BACKGROUND: Patients with ST-segment–elevation myocardial infarction but no coronary microvascular injury are at low risk of early cardiovascular complications (ECC). We aim to assess whether nonhyperemic angiography-derived index of microcirculatory resistance (NH-IMR _angio ) could be a user-friendly tool to identify patients at low risk of ECC, potentially candidates for expedited care pathway and early hospital discharge. METHODS: Retrospective analysis of 2 independent, international, prospective, observational cohorts included 568 patients with ST-segment–elevation myocardial infarction. NH-IMR _angio was calculated based on standard coronary angiographic views with 3-dimensional-modeling and computational analysis of the coronary flow. RESULTS: Overall, ECC (a composite of cardiovascular death, cardiogenic shock, acute heart failure, life-threatening arrhythmias, resuscitated cardiac arrest, left ventricular thrombus, post-ST-segment–elevation myocardial infarction mechanical complications, and rehospitalization for acute heart failure or acute myocardial infarction at 30 days follow-up), occurred in 54 (9.3%) patients. NH-IMR _angio was significantly correlated with pressure/thermodilution-based index of microcirculatory resistance (r=0.607; P <0.0001) and demonstrated good accuracy in predicting ECC (area under the curve, 0.766 [95% CI, 0.706–0.827]; P <0.0001). Importantly, ECC occurred more frequently in patients with NH-IMR _angio ≥40 units (18.1% versus 1.4%; P <0.0001). At multivariable analysis, NH-IMR _angio provided incremental prognostic value to conventional clinical, angiographic, and echocardiographic features (adjusted-odds ratio, 14.861 [95% CI, 5.177–42.661]; P <0.0001). NH-IMR _angio <40 units showed an excellent negative predictive value (98.6%) in ruling out ECC. Discharging patients with NH-IMR _angio <40 units at 48 hours after admission would reduce the total in-hospital stay by 943 days (median 2 [1–4] days per patient). CONCLUSIONS: NH-IMR _angio is a valuable risk-stratification tool in patients with ST-segment–elevation myocardial infarction. NH-IMR _angio guided strategies to early discharge may contribute to safely shorten hospital stay, optimizing resources utilization.

BACKGROUND: The anatomic and physiological changes associated with severe aortic stenosis may influence the functional evaluation of coronary stenoses. In this study, we aimed to assess changes in functional resting and hyperemic indices before and immediately after transcatheter aortic valve implantation (TAVI) and their relationship with microvascular resistance. METHODS: In this pooled analysis of 3 prospective observational studies, fractional flow reserve (FFR), resting full-cycle ratio (RFR), and resting distal coronary pressure to aortic pressure ratio (Pd/Pa) were measured in patients with severe aortic stenosis before and after TAVI in the left anterior descending artery. Coronary microcirculation was also assessed using thermodilution-based methods, with microvascular resistance reserve (cutoff ≤3) used to identify coronary microvascular dysfunction. RESULTS: A total of 126 patients were included. Baseline Pd/Pa, RFR, and FFR measurements were 0.93±0.04, 0.90±0.07, and 0.89±0.07, respectively. Immediately post-TAVI, a small but significant decrease was observed for both RFR and FFR (RFR, 0.88±0.08; FFR, 0.88±0.08; P <0.05 for all). Coronary flow reserve and microvascular resistance reserve also remained unchanged. Applying the established cutoff values, 16 (12.7%) vessels had a positive FFR, while a higher proportion of vessels were positive for Pd/Pa and RFR (35.7% and 43.7%, respectively; P <0.001). The concordance between pre- and post-TAVI FFR was higher (92.8%) compared with Pd/Pa (75.4%) and RFR (73.8%) ( P <0.001 for both). The rate of disagreement between resting and hyperemic indices remained unchanged, regardless of the presence of coronary microvascular dysfunction. CONCLUSIONS: TAVI is associated with a small but significant reduction in FFR and RFR immediately post-procedure. Overall, the agreement between pre- and post-TAVI values of FFR was higher compared with resting indices.

Objectives: This study aimed to evaluate the prognostic value of coronary microvascular dysfunction (CMD) at long term after transcatheter aortic valve implantation (TAVI) and to explore its relationship with extravalvular cardiac damage (EVCD). Moreover, we sought to test the correlation between angiography-derived index of microcirculatory resistance (IMR_angio) and invasive IMR in patients with aortic stenosis (AS).Methods: This was a retrospective analysis of the Verona Valvular Heart Disease Registry (Italy) including 250 patients (83 (80–86) years, 53% female) with severe AS who underwent TAVI between 2019 and 2021. IMR_angiowas calculated offline using a computational flow model applied to coronary angiography obtained during the TAVI workup. CMD was defined as IMR_angio≥30 units.The primary endpoint was the composite of cardiovascular death and rehospitalisation for heart failure (HF). Advanced EVCD was defined as pulmonary circulation impairment, severe tricuspid regurgitation or right ventricular dysfunction.The correlation between IMR and IMR_angiowas prospectively assessed in 31 patients undergoing TAVI.Results: The primary endpoint occurred in 28 (11.2%) patients at a median follow-up of 22 (IQR 12–30) months. Patients with CMD met the primary endpoint more frequently than those without CMD (22.9% vs 2.8%, p<0.0001). Patients with CMD were more frequently characterised by advanced EVCD (33 (31.4%) vs 27 (18.6%), p=0.024). CMD was an independent predictor of adverse outcomes (adjusted HR 6.672 (2.251 to 19.778), p=0.001) and provided incremental prognostic value compared with conventional clinical and imaging variables. IMR_angiodemonstrated fair correlation with IMR.Conclusions: CMD is an independent predictor of cardiovascular mortality and HF after TAVI.

Objectives We hypothesised that low flow low gradient aortic stenosis (LFLGAS) is associated with more severe coronary microvascular dysfunction (CMD) compared with normal-flow high-gradient aortic stenosis (NFHGAS) and that CMD is related to reduced cardiac performance. Methods Invasive CMD assessment was performed in 41 consecutive patients with isolated severe aortic stenosis with unobstructed coronary arteries undergoing transcatheter aortic valve implantation (TAVI). The index of microcirculatory resistance (IMR), resistive reserve ratio (RRR) and coronary flow reserve (CFR) were measured in the left anterior descending artery before and after TAVI. Speckle tracking echocardiography was performed to assess cardiac function at baseline and repeated at 6 months. Results IMR was significantly higher in patients with LFLGAS compared with patients with NFHGAS (24.1 (14.6 to 39.1) vs 12.8 (8.6 to 19.2), p=0.002), while RRR was significantly lower (1.4 (1.1 to 2.1) vs 2.6 (1.5 to 3.3), p=0.020). No significant differences were observed in CFR between the two groups. High IMR was associated with low stroke volume index, low cardiac output and reduced peak atrial longitudinal strain (PALS). TAVI determined no significant variation in microvascular function (IMR: 16.0 (10.4 to 26.1) vs 16.6 (10.2 to 25.6), p=0.403) and in PALS (15.9 (9.9 to 26.5) vs 20.1 (12.3 to 26.7), p=0.222). Conversely, left ventricular (LV) global longitudinal strain increased after TAVI (−13.2 (8.4 to 16.6) vs −15.1 (9.4 to 17.8), p=0.047). In LFLGAS, LV systolic function recovered after TAVI in patients with preserved microvascular function but not in patients with CMD. Conclusions CMD is more severe in patients with LFLGAS compared with NFHGAS and is associated with low-flow state, left atrial dysfunction and reduced cardiac performance.

Myocarditis is a dynamic disease, and myocardial oedema, injury, ventricular dysfunction, and fibrosis may evolve differently over time. Cardiovascular magnetic resonance (CMR) has become central to its non-invasive assessment, providing complementary information on myocardial tissue through T2-sensitive imaging, native T1, extracellular volume (ECV), and late gadolinium enhancement (LGE). The meaning of these findings, however, depends on when imaging is performed. Follow-up CMR may therefore provide a better understanding of myocardial recovery, helping to characterize resolving myocardial injury, persistent tissue abnormalities, and residual post-acute changes. Based on the temporal evolution of CMR findings, we propose four conceptual patterns of myocardial recovery: near-complete imaging recovery; resolving oedema/injury-pattern abnormalities; persistent oedema/injury-pattern abnormalities; post-acute injury with residual LGE and potential structural remodelling. These patterns are intended as a framework for interpreting serial CMR rather than as formally validated imaging phenotypes, and should be considered complementary to contemporary clinical disease-stage and mechanistic classifications. In selected patients, integration with echocardiography, molecular imaging, genetics, and endomyocardial biopsy may provide further insight into the underlying disease process. Whether this longitudinal approach can improve risk stratification and ultimately guide therapeutic decisions remains an important question for future studies.