Survival and Health Status Outcomes Following IVUS-Guided Stent Optimization

Percutaneous coronary intervention (PCI) outcomes are significantly enhanced by intravascular ultrasound (IVUS) guidance.^1,2 While contemporary guidelines grant IVUS a class I recommendation,^3,4 real-world validation of absolute stent optimization targets remains underreported. We systematically evaluated the prognostic value of a predefined poststenting minimal stent area (MSA) cutoff in a large-scale, all-comers Vietnamese registry, investigating its relationship with long-term survival and longitudinal patient-reported health status (Seattle Angina Questionnaire-7 [SAQ-7]).⁵

Methods

Approved by the Institutional Ethics Committee of the University of Medicine and Pharmacy at Ho Chi Minh City (no. 75/GCN-HĐĐĐ), this retrospective registry consecutively enrolled all eligible patients undergoing IVUS-guided PCI at the University Medical Center Ho Chi Minh City between February 2023 and October 2024. To prevent misclassification bias, the primary endpoint was 1-year all-cause mortality. The secondary endpoint was longitudinal SAQ-7 score trajectories (baseline and 1, 3, and 12 months).

Two independent interventional cardiologists analyzed all IVUS pullbacks. Literature-derived MSA cutoffs were evaluated as time-to-event predictors for 1-year mortality using iterative multivariable Cox regression. Unlike the 5.0 mm² threshold (P = 0.225), a 5.5 mm² cutoff maintained robust predictive value, becoming our definitive optimal expansion criterion. Survival was analyzed via multivariable Cox proportional hazards models (adjusted for age, sex, diabetes, clinical presentation, baseline proximal reference vessel diameter). SAQ-7 trajectories were evaluated using an adjusted linear mixed-effects model utilizing random intercepts per participant to account for repeated measures and incorporating a multiplicative group × time interaction term to assess differing response trajectories.

Continuous variables are presented as mean ± SD or median (Q1-Q3) and compared using Student’s t test or Mann-Whitney U test. Categorical variables are expressed as count and percentage and evaluated via chi-square or Fisher exact tests. Statistical significance was defined as a 2-tailed P < 0.05. All statistical analyses were performed using Stata 17.0 (StataCorp).

Results

The cohort (N = 2,218) was stratified into optimal (MSA ≥5.5 mm², n = 1,386) and suboptimal (MSA <5.5 mm², n = 832) expansion groups. The suboptimal group was older, having more diabetes/hypertension, inherently smaller vessels, and longer lesions (all P < 0.05).

At baseline, suboptimal patients reported a heavier symptom burden (SAQ-7: 59.8 ± 17.3 vs 61.5 ± 16.7; P = 0.021). Post-PCI, both groups demonstrated dramatic, sustained improvements. Adjusted linear mixed-effects model estimates revealed comparable SAQ-7 scores at 1 month, becoming virtually identical by 3 months (75.5 [95% CI: 74.1-76.9] vs 75.4 [95% CI: 74.5-76.2]). At 1 year, the MSA <5.5 mm² cohort exhibited a steeper trajectory of symptomatic relief (group × time interaction P = 0.014), indicating robust angina relief regardless of the anatomical constraints (Figure 1).

Figure 1.

The Clinical Paradox of Intravascular Ultrasound–Guided Percutaneous Coronary Intervention

This large-scale, real-world registry (N = 2,218) stratified patients based on a minimal stent area (MSA) cutoff of ≥5.5 mm². (A) Over a 12-month follow-up, both the optimal (MSA ≥5.5 mm²) and suboptimal (MSA <5.5 mm²) expansion cohorts achieved comparable and profound symptom relief, as measured by adjusted Seattle Angina Questionnaire-7 (SAQ-7) trajectories. (B) However, despite this universal angina relief, achieving an MSA ≥5.5 mm² was robustly and independently associated with lower 1-year all-cause mortality (adjusted HR: 0.46; 95% CI: 0.22-0.98; P = 0.046).

Despite uniform symptom relief, 35 all-cause deaths occurred at 1 year (MSA <5.5 mm²: 21; MSA ≥5.5 mm²: 14). Multivariable Cox regression identified MSA ≥5.5 mm² as robustly and independently associated with lower 1-year all-cause mortality (adjusted HR: 0.46; 95% CI: 0.22-0.98; P = 0.046). Age independently increased mortality risk; diabetes, acute presentation, and baseline vessel size did not. Subgroup analyses yielded consistent protective point estimates favoring optimal expansion (HR: ∼0.4-0.5) across major clinical and anatomical strata; however, absolute event numbers within these subgroups were small (eg, 22 in males, 13 in females).

Discussion

This real-world registry reveals a clinical paradox: while IVUS-guided PCI confers profound, universal angina relief (SAQ-7) irrespective of final stent dimensions, achieving an MSA ≥5.5 mm² is strongly associated with a significant reduction in 1-year all-cause mortality (adjusted HR: 0.46; 95% CI: 0.22-0.98). Our findings align with landmark clinical trials establishing the absolute MSA >5.5 mm² as a superior prognostic indicator.^6,7

However, forcefully pursuing an absolute 5.5 mm² target in small vessels inherently risks barotrauma and medial edge dissections. Therefore, safely actualizing this anatomical threshold requires meticulous prestenting lesion preparation utilizing advanced calcium-modifying technologies, not solely aggressive high-pressure postdilation.

Limitations include, first, the observational design precluding absolute causality. Second, the low overall event rate (35 deaths [1.6%]) limits statistical precision. Consequently, wide CIs in female patients (typically possessing smaller vessel)⁸ and those with chronic coronary syndromes necessitate cautious interpretation. Finally, 1-year follow-up cannot confirm the permanence of the symptomatic “catch-up” effect. Furthermore, this steeper trajectory may partially reflect a ceiling effect, given lower baseline scores and 12-month clustering near 100 in both cohorts. Future studies with 3- to 5-year follow-ups, integrating relative expansion indices alongside absolute targets, are required to safely refine optimization algorithms.

Funding Support and author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.