Prolonged high-pressure is required for optimal stent deployment as assessed by optical coherence tomography

A randomized controlled clinical trial of prolonged balloon inflation during stent deployment strategy in primary percutaneous coronary intervention for ST-segment elevation myocardial infarction: a pilot study

Background

Primary percutaneous coronary intervention (PPCI) is the standard procedure for reperfusion for ST-segment elevation myocardial infarction (STEMI), but the occurrence of the no-reflow phenomenon remains common and is associated with adverse outcomes.

Aims

This study aimed to evaluate whether prolonged balloon inflation in stent deployment would lessen the occurrence of the no-reflow phenomenon in PPCI compared with conventional rapid inflation/deflation strategy.

Methods

Patients were randomly assigned to either the prolonged balloon inflation in stent deployment group (PBSG) or conventional deployment strategy group (CDSG) in a 1:1 ratio. A subset of patients was included in the cardiac magnetic resonance (CMR) assessment.

Results

Thrombolysis in MI (TIMI) flow grade 3 was found in 96.7% and 63.3% of the patients of the PBSG and CDSG, respectively (P = 0.005). The results of the PBSG and CDSG are respectively shown as follows: 0% versus 30% no-reflow or slow flow (P = 0.002); 90% versus 66.7% ST-segment resolution ≥ 50% (P = 0.028); 35.6 ± 14.5 frames versus 49.18 ± 25.2 frames on corrected TIMI frame count (P = 0.014); and 60% versus 20% myocardial blush grade 3 (P = 0.001). At 1 month, the major cardiovascular adverse event (cardiovascular mortality) rate was 3.3% in both groups; at 1 year, the rate was 3.3% and 6.7% for the PBSG and CDSG, respectively (P = 1.00). In the CMR subset of cases, the presence of microvascular obstruction (MVO) was detected in 6.7% and 50% of the patients in the PBSG and CDSG, respectively (P = 0.023).

Conclusion

In our pilot trial, prolonged balloon inflation during stent deployment strategy in PPCI reduces the occurrence of the no-reflow phenomenon in patients with STEMI and improved the myocardial microcirculation perfusion (ClinicalTrials.gov number: NCT03199014; registered: 26/June/2017).

The Clinical and Angiographic Outcomes of Postdilation after Percutaneous Coronary Intervention in Patients with Acute Coronary Syndrome: A Systematic Review and Meta-Analysis

Objective

The effect of postdilation in patients with acute coronary syndrome is still controversial. This meta-analysis aims to analyze the clinical and angiographic outcomes of postdilation after percutaneous coronary intervention in patients with acute coronary syndrome.

Methods

PubMed, Embase, the Cochrane Library, Web of Science, CNKI, and Wangfang databases were searched from inception to August 30, 2020. Eligible studies from acute coronary syndrome patients treated with postdilation were included. The primary clinical outcome was major adverse cardiovascular events (MACE), the secondary clinical outcomes comprised all-cause death, stent thrombosis, myocardial infarction, and target vessel revascularization, and the angiographic outcomes were no reflow and slow reflow.

Results

11 studies met inclusion criteria. In clinical outcomes, our pooled analysis demonstrated that the postdilation had a tendency of decreasing MACE (OR = 0.67, 95% CI 0.45–1.00; P = 0.05) but significantly increased all-cause death (OR = 1.49, 95% CI 1.05–2.12; P = 0.03). No significant difference existed in stent thrombosis (OR = 0.71, 95% CI 0.40–1.26; P = 0.24), myocardial infarction (OR = 1.40, 95% CI 0.51–3.83; P = 0.51), and target vessel revascularization (OR = 0.61, 95% CI 0.21–1.80; P = 0.37) between postdilation and non-postdilation groups. In angiographic outcomes, there were no significant differences in no reflow (OR = 1.19, 95% CI 0.54–2.65; P = 0.66) and slow reflow (OR = 1.12, 95% CI 0.93–1.35; P = 0.24) between two groups.

Conclusions

The postdilation tends to reduce the risk of MACE but significantly increases all-cause death, without significantly affecting stent thrombosis, myocardial infarction, target vessel revascularization, and coronary TIMI flow grade. However, more randomized controlled trials are required for investigating the effect of postdilation for patients with acute coronary syndrome (registered by PROSPERO, CRD42020160748).

Numerical analysis of paclitaxel-eluting coronary stents: Mechanics and drug release properties

Since theoretical models provide data that cannot be otherwise gathered, numerical methods applied to medical devices analysis have emerged as fundamental tool in preclinical development. Large efforts were done to study mechanical and drug-eluting properties in stents but often the coating modelling is neglected. This work presents a finite element framework to calculate mechanical loads and drug distribution in three commercial drug-eluting stents (Palmaz-Schatz, Palmaz Genesis and Multi Link Vision), to check coatings strength and drug distribution maps in biological tissues. The promising copolymer poly(methylmethacrylate-co-n-butylmethacrylate), loaded with paclitaxel, is analyzed. Results demonstrated that the coating undergoes localized plastic phenomena, and calculated stresses are lower than the ultimate stress, ensuring coating integrity. Computed drug concentration depends on stent geometry and its values are in all cases lower than the toxicity level for this drug.

Prolonged Balloon Inflation to Effect Full Stent Expansion in Critical CAD During Left Ventricular Support

The extent to which a stent is expanded is a primary factor in determining both short- and long-term outcomes during percutaneous coronary intervention (PCI). This paper presents the first case of prolonged balloon inflation using the pressure optimization protocol allowing full stent expansion during PCI of critical coronary artery disease with severely reduced ejection fraction using the Impella. (Level of Difficulty: Intermediate.)

Impact of the Balloon Inflation Time and Pattern on the Coronary Stent Expansion

Objectives

To assess the expansion pattern of coronary stents by using different balloon inflation times and pressures.

Background

The selection of coronary stent size and its proper deployment is crucial in coronary artery interventions, having an impact on the success of the procedure and further therapy.

Methods

Ten pairs of different stents were deployed under nominal pressure using sequential (5, 5, 10, and 10 seconds of repeated inflations, thus 30 seconds of summarized time) and continuous (30 seconds) deployment pattern. After each given time-point, intraluminal stent measurements were performed by optical coherence tomography (OCT) and intravascular ultrasound (IVUS).

Results

Both in-stent diameters and cross-section areas (CSA) of paired stents measured by OCT at all sequential time-points were significantly smaller compared to given manufacturers charts' values (90% to 94% for diameters and 81% to 88% for CSA, p<0.05). Significant increase of in-stent diameter and CSA was observed across the step-by-step deployment pattern. In-stent lumen measurements were significantly larger when sequential deployment pattern was applied compared to continuous deployment. Additional measurements were also done for overlapping segments of stents, showing smaller in-stent measurements of the latter compared to nonoverlapping segments. Validation of OCT and IVUS measurements using a phantom metallic tube showed perfect reproducibility with OCT and overestimation with IVUS (8% for diameters and 16% for CSA).

Conclusions

Stent diameter after deployment is time-dependent and not only pressure-dependent. Different stent expansion behavior, depending on the applied deployment pattern (sequential and nonsequential), was observed.

Improved stent expansion with prolonged compared with short balloon inflation: A meta-analysis

BACKGROUND

Despite evidence from individual studies suggesting that prolonged inflation improves coronary stent expansion, relatively shorter inflation times are commonly employed in clinical practice.

METHODS

We performed an electronic search of PubMed, Web of Science, Cochrane, and CINAHL databases to retrieve outcome studies comparing prolonged versus short inflation times during stent deployment. Outcomes studied included minimal stent diameter (MSD) and minimal stent area (MSA). Standardized mean difference (SMD) was used to estimate the effect sizes for these continuous variables.

RESULTS

Seven studies with a total of 341 patients (415 lesions; mean age 67.6 years; 82% male) were included. Drug-eluting stents were used in 89 ± 15% of coronary lesions. Prolonged stent inflation was associated with increased minimal stent diameter (2.93 ± 0.34 mm vs. 2.72 ± 0.28 mm; SMD = 0.42; 95% CI 0.25-0.59; P < 0.001) and minimal stent area (5.99 ± 1.21 mm² vs. 5.17 ± 0.87 mm² ; SMD = 0.46; 95% CI 0.19-0.73; P = 0.001) compared with shorter duration stent inflation. This difference remained significant in sensitivity analyses that excluded studies with very prolonged inflation duration or multiple stent balloon inflations.

CONCLUSION

Despite differences in duration and methodology, prolonged stent inflation is associated with improved expansion compared with shorter duration. The effect of this optimization recommends randomized trials to determine whether long-term outcomes can be improved by this simple technical modification.

Optical coherence tomography-verified longer balloon inflation time may provide better stent apposition and optimal index parameters

BACKGROUND

Incomplete stent expansion and inadequate apposition predispose to stent thrombosis following percutaneous coronary intervention. Recent studies have shown that increasing the duration of balloon inflation during stent employment was beneficial. Thus, the balloon inflation time required for optimal stent expansion and apposition in patients receiving second-generation drug-eluting stents (DES) were determined using optical coherence tomography (OCT).

PATIENTS AND METHODS

Between April 2014 and March 2015, 38 patients (28 men, 10 women; mean age 60.5 ± 11.4 years) with stable angina pectoris due to single significant de novo coronary artery stenosis were prospectively enrolled. All patients were administered aspirin and clopidogrel and received weight-adjusted intravenous unfractionated heparin. Images of basal lesions were obtained using the C7XR LightLab Dragonfly OCT catheter.

RESULTS

Expansion and apposition parameters improved with increasing duration of balloon inflation (30 s or 60 s) with nominal pressure (12 atm). Mean lesion length was 19.8 ± 7.6 mm. Mean stent diameter and length were 2.8 ± 0.36 mm and 24.9 ± 7.6 mm, respectively.

CONCLUSION

With deployment of a stent at nominal pressure with conventional duration, inadequate stent expansion and malapposition frequently occurred as detected by OCT; however, a balloon inflation duration of 60 s markedly improved stent expansion and apposition parameters without significant complications.

Full stent expansion of chronic total occlusion lesions requires prolonged inflation

Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has been associated in some studies with higher target vessel revascularization (TVR) rates than non-CTO PCI. Optimal stent inflation time and its effect on TVR in CTO PCI is unknown. We investigated the time required for stent deployment using the previously described pressure optimized protocol (POP), which uses stent balloon pressure stability rather than an arbitrary inflation time as an end point for balloon deflation. We also compared TVR with CTO PCI vs non-CTO using the POP protocol in both groups.

METHODS

Patients with successful CTO PCI using POP between 2012 and 2015 were included. Patients having non-CTO PCI using POP and matched for stent diameter and length and temporal proximity constituted the control group to compare inflation time (n=83 each). TVR at 1year was compared between PCI during the time period using POP (CTO=83, non-CTO=263).

RESULTS

Stent inflation time to achieve optimal stent inflation using POP was longer in CTO vs non-CTO lesions (136±60 vs 108±51s, p=0.001). TVR at 365days was similar in CTO and non-CTO cohorts (2.4% vs 2.6%, p=0.9).

CONCLUSION

Stent expansion using POP in CTO lesions requires longer inflation duration but leads to similar TVR rates at 1year in CTO PCI compared with non-CTO PCI.

Classification of mechanisms of strut malapposition after angiographically optimized stent implantation: An optical coherence tomography study

AIMS

To elucidate causes and extent of strut malapposition in angiographically optimized stenting.

METHODS AND RESULTS

Using a new classification system for strut malapposition, the mechanisms of stent strut malapposition were classified as localized lumen enlargement, vessel asymmetry, stent undersizing, strut underexpansion and stent deployment issue. Stent implantations (n = 110) in 100 consecutive patients undergoing optical coherence tomography (OCT) after the operator considered the stent as optimally deployed angiographically were reviewed to determine if strut apposition was complete. 127,894 stent struts in 110 stents were analyzed. There were 6,644 struts malapposed (5.2% ±7.3%), with strut malapposition found in 82 of 110 stents (74.5%). Localized lumen enlargement was the most common cause of malapposition (74.4% of malapposition clusters). Stent undersizing was the second most common cause (46.3%) followed by strut under-expansion in 29.3%, stent deployment issue in 18.2%, and vessel asymmetry in 9.7%.

CONCLUSION

Malapposition of any degree is common after angiographic stent optimization, occurring in up to three-quarters of stents. The most frequent mechanism was localized lumen enlargement. The second most common cause of strut malapposition was stent undersizing, which was angiographically invisible. Whether performing OCT after angiographic optimization improves short- and long-term outcomes requires further study. © 2017 Wiley Periodicals, Inc.

Usefulness of Post-coronary Dilation to Prevent Recurrent Myocardial Infarction in Patients Treated With Percutaneous Coronary Intervention for Acute Coronary Syndrome (from the BASE ACS Trial)

Stent underexpansion is associated with worse outcome after stent implantation. Whether post-dilation (PD) improves outcome in patients with acute coronary syndrome (ACS) remains unclear. We performed post hoc analysis of outcome in patients from the BASE ACS (A prospective randomized comparison of titanium-nitride-oxide-coated bioactive stents with everolimus-eluting stents in acute coronary syndrome) trial who underwent PD versus those who did not. The BASE ACS trial randomized 827 patients (1:1) with ACS to receive either titanium-nitride-oxide-coated bioactive stents or everolimus-eluting stents. The primary end point was major adverse cardiac events (MACE): a composite of cardiac death, nonfatal myocardial infarction (MI), or ischemia-driven target lesion revascularization. Follow-up was planned at 12 months and yearly thereafter for up to 7 years. Of 827 patients enrolled in the BASE ACS trial, 357 (43.2%) underwent PD. Median follow-up duration was 5 years. Patients who underwent PD had less frequent nonfatal MI events at long-term follow-up, compared with those who did not (4.5% vs 8.5%, respectively, p = 0.02). The rates of MACE (15.7% vs 15.1%, respectively, p = 0.81), and the other endpoints, were not significantly different (p >0.5 for all). The results were consistent in propensity score-matched analysis (270 pairs). In patients treated with bioactive stents, those who underwent PD had a trend for a fewer nonfatal MI events (p = 0.076). Comparably, in patients treated with everolimus-eluting stents, MACE and all the individual end points were comparable (p >0.5 for all). In conclusion, patients treated with early percutaneous coronary intervention for ACS who underwent PD had less frequent nonfatal MI events at long-term follow-up, compared with those who did not; MACE rates were not significantly different.

Deploying bioresorbable vascular scaffolds--tardus, altius, amplius!!

Current generation bioresorbable vascular scaffolds (BVS) have thick struts and relatively low radial strength; meticulous deployment is required to prevent underexpansion while avoiding stent fracture. The current study suggests safety of very high-pressure (mean 28 atm) post-dilation of BVS with a noncompliant balloon. Duration of inflation and inflation pressure stabilization are important factors that influence the extent of optimal stent expansion and should be studied in future attempts to optimize BVS deployment.

The duration of balloon inflation affects the luminal diameter of coronary segments after bioresorbable vascular scaffolds deployment

BACKGROUND

Adequate expansion is critical to achieve optimal Bioresorbable Vascular Scaffolds (BVS) apposition to the vessel wall. However, compared to metallic stents, BVS present different mechanical properties. Hence, slow deployment and maintenance of balloon inflation for at least 30" is recommended for BVS implantation. However, since no evidences are available demonstrating the superiority of a longer balloon dilatation time, the implantation technique is highly variable among different centers.

METHODS

A total of 24 BVS-treated lesions were included in the present analysis. After BVS deployment at 12 atmosphere (ATM) the balloon was rapidly deflated and scaffold expansion was documented with an angiogram. The same balloon was then inflated again and kept at 12 ATM for 30". Finally, a further angiogram was obtained to evaluate BVS expansion. Quantitative coronary angiography (QCA) was performed at each step.

RESULTS

A significant increase of minimal luminal diameter (MLD)-to-reference scaffold diameter (RSD) ratio (MLD to RSD Ration, MR-Ratio) from 0.70 ± 0.10 after initial stent deployment to 0.79 ± 0.10 after the 30"-long balloon dilation was observed (p < 0.001). Of note, this result was consistent across all sub-segments, as well as across almost all lesion subgroups. A substantial reduction in the prevalence of residual stenosis from 29 % to 17 % was registered after the 30"-long dilation.

CONCLUSIONS

Our results strongly support the maintenance of balloon inflation for at least 30" during BVS deployment to achieve optimal scaffold expansion and minimize the occurrence of residual stenosis.