Although the widespread adoption of timely invasive reperfusion strategies over the last two decades has significantly improved the prognosis of patients with ST-segment elevation myocardial infarction (STEMI), up to half of patients after angiographically successful primary percutaneous coronary intervention (PCI) still have signs of inadequate reperfusion at the level of coronary microcirculation. This phenomenon, termed coronary microvascular dysfunction (CMD), has been associated with impaired prognosis. The aim of the present review is to describe the collected evidence on the occurrence of CMD following primary PCI, means of assessment and its association with the infarct size and clinical outcomes. Therefore, the practical role of invasive assessment of CMD in the catheterization laboratory, at the end of primary PCI, is emphasized, with an overview of available technologies including thermodilution- and Doppler-based methods, as well as recently developing functional coronary angiography. In this regard, we review the conceptual background and the prognostic value of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), hyperemic microvascular resistance (HMR), pressure at zero flow (PzF) and angiography-derived IMR. Finally, the so-far investigated therapeutic strategies targeting coronary microcirculation after STEMI are revisited.

Introduction: Excessive stent strut protrusion in the distal left main (LM) from either the left anterior descending (LAD) or circumflex (Cx) artery following inadequate ostial stenting may complicate any later procedure involving the left coronary artery. In such case scenarios, intravascular ultrasound (IVUS) guidance provides accurate assessment of the ostial stent position and may facilitate subsequent management strategies and treatment. Case summary: We present a complex percutaneous coronary intervention (PCI) of LM bifurcation in a 49-year-old man following inadequate ostial Cx stenting that resulted in excessive stent protrusion in the distal LM segment, accompanied by a subsequent short 80–90% ostial LAD stenosis. Initially, IVUS was performed to confirm “floating struts” from a previous Cx ostial stenting and to ensure complete intraluminal placement of the wire within the stent leading to the Cx, precluding any side passage through the stent struts. Then, a second wire was inserted into the LAD through the most distal stent strut under live IVUS guidance. Further PCI was completed according to the principles of the double kissing mini-culotte technique. Final IVUS runs confirmed correct stent apposition and expansion in the LM, LAD and Cx segments. Conclusions: In cases involving the treatment of “free-floating” struts in the distal LM artery, intravascular imaging is essential to ensure optimal PCI outcomes.

Background: Coronary microvascular dysfunction is associated with adverse prognosis after ST-segment elevation myocardial infarction (STEMI). We aimed to compare the invasive, Doppler wire-based coronary flow reserve (CFR) with the non-invasive transthoracic Doppler echocardiography (TTDE)-derived CFR, and their ability to predict infarct size. Methods: We included 36 patients with invasive Doppler wire assessment on days 3–7 after STEMI treated with primary percutaneous coronary intervention (PCI), of which TTDE-derived CFR was measured in 47 vessels (29 patients) within 6 h of the invasive Doppler. Infarct size was assessed by cardiac magnetic resonance at a median of 8 months. Results: The correlation between invasive and non-invasive CFR was modest in the overall cohort (rho 0.400, p = 0.005). It improved when only measurements in the LAD artery were considered (rho 0.554, p = 0.002), with no significant correlation in the RCA artery (rho −0.190, p = 0.435). Both invasive (AUC 0.888) and non-invasive (AUC 0.868) CFR, measured in the recanalized culprit artery, showed a good ability to predict infarct sizes ≥18% of the left ventricular mass, with the optimal cut off values of 1.85 and 1.80, respectively. Conclusions: In patients with STEMI, TTDE- and Doppler wire-derived CFR exhibit significant correlation, when measured in the LAD artery, and both have a similarly strong association with the final infarct size.

Background Long-term stent healing after primary PCI of culprit unprotected left main (ULM) lesions is insufficiently explored. In this setting, large vessel size and bifurcation anatomy may limit angiographic stent optimisation and contribute to persistent strut malapposition and incomplete coverage. Objectives To identify OCT-derived geometric and healing parameters associated with long-term strut coverage and malapposition after angiography-guided primary PCI of culprit ULM lesions. Methods This single-center exploratory study included 30 patients with long-term OCT follow-up after angiography-guided primary PCI of culprit ULM lesions. OCT analysis was performed separately in three prespecified subsegments: the left main (LM), polygon of confluence (POC), and distal main branch (dMB). Five predefined strut-level healing outcomes were analysed: covered struts, malapposed struts, malapposed and uncovered struts, significantly malapposed struts (>400 μm), and significantly malapposed and uncovered struts. Associations between patient-level healing outcomes and OCT-derived measures of lumen geometry, stent dimensions, neointimal response, and an exploratory lumen–stent mismatch variable were assessed using univariable and multivariable linear regression. Results A total of 31,703 struts were analysed. Overall strut coverage was 90.7 ± 6.6%. Compared with the dMB, proximal ULM segments (LM and POC) showed lower strut coverage (82.8% and 84.2% vs. 93.9%, p< 0.001) and higher malapposition rates (17.4% and 14.2% vs. 0.4%, p< 0.001). In regression analysis, larger native lumen dimensions were associated with lower strut coverage and higher malapposition, whereas larger achieved stent area was associated with better strut healing. The exploratory lumen–stent mismatch variable was independently associated with all five healing outcomes in multivariable models (all p < 0.01). Conclusions After angiography-guided primary PCI of culprit unprotected left main lesions, long-term strut healing was significantly influenced by the mismatch between native reference lumen area and the achieved minimum stent area. Whether intravascular imaging–guided optimization of stent sizing and expansion in large-calibre left main anatomy improves strut healing requires further investigation.

Recanalization of a chronically occluded coronary artery (CTO) is one of the most complex percutaneous coronary interventions (PCI) in the field of interventional cardiology. In addition to all available recanalization techniques, most PCI CTO failures go to the inability of the wire to pass through the occlusion. We report a CTO case successfully treated using a dual-lumen catheter after single-lumen microcatheter (MC) failure (not enough support for the guidewire to cross the occlusion).

Introduction: Accurate assessment of left main (LM) coronary lumen dimensions is essential during percutaneous coronary intervention (PCI). Quantitative coronary analysis (QCA) is routinely used, yet its agreement with high-resolution intravascular imaging modalities such as optical coherence tomography (OCT) in the LM segment remains incompletely defined. Methods: Thirty patients who underwent LM PCI were evaluated using follow-up angiography and OCT. Eight matched lumen parameters were assessed using 2D QCA, 3D QCA, and OCT. Differences between modalities were analyzed using repeated-measures ANOVA for normally distributed variables and Friedman's test for minimal lumen area (MLA). The correlations were assessed descriptively, and agreement was evaluated using Bland-Altman analysis. Results: Significant modality-dependent differences were observed across most lumen parameters. QCA demonstrated strong associations with OCT for referenceand mean-based lumen metrics, whereas correlations were weaker for extreme (minimal and maximal) dimensions. Bland-Altman analysis revealed minor mean differences between QCA and OCT but wide limits of agreement, indicating substantial inter-individual variability despite consistency at the group level. Conclusion: QCA provides reasonably consistent estimates of reference and mean lumen dimensions in the LM segment but shows limited association with OCT for extreme measurements. Despite strong associations, individual variability remains considerable, supporting OCT as the preferred modality for precise lumen assessment, stent sizing, and procedural optimization in LM PCI.