DCB vs. DES in Young STEMI Patients: The DCB-STEMI Trial

INTRODUCTION Patients with acute myocardial infarction (AMI) are among the highest-risk patients undergoing PCI and are mostly treated with drug-eluting stents (DES). Stenting reduces elastic recoil, restenosis, and flow-limiting dissections associated with balloon angioplasty. However, it increases the risk of in-stent restenosis (ISR), bleeding from prolonged dual antiplatelet therapy (DAPT), early and late stent thrombosis, and endothelial and vasomotor dysfunction.

In young patients (<50 years), lifetime management after stenting carries unique economic and social consequences. Stent implantation means a lifelong risk of ISR, stent thrombosis, and strict adherence to DAPT-a major compliance and financial issue in this age group.

These limitations have led to the development of drug-coated balloons (DCB), which deliver antiproliferative drugs into the vessel wall without leaving a permanent implant. This "leave nothing behind" strategy is particularly attractive in young patients and those with high bleeding risk. DCBs have shown promise in ISR, small vessel disease, and STEMI. Paclitaxel-coated balloons are most commonly used, delivering 2.0-3.5 µg/mm² of paclitaxel with cytotoxicity lasting at least 14 days. With a 30-second balloon inflation, about 16% of the drug is transferred to the vessel wall, ensuring homogenous delivery while avoiding permanent implants, stent thrombosis, ISR, and prolonged DAPT.

Several studies and meta-analyses have demonstrated comparable outcomes between DCBs and DES in AMI, including STEMI. In a large multicenter analysis of STEMI patients, DCBs were associated with similar mortality and target lesion revascularization compared to DES. Other feasibility studies confirmed no excess risk of abrupt closure, thrombosis, or target vessel failure when DCBs were used in primary PCI.

Cardiovascular disease, especially AMI, remains the leading global cause of death. South Asia bears a particularly high burden, with Pakistan at the top for premature MI. The National Institute of Cardiovascular Diseases (NICVD), Karachi, has become the world's largest primary PCI center, performing 17,761 primary PCIs in 2022. Notably, 45% were in young patients (<50 years) and 12% in very young (<40 years). This provides a unique opportunity to study DCB vs DES in a high-volume RCT focused on young STEMI patients.

________________________________________ STUDY DESIGN This is a randomized controlled trial comparing DCB vs DES in young (<50 years) STEMI patients undergoing primary PCI.

Hypothesis: DCB is non-inferior to DES in reducing Vessel Oriented Composite Endpoint (VOCE) at one year.

Primary Objective: Compare 1-year VOCE between DCB and DES in young STEMI patients.

Secondary Objectives: Compare vessel-oriented CV events, target vessel failure, vessel-related MI, stent thrombosis, bleeding, TIMI III flow, residual stenosis, abrupt closure, and bailout stenting.

________________________________________ METHODS

• Design: Single-center RCT at NICVD Karachi.
• Duration: 12 months.
• Randomization: Block randomization (1:1) using sealed envelopes.
• Sample Size: 496 patients (248 per arm). Based on non-inferiority design, assuming VOCE 8.5% with DES and 6.25% with DCB, non-inferiority margin 4.5%, 80% power, 5% dropout.

Inclusion Criteria:

• Age 18-50 years
• STEMI as first coronary artery disease (CAD) presentation
• Primary PCI within 8 hours of ischemia
• Low SYNTAX score
• Killip class I-II

Exclusion Criteria:

• ESRD
• Severe 3-vessel disease or high SYNTAX score
• Complex lesions >B or large thrombus despite preparation
• Refusal of consent
• Killip III/IV
• Major bleeding history

INTERVENTIONS

• DCB Arm: Paclitaxel-coated balloon (3.0 µg/mm²), inflated for 30 seconds after adequate lesion preparation. Successful result defined as TIMI III flow, ≤30% residual stenosis, and absence of major dissection. Bailout stenting permitted if needed, but patient analyzed in DCB arm (intention-to-treat).
• DES Arm: Standard second-generation drug eluting stent with routine lesion preparation.

IVUS Substudy:

100 patients in the DCB arm will undergo IVUS at baseline, post-procedure, and 6 months to assess vessel remodeling and late lumen loss.

DAPT Protocol:

Ticagrelor 90 mg BID for 1 month post-PCI, followed by DAPT up to 1 year.

________________________________________ DATA COLLECTION \& FOLLOW-UP

• Baseline demographics, risk factors, and angiographic data recorded.
• Clinical follow-up at 14 days, 30 days, 3 months, 6 months, and 12 months via visit/phone.
• Events tracked: death, MI, stent thrombosis, bleeding, stroke, repeat PCI, CABG, arrhythmias, and adverse drug reactions.
• Data captured on CRFs and stored securely.

ENDPOINTS

Primary Endpoint:

• 1-year VOCE (all-cause mortality, target vessel MI, TLR).

Secondary Endpoints:

• TIMI III flow rates
• Residual stenosis (>30% in DCB, >20% in DES)
• Bailout stenting
• Vessel-oriented events
• Bleeding

QUALITY CONTROL \& ETHICS

• Ethics approval obtained from NICVD.
• Written informed consent (English/Urdu).
• Independent DSMB to monitor safety and review pilot data weekly.
• Event Adjudication Committee to validate endpoints.
• Data stored per GCP for 10 years.
• Medtronic to provide financial support but with no role in design, conduct, or analysis.

PILOT PHASE An initial pilot of 50 patients will assess safety of the DCB-only strategy in STEMI. Focus will be on lesion preparation, abrupt closure, and bailout stenting. If safe, full enrollment will proceed.

________________________________________ STATISTICAL ANALYSIS

• Population: Intention-to-treat for efficacy; modified ITT for safety.
• Categorical Variables: Chi-square or Fisher's exact.
• Continuous Variables: T-test or Wilcoxon rank-sum.
• Time-to-Event: Kaplan-Meier with log-rank test; Cox regression for hazard ratios and subgroup analysis.
• Significance: p<0.05.
• Subgroups: Age (<40 vs ≥40), sex, smoking, diabetes, renal function, weight.

SIGNIFICANCE This trial addresses a critical gap in managing young STEMI patients in South Asia, a population with extremely high disease burden and unique socioeconomic challenges. If non-inferiority of DCB is confirmed, it could reshape PCI practice by reducing long-term stent-related complications, improving compliance, and lowering financial strain in younger patients.