessel (43.8%, n=32) using DCB angioplasty. A total of 35.6% of patients (n=26) had lesions in the left anterior descending artery, while 30.2% (n=22) had right coronary artery lesions. The right radial approach was used in almost all cases (93.2%), whereas the right femoral approach was used in 5.5% and the left femoral approach was used in one case (1.4%).

Of the lesions treated with DCB angioplasty, 97.26% (n=71) were de novo, whereas only 2.74% (n=2) were ISR. In four cases (5.48%), DCB had been used to treat chronic total occlusion (CTO). Treated lesions were mostly located distally (58.9%) in the respective vessel. Some lesions (30.2%) were located proximally, while the remainder (11.0%) were mid-vessel lesions. The median length and size of the DCB were 25 mm (IQR: 20–35 mm) and 2.25 mm (IQR: 2.00–2.75 mm), respectively. Paclitaxel-coated balloon was used in most cases (97.26%, n=71), and sirolimus-coated balloon was used in two (2.74%).

Coronary artery dissection was reported in 19.2% (n=14) of cases, as a complication during DCB angioplasty. Type A, B and D dissections were reported in 8.2%, 9.6% and 1.4% of cases, respectively (Table 2 ). Type A and Type B (92.9%) were left untreated, while Type D dissection (7.1%) was managed with the implantation of a DES.

All of the patients were alive at follow-up, hence all-cause mortality was 0%. Shortness of breath and chest pain were still present in 13.7% (n=10) and 19.2% (n=14) of the patients, respectively. A total of 4.1% (n=3) of the patients had been readmitted due to unstable angina. Recurrent MI was reported in 4.1% (n=3) of the patients, while 2.7% (n=2) of the patients had restenosis and underwent target lesion revascularisation (Figure 1 ). Hence, the incidence of MACE was 8.2% (n=6) in the overall study group, resulting in a procedure success rate of 91.8% (Figure 2 ).

All the patients were reported to have angina before undergoing DCB angioplasty. According to the Canadian Cardiovascular Society Angina Grading Scale, 46.6% were classified as having grade II angina, 37% as grade III and 16.4% as grade IV angina. Following DCB angioplasty, more than half of the patients (72.6%, n=53) were free from angina, while the remainder (27.4%) still had angina (Table 3 ). The difference in the distribution of angina grades before and after the procedure was statistically significant (p<0.001).

Discussion

DES implantation is still a major component of PCI for CAD. However, the patients, who may present with angina or acute coronary syndrome, are at risk of stent thrombosis and restenosis. DCB angioplasty, which does not require a vascular scaffold, such as a stent, presents a promising alternative to avoid such circumstances. DCB is currently used in the treatment of ISR, de novo distal and small vessel disease, and in cases of high bleeding risk. DCB is a relatively new concept in Sri Lanka and this is the first known study to assess the clinical outcomes in this population.

In this retrospective study, our objective was to shed light on the clinical outcomes and characteristics. Our study cohort had a median age of 58 years, and was predominantly male (84.9%), which is consistent with existing literature highlighting a higher prevalence of cardiovascular disease (CVD) among men. A significant population of our study cohort had common cardiovascular risk factors, such as diabetes (53.4%) and dyslipidaemia (53.4%). Although smoking is a major CVD risk factor, only 9.6% of our patients were current smokers, although approximately one-quarter had a previous history of smoking.

In this study population, the overwhelming majority had de novo lesions (97.26%), indicating that DCB was an effective treatment for this, rather than being used primarily for ISR. A total of 5.48% of the study population had CTO. A recent retrospective study on the clinical outcomes of DCB therapy for de novo CTOs showed acceptable MACE rates at 2-year follow-up.⁹ Another study showed that DCB without stenting in CTOs was feasible and well tolerated, provided that pre-dilatation was adequate.¹⁰

In general, the rate of coronary artery dissections is approximately 40%.¹¹ In the present study it was around 20%. The majority (92.9%) of the dissections that occurred during DCB angioplasty were type A and B, which were non-flow-limiting dissections. Hence, they were left untreated. Type D dissection was treated with a DES given that it causes flow limitations.

Kang et al. noted a MACE rate of 7.4%, which is largely similar to the 8.2% observed in the present study.⁷ The procedure success rate of DCB angioplasty is generally high, and often exceeds 90%.¹² In the present study, on Kaplan–Meier curve the procedure success rate for the DCB angioplasty was 91.8%. These findings are promising and contribute to the growing body of evidence supporting DCB as a viable treatment option for CAD.

A total of 72.6% of the present patients were angina free after the DCB angioplasty: a result that was statistically significant compared with baseline. In the remaining patients the cause of angina could be multifactorial, and includes the possibility of ischaemia with no obstructive coronary artery disease (INOCA) and underlying microcirculation dysfunction. Furthermore, adherence to medication could be a contributing factor.

Conclusion

Our study adds valuable data to the existing literature on DCB angioplasty and shows that it can be a safe and effective treatment option for patients with varied presentations of CAD. Further research is required for a better understanding of the long-term effects and to improve the therapeutic procedures. This is the first study on DCB angioplasty for the Sri Lankan population. As we improve cardiovascular care, it will be crucial to interact with patients, learn about their experiences, and address their concerns.