Effects of Ranolazine and Ivabradine on Pulmonary Microhemodynamics in Experimental Model of Pulmonary Thromboembolism.

We studied changes of pulmonary microhemodynamics when modeling pulmonary artery thromboembolism on perfused isolated rabbit lungs after pretreatment with ranolazine and ivabradine. The increase in pulmonary artery pressure, pulmonary vascular resistance, and pre- and postcapillary resistance was less pronounced than in control animals, but was close to that in case of pulmonary thromboembolism after pretreatment with voltage-gated Na+ channel blockers lidocaine and ropivacaine. The increase of capillary filtration coefficient inversely correlated with values of capillary hydrostatic pressure. Thus, ranolazine and ivabradine exhibit the properties of voltage-gated Na+ channel blockers mainly in smooth muscles of pulmonary arterial vessels and promote the decrease in endothelial permeability.

Animal models of pulmonary arterial hypertension associated with atrial septal defect.

Pulmonary arterial hypertension (PAH) is a well-known complication of congenital heart disease (CHD). The lack of a satisfactory animal model for PAH associated with CHD (PAH-CHD) has limited progress in understanding the pathogenesis of PAH and the development of therapeutic agents. The development of a rat model for PAH associated with atrial septal defect (ASD) was achieved through atrial septal puncture and thermal ablation. Two and 4 weeks after modeling, hematoxylin and eosin staining showed that the vascular thickness, vascular thickness index, vascular area, and vascular area index in pulmonary arteries with an outer diameter of 50-300 µm in the PAH-ASD 2 and 4 weeks group were higher than those in the sham group (all P < 0.05). Alpha-smooth muscle actin (ɑ-SMA) staining showed that the medial thickness, medial thickness index, medial area, and medial area index in pulmonary arteries with an outer diameter of 50-300 µm at 2 and 4 weeks after modeling were significantly higher than those in the sham group (all P < 0.05). Additionally, mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) in the PAH-ASD 2 and 4 weeks groups were significantly higher than those in the sham group (both P < 0.05). Elastin van Gieson staining showed that the vascular obstruction score in the PAH-ASD 2 and 4 weeks group was significantly higher than that in the sham group (both P < 0.05). The PAH-ASD rats were successfully generated. These findings suggest that our model would be useful for further research into the pathogenesis, prevention, and treatment of PAH-ASD.

Smoking paradox in coronary function and structure of acute ST-segment elevation myocardial infarction patients treated with primary percutaneous coronary intervention.

BACKGROUND: The Smoking paradox has generated inconsistent findings concerning the clinical prognosis of acute ST-segment elevation myocardial infarction (STEMI) patients, while providing limited insights into coronary anatomy and function which are crucial prognostic factors. Therefore, this study aimed to further investigate the existence of smoking paradox in coronary anatomy and function. METHODS: This study divided STEMI patients into smokers and non-smokers. Quantitative coronary angiography, angiography­derived microcirculatory resistance (AMR) and quantitative flow ratio (QFR) were utilized to analyze coronary anatomy and function. These parameters were compared using multivariable analysis and propensity score matching. The clinical outcomes were evaluated using Kaplan-Meier curve and Cox regression. RESULTS: The study included 1258 patients, with 730 in non-smoker group and 528 in smoker group. Smokers were significantly younger, predominantly male, and had fewer comorbidities. Without adjusting for confounders, smokers exhibited larger lumen diameter [2.03(1.45-2.57) vs. 1.90(1.37-2.49), P = 0.033] and lower AMR [244(212-288) vs. 260(218-301), P = 0.006]. After matching and multivariate adjustment, smokers exhibited inversely smaller lumen diameter [1.97(1.38-2.50) vs. 2.15(1.63-2.60), P = 0.002] and higher incidence of coronary microvascular dysfunction [233(53.9%) vs. 190(43.6%), P = 0.002], but showed similar AMR and clinical outcomes compared to non-smokers. There was no difference in QFR between two groups. CONCLUSION: Smoking among STEMI patients undergoing pPCI was associated with smaller lumen diameter and higher occurrence of coronary microvascular dysfunction, although it had no further impact on clinical prognosis. The smoking paradox observed in coronary anatomy or function may be explained by younger age, gender, and lower prevalence of comorbidities.

Prognostic value of angiographic microvascular resistance in patients with ST-segment elevation myocardial infarction.

BACKGROUND: The Angiographic Microvascular Resistance (AMR), derived from a solitary angiographic view, has emerged as a viable substitute for the Index of Microcirculatory Resistance (IMR). However, the prognostic significance in ST-Segment Elevation Myocardial Infarction (STEMI) patients is yet to be established. This research endeavors to explore the prognostic capabilities of AMR in patients diagnosed with STEMI. METHODS: In this single-center, retrospective study, 232 patients diagnosed with STEMI who received primary Percutaneous Coronary Intervention (PCI) were recruited from January 1, 2018, to June 30, 2022. Utilizing the maximally selected log-rank statistics analysis, participants were divided into two cohorts according to an AMR threshold of 2.55 mmHg*s/cm. The endpoint evaluated was a composite of all-cause mortality or hospital readmission due to heart failure. RESULTS: At a median follow-up of 1.74 (1.07, 3.65) years, the composite endpoint event was observed in 28 patients within the higher AMR group and 8 patients within the lower AMR group. The higher AMR group showed a significantly higher risk for composite outcome compared to those within the low-AMR group (HRadj: 3.33; 95% CI 1.30‒8.52; p = 0.03). AMR ≥ 2.55 mmHg*s/cm was an independent predictor of the composite endpoint (HR = 2.33; 95% CI 1.04‒5.21; p = 0.04). Furthermore, a nomogram containing age, sex, left ventricle ejection fraction, post-PCI Quantitative Flow Ratio (QFR), and AMR was developed and indicated a poorer prognosis in the high-risk group for STEMI patients at 3 years. (HR=4.60; 95% CI 1.91‒11.07; p < 0.01). CONCLUSIONS: AMR measured after PCI can predict the risk of all-cause death or readmission for heart failure in patients with STEMI. AMR-involved nomograms improved predictive performance over variables alone.

Estimation of pulmonary vascular resistance for Glenn physiology.

Children with single ventricle heart disease typically require a series of three operations, (1) Norwood, (2) Glenn, and (3) Fontan, which ultimately results in complete separation of the pulmonary and systemic circuits to improve pulmonary/systemic circulation. In the last stage, the Fontan operation, the inferior vena cava (IVC) is connected to the pulmonary arteries (PAs), allowing the remainder of deoxygenated blood to passively flow to the pulmonary circuit. It is hypothesized that optimizing the Fontan anatomy would lead to decreased power loss and more balanced hepatic flow distribution. One approach to optimizing the geometry is to create a patient-specific digital twin to simulate various configurations of the Fontan conduit, which requires a computational model of the proximal PA anatomy and resistance, as well as the distal Pulmonary Vascular Resistance (PVR), at the Glenn stage. To that end, an optimization pipeline was developed using 3D computational fluid dynamics (CFD) and 0D lumped parameter (LP) simulations to iteratively refine the PVR of each lung by minimizing the simulated flow and pressure error relative to patients' cardiac magnetic resonance (CMR) and catheterization (CATH) data. While the PVR can also be estimated directly by computing the ratio of pressure gradients and flow from CATH and CMR data, the computational approach can separately identify the different components of PVR along the Glenn pathway, allowing for a more detailed depiction of the Glenn vasculature. Results indicate good correlation between the optimized PVR of the CFD and LP models (n = 16), with an intraclass correlation coefficient (ICC) of 0.998 (p = 0.976) and 0.991 (p = 0.943) for the left and right lung, respectively. Furthermore, compared to CMR flow and CATH pressure data, the optimized PVR estimates result in mean outlet flow and pressure errors of less than 5%. The optimized PVR estimates also agree well with the computed PVR estimates from CATH pressure and CMR flow for both lungs, yielding a mean difference of less than 4%.

Impact of Norepinephrine and Dopamine Infusion on Renal Arterial Resistive Index during Pre-Emptive Living Donor Kidney Transplantation: Propensity Score Matching Analysis.

Background: Living donor kidney transplantation (LDKT) is a crucial treatment for end-stage renal disease, with pre-emptive LDKT (transplantation before dialysis initiation) offering significant benefits in graft function and patient survival. The selection of a vasopressor during LDKT, particularly between norepinephrine and dopamine, and its impact on renal arterial hemodynamics measured using the renal arterial resistive index (RARI) is poorly understood. Methods: This retrospective observational cohort study enrolled 347 eligible pre-emptive LDKT recipients from the Seoul St. Mary's Hospital between January 2019 and June 2023. Utilizing propensity score matching (PSM), the patients were categorized into dopamine and norepinephrine groups to compare the effects of these vasopressors on the intraoperative RARI, postoperative estimated glomerular filtration rate (eGFR), and hourly urine output. The RARI was measured via the Doppler ultrasonography of the renal hilum and parenchyma post-graft vascular and ureteral anastomoses. Results: The preoperative differences in the recipients' and donors' characteristics were mitigated following PSM. The dopamine group exhibited higher intraoperative RARI values at the renal hilum (0.77 ± 0.11 vs. 0.66 ± 0.13, p < 0.001) and parenchyma (0.71 ± 0.1 vs. 0.6 ± 0.1, p < 0.001) compared to those of the norepinephrine group. However, these differences were not statistically significant on postoperative day 7. The norepinephrine infusion adjusted for the propensity scores was associated with significantly lower odds of an RARI > 0.8 (hilum: OR = 0.214, 95% CI = 0.12-0.382, p < 0.001; parenchyma: OR = 0.1, 95% CI = 0.029-0.348, p < 0.001). The early postoperative outcomes showed a higher eGFR (day 1: 30.0 ± 13.3 vs. 25.1 ± 17.4 mL/min/1.73 m2, p = 0.004) and hourly urine output (day 1: 41.8 ± 16.9 vs. 36.5 ± 14.4 mL/kg/h, p = 0.002) in the norepinephrine group. Furthermore, the long-term outcomes were comparable between the groups. Conclusions: Norepinephrine infusion during pre-emptive LDKT is associated with more favorable intraoperative renal arterial hemodynamics, as evidenced by a lower RARI and improved early postoperative renal function compared to those of dopamine. These findings suggest a potential preferential role for norepinephrine in optimizing perioperative management and early graft functions in LDKT recipients. Given the retrospective nature of this study, further prospective studies are needed to confirm these observations. Additionally, the study limitations include the potential for unmeasured confounding factors and the inability to determine causality due to its observational design.

Renal arterial resistive index as a prognostic marker in lupus nephritis patients.

INTRODUCTION: Lupus nephritis (LN) is known to be one of the most serious complications of SLE and it is a major predictor of poor prognosis. Despite the improvement in understanding the pathophysiology of lupus nephritis and greater improvement in diagnostic approaches, lupus nephritis patients have poorer outcomes. OBJECTIVES: Study the relation between renal resistive index (RRI) and renal function and histopathological parameters in lupus nephritis (LN) patients. Also to investigate the usefulness of RRI in predicting response to treatment. PATIENTS AND METHODS: This study included 126 patients who were split into two groups (group 1: 101 LN patients and group 2: 25 SLE patients without renal affection); and 100 healthy controls (group 3). The RRI was measured for all participants through a colored Doppler ultrasound examination. LN patients underwent renal biopsy and received their therapy and were followed up for 6 months. RESULTS: The RRI was significantly greater in the LN group (mean±SD; 0.64±0.07) than in SLE patients without nephritis (0.5884±0.04) (P<0.0001). The RRI was greater in LN class IV (P<0.0001). RRI significantly correlated with the chronicity index (r=0.704, P<0.0001), activity index (r=0.310, P=0.002), and serum creatinine (r=0.607, P<0.0001) and negatively correlated with eGFR (r=-0.719, P<0.0001). Almost eighty-five percent (84.8%) of LN patients responded to induction therapy. RRI was significantly greater in the nonresponder group (mean±SD, 0.73±0.02) than that in the responder group (0.63±.07) (P<0.0001). All non-responders to induction therapy while only 29.8% of responders had an RRI of ˃0.7. RRI, according to regression analysis was a significant predictor of response to treatment in LN patients. CONCLUSION: RRI was significantly greater in the LN group and significantly correlated with kidney function and histopathological parameters. RRI can predict response to induction therapy in LN patients.

Contemporary survival outcomes of congenital systemic-to-pulmonary shunt in children with borderline pulmonary vascular resistant index compared to Eisenmenger syndrome.

Pulmonary arterial hypertension (PAH) associated with congenital heart disease (PAH-CHD) is a complication that occurs after unrepaired significant systemic-to-pulmonary shunt. Treatment options for PAH-CHD-predominantly left-to-right (L-R) shunt in children with borderline-high pulmonary vascular resistant index (PVRi) have been debated. We aimed to assess the treatment and survival of children with PAH-CHD-predominantly L-R shunt with borderline to high PVRi, using Eisenmenger syndrome (ES) for comparison. In 1995-2021, a total of 142 patients with ES and 192 children with PAH-CHD-predominantly L-R shunt were eligible for our analysis. The PVRi in ES patients was 26.7 ± 16.8 WU m2. Most patients (91%) received PAH-targeted therapy. Of the 192 children with PAH-CHD-predominantly L-R shunt, the baseline PVRi was 9.2 ± 5.8 WU m2. A total of 64 patients (33.3%) had borderline PVRi (4-8 WU m2) and 98 patients (51%) had high PVRi (> 8 WU m2). Most patients (88.5%) responded to acute pulmonary vasodilatory testing and underwent repair, with 158 undergoing defect closure and 12 having fenestrated closure. A treat-and-repair strategy was used in 33 children (17.1%). The 10- and 15-year survival rates for patients with ES were 79.3% and 72.4%, respectively, which was significantly inferior to children with borderline PVRi [97.3% and 87.8% (p = 0.02)]; and high PVRi [91.6% and 89.5% (p = 0.06)], respectively. The survival rate of children receiving treat-and-repair was slightly higher than that of ES (p = 0.16). The independent mortality risk in children with PAH-CHD-predominantly L-R shunt was persistent PAH following the defect correction (adjusted hazard ratio 5.8, 95% CI 1.7-19.9, p = 0.005).Trial registration: TCTR20200420004.

Microcirculatory dysfunction in hypertrophic cardiomyopathy with chest pain assessed by angiography-derived microcirculatory resistance.

Chest pain, a common initial symptom in hypertrophic cardiomyopathy (HCM) patients, is closely linked to myocardial ischemia, despite the absence of significant coronary artery stenosis. This study explored microvascular dysfunction in HCM patients by employing angiography-derived microcirculatory resistance (AMR) as a novel tool for comprehensive assessment. This retrospective analysis included HCM patients with chest pain as the primary symptom and control patients without cardiac hypertrophy during the same period. The AMR was computed through angiography, providing a wire-free and adenosine-free index for evaluating microcirculatory function. Propensity score matching ensured balanced demographics between groups. This study also investigated the correlation between the AMR and clinical outcomes by utilizing echocardiography and follow-up data. After matching, 76 HCM patients and 152 controls were analyzed. While there was no significant difference in the incidence of epicardial coronary stenosis, the AMR of three epicardial coronary arteries was markedly greater in HCM patients. The criterion of an AMR ≥ 250 mmHg*s/m was that 65.7% of HCM patients experienced coronary microvascular dysfunction (CMD). Independent risk factors for CMD included increased left ventricular (LV) wall thickness (OR = 1.209, 95% CI 1.013-1.443, p = 0.036). Furthermore, an AMR_LAD ≥ 250 mmHg*s/m had an increased cumulative risk of the endpoint (log-rank p = 0.023) and was an independent risk factor for the endpoint (HR = 11.64, 95% CI 1.13-120.03, p = 0.039), providing valuable prognostic insights.

Prognostic Implications of Resistive Reserve Ratio in Patients With Nonobstructive Coronary Artery Disease With Myocardial Bridging.

BACKGROUND: Myocardial bridging (MB) is accompanied by the dynamic extravascular compression of epicardial coronary arteries, leading to intracoronary hemodynamic disturbance with abnormal coronary flow profiles. We aimed to evaluate the prognostic implications of resistive reserve ratio (RRR), a composite measure of flow and pressure parameters that represents the vasodilatory capacity of the coronary arteries, in patients with angina with nonobstructive coronary artery disease (ANOCA) and MB, in comparison with coronary flow reserve (CFR). METHODS AND RESULTS: In this retrospective cohort study, we included patients with ANOCA who underwent coronary reactivity testing, where MB was identified by transient constriction in coronary artery segments between systole and diastole. Abnormal CFR and RRR were defined as <2.5 and <2.62, respectively. Major adverse cardiac events, including cardiovascular death, stroke, myocardial infarction, heart failure, and late revascularization, served as outcomes. Among 1251 patients with ANOCA, 191 (15.3%) had MB. The prevalence of abnormal CFR or RRR was not significantly different between patients with and without MB (P=0.144 and P=0.398, respectively). Over a median follow-up time of 6.9 years, abnormal RRR predicted major adverse cardiac events in patients with MB (hazard ratio [HR], 4.38 [95% CI, 1.71-11.21]; P=0.002) and without MB (HR, 1.91 [95% CI, 1.38-2.64]; P<0.001). Abnormal CFR predicted major adverse cardiac events in patients without MB (HR, 2.15 [95% CI, 1.54-3.00]; P<0.001), whereas it was not predictive of major adverse cardiac events in patients with MB (HR, 2.29 [95% CI, 0.93-5.65]; P=0.073). CONCLUSIONS: In patients with ANOCA and MB, impaired RRR was superior to impaired CFR in distinguishing patients at a higher risk of future adverse events, suggesting that RRR may serve as a risk stratification tool in patients with MB and ANOCA.

Prognostic Value of Coronary Microvascular Dysfunction Assessed by Coronary Angiography-Derived Index of Microcirculatory Resistance in Patients With ST-Segment Elevation Myocardial Infarction.

BACKGROUND: CaIMR is proposed as a novel angiographic index designed to assess microcirculation without the need for pressure wires or hyperemic agents. We aimed to investigate the impact of caIMR on predicting clinical outcomes in STEMI patients. METHODS: One hundred and forty patients with STEMI who received PCI in Putuo Hospital of Shanghai from October 2021 to September 2022 were categorized into CMD and non-CMD groups according to the caIMR value. The baseline information, patient-related examinations, and the occurrence of MACE at the 12-month follow-up were collected to investigate risk factors in patients with STEMI. RESULTS: We divided 140 patients with STEMI enrolled into two groups according to caIMR results, including 61 patients diagnosed with CMD and 79 patients diagnosed with non-CMD. A total of 21 MACE occurred during the 1 year of follow-up. Compared with non-CMD group, patients with CMD showed a significantly higher risk of MACE. A multivariate Cox regression model was conducted for the patients, and it was found thatcaIMR was a significant predictor of prognosis in STEMI patients (HR: 8.921). Patients with CMD were divided into culprit vascular CMD and non-culprit vascular CMD, and the result found that culprit vascular CMD was associated with the incidence of MACE (OR: 4.75) and heart failure (OR: 7.50). CONCLUSION: CaIMR is a strong predictor of clinical outcomes and can provide an objective risk stratification for patients with STEMI. There is a strong correlation among leukocyte index, the use of furosemide, Killips classification, and clinical outcomes.

Endothelial Function Correlates With Pulmonary Pressures in Subjects With Clinically Suspected Pulmonary Hypertension.

Impaired pulmonary circulation hemodynamics are characteristic of pulmonary hypertension (PH). We therefore sought to evaluate possible correlations between endothelial function noninvasively assessed by brachial artery flow-mediated dilation (FMD) and hemodynamic parameters at right-sided cardiac catheterization in patients with clinically suspected PH. Consecutive outpatients with suspected PH were enrolled in the study. In all patients, endothelial function was assessed by FMD and hemodynamic parameters (pulmonary artery pressure [PAP]); pulmonary vascular resistances [PVR]) were derived by right-sided cardiac catheterization. For this study, 95 consecutive patients with suspected PH were enrolled (mean age 63 ± 13 years, 58% male) and included in the analysis. FMD values were significantly correlated with systolic (s)PAP levels (r = -0.29, p = 0.016); correlation with PVR was of borderline significance (r = -0.21, p = 0.78). After multivariable regression analysis including age, gender, tricuspid annular plane systolic excursion and peak tricuspid regurgitation velocity (peak TRV), and FMD, the latter remained significantly correlated with systolic pulmonary artery pressure (sPAP) values (B = -47, p = 0.02). After classifying patients according to median levels of peak TRV and FMD into 3 groups (neither, either, or both impaired), progressively increased levels of sPAP, mean PAP, and PVR were found (p for trend <0.001 in all cases). FMD values were inversely related to sPAP levels in a small population of patients with clinically suspected PH. In combination with peak TRV levels, FMD values noninvasively assessed were predictive of increased sPAP, mean PAP, and PVR.

Angiography-versus wire-based microvascular resistance index to detect coronary microvascular obstruction associated with ST-segment elevation myocardial infarction.

BACKGROUND: Microvascular obstruction (MVO) measured by cardiac magnetic resonance (CMR) after ST-segment elevation myocardial infarction (STEMI) has important prognostic implications. While invasive index of microvascular resistance (IMR) have been shown to predict the occurrence and extent of MVO, the role of the angiography-based microvascular resistance (Angio-IMR) for this purpose remains unknown. The present study aims to perform a head-to-head comparison of wire-based and angiography-derived microcirculatory resistance (IMR and Angio-IMR, respectively) for the detection of MVO. METHODS: Patients with a first STEMI and multivessel disease underwent CMR for detection of MVO, and angio-IMR and IMR measurements during PPCI and at 30 day follow up, both in STEMI culprit and non-culprit vessels. RESULTS: 58 patients were included (mean age 60.7 ± 9.9 years, 82% male). At the time of PPCI, angio-IMR and IMR exhibited significant correlation (r = 0.70, P < 0.001), and agreement (coefficient of agreement 0.58). Both indices showed good predictive value of MVO [Angio IMR: AUC 0.79 (95% CI: 0.667-0.928); IMR: AUC 0.70 (95% CI: 0.539-0.853); p = 0.15]. Angio-IMR 40 U and IMR 34 U were identified as best cut-offs for prediction of MVO. In non-culprit vessels, angio-IMR and IMR also correlated well (rho = 0.59, p < 0.001), with overall lower mean values compared to culprit vessels (Angio-IMR: 36 vs. 23; IMR: 39 vs. 22, p < 0.001 for both comparisons). CONCLUSION: Angio-IMR constitutes a valid alternative to wire-based IMR in predicting MVO in STEMI. Angio-IMR and IMR show a good correlation in the acute and subacute STEMI phases, both in culprit and non-culprit vessels.

Continuous thermodilution and microvascular resistance reserve during the index procedure in acute coronary syndrome without obstructive coronary artery disease: A pilot study.

BACKGROUND: In 5%-25% of non-ST-elevation acute coronary syndrome (NSTE-ACS) patients, coronary angiography reveals no obstructive coronary arteries (MINOCA). Coronary microvascular disease (CMD) is a potential causal pathophysiological mechanism in these patients and can be diagnosed by continuous thermodilution assessment. Recently, the microvascular resistance reserve (MRR) has been introduced as a novel index to assess the vasodilatory capacity of the microcirculation. However, continuous thermodilution and MRR have never been investigated in the acute setting in MINOCA patients and invasive assessment of the microcirculation in these patients are currently lacking. AIMS: The objectives of the study were to investigate the incidence of CMD (MRR ≤ 2.7) in patients with MINOCA and to evaluate the feasibility and safety of continuous thermodilution-based assessment during index coronary angiography in the acute setting. METHODS: This study was a prospective, observational, pilot study investigating coronary physiology in the acute setting in MINOCA patients. Patients admitted with a diagnosis of NSTE-ACS were eligible for inclusion. RESULTS: In total, 19 MINOCA patients were included in this analysis; the mean age was 70 ± 9 years, and 79% were females. CMD was present in 6 patients (32%). Qrest was significantly higher in the MRR ≤ 2.7 group compared to the MRR > 2.7 group (0.076 [0.057-0.100] vs. 0.049 [0.044-0.071] L/min, p = 0.03). Rµ,rest was significantly lower in the MRR ≤ 2.7 group compared to the MRR > 2.7 group (1083 [710-1510] vs. 1563 [1298-1970] WU, p = 0.04). No periprocedural complications or hemodynamic instability have occurred during continuous thermodilution assessment during the index coronary angiography. CONCLUSION: In patients admitted for MINOCA undergoing immediate coronary angiography, continuous thermodilution assessment and MRR are feasible and safe in the acute setting, and evidence of functional CMD could be observed in one-third of the MINOCA patients.

The resistive and pulsatility indices of the dorsal metatarsal artery for the screening of peripheral lower artery disease in patients with and without diabetes.

BACKGROUND: In lower extremity peripheral artery disease (PAD), the ankle-brachial index (ABI) is an easily reproducible diagnostic tool for PAD, but it loses reliability when > 1.4 due to calcification of the vessel wall. Patients with diabetes are at higher risk for wall calcification. In order to overcome the limitation and reliability of ABI, particularly in patients with diabetes, we decided to assess resistive (RI) and pulsatility index (PI) by ultrasound doppler of the dorsal metatarsal artery (DMA). RESULTS: We therefore analyzed 51 legs (32 patients), evaluating the correlation between PI, RI, and ABI. Patients with diabetes were 21 (65.6 %), accounting for 33 legs (64.7 %). Out of 51 legs assessed, 37 (72.5 %) cases had compressible arteries, whereas in 14 legs (27.5 %) ABI was not calculable due to wall calcification. PAD was significantly associated with lower both RI and PI of the DMA (both p < 0.000). RI, but not PI, showed a significant correlation (r = 0.535) with ABI, when ABI was less than 1.4, but not when ABI > 1.4. When analyzed separately, patients with diabetes showed a similar figure in comparison with those without diabetes (r = 0.600), RI, but not PI, showed a significant correlation with ABI. CONCLUSION: Dorsal metatarsal artery resistive index (MARI) showed a significant inverse correlation with PAD, similarly to ABI, irrespective of the presence of diabetes. MARI seems to be an effective screening tool for PAD even in patients with wall calcification. Further studies are needed for confirming the results of the present pilot study.

Impact of hyperaemic stenosis resistance on long-term outcomes of stable angina in the ILIAS Registry.

BACKGROUND: The hyperaemic stenosis resistance (HSR) index was introduced to provide a more comprehensive indicator of the haemodynamic severity of a coronary lesion. HSR combines both the pressure drop across a lesion and the flow through it. As such, HSR overcomes the limitations of the more traditional fractional flow reserve (FFR) or coronary flow reserve (CFR) indices. AIMS: We aimed to identify the diagnostic and prognostic value of HSR and evaluate the clinical implications. METHODS: Patients with chronic coronary syndromes (CCS) and obstructive coronary artery disease were selected from the multicentre ILIAS Registry. For this study, only patients with combined Doppler flow and pressure measurements were included. RESULTS: A total of 853 patients with 1,107 vessels were included. HSR more accurately identified the presence of inducible ischaemia compared to FFR and CFR (area under the curve 0.71 vs 0.66 and 0.62, respectively; p<0.005 for both). An abnormal HSR measurement was an independent and important predictor of target vessel failure at 5-year follow-up (hazard ratio 3.80, 95% confidence interval: 2.12-6.73; p<0.005). In vessels deferred from revascularisation, HSR seems to identify more accurately those vessels that may benefit from revascularisation rather than FFR and/or CFR. CONCLUSIONS: The present study affirms the theoretical advantages of the HSR index for the detection of ischaemia-Âinducing coronary lesions in a large CCS population. (Inclusive Invasive Physiological Assessment in Angina Syndromes Registry [ILIAS Registry], ClinicalTrials.gov: NCT04485234).

Effects of age on microvascular function in patients with normal coronary arteries.

BACKGROUND: It has been suggested that coronary microvascular function decreases with age, irrespective of the presence of epicardial atherosclerosis. AIMS: Our aim is to quantitatively investigate the effects of age on microvascular function in patients with normal coronary arteries. METHODS: In 314 patients with angina with no obstructive coronary artery disease (ANOCA), microcirculatory function was tested using the continuous thermodilution method. In 305 patients, the association between age and both resting and hyperaemic myocardial blood flow (Q), microvascular resistance (Rµ), absolute coronary flow reserve (CFR) and microvascular resistance reserve (MRR) was assessed. In addition, patients were divided into 3 groups to test for differences based on age quartiles (≤52 years [24.9%], 53-64 years [49.2%], ≥65 years [25.9%]). RESULTS: The mean age was 59±9 years with a range from 22 to 79 years. The mean resting Q (Qrest) was not different in the 3 age groups (88±34 mL/min, 82±29 mL/min, and 86±38 mL/min, R2=0.001; p=0.62). A trend towards a decreasing mean hyperaemic Q (Qmax) was observed with increasing age (223±79 mL/min, 209±84 mL/min, 200±80 mL/min, R2=0.010; p=0.083). The mean resting Rµ (Rµ,rest) were 1,204±460 Wood units (WU), 1,260±411 WU, and 1,289±455 WU (p=0.23). The mean hyperaemic Rµ (Rµ,hyp) increased significantly with advancing age (429±149 WU, 464±164 WU, 503±162 WU, R2=0.026; p=0.005). Consequently, MRR decreased with age (3.2±1.2, 3.1±1.0, 2.9±0.9; p=0.038). This trend was present in both the patients with (n=121) and without (n=184) coronary microvascular dysfunction (CMD). CONCLUSIONS: There is an age-dependent physiological increase in minimal microvascular resistance and decrease in microvascular function, which is represented by a decreased MRR and is independent of atherosclerosis. The age-dependent decrease in MRR was present in both patients with and without CMD and was most evident in patients with smooth coronary arteries.

Insights into RC time curve fit analysis of pulmonary artery pressure decay.

The notion of a constant relationship between resistance and capacitance (RC time) in the pulmonary circulation has been challenged by more recent research. The RC time can be obtained using either a simplified empirical approach or a semilogarithmic equation. Although direct curve-fit analysis is a feasible and ostensibly reference approach for RC analysis, it remains largely unexplored. We aimed to study the relationship between various RC methods in different states of pulmonary hemodynamics. Methods In total, 182 patients underwent clinically indicated right heart catheterization. The pressure curves were exported and processed using the MATLAB software. We calculated the RC time using the empirical method (RCEST), semilogarithmic approach (RCSL), and direct measurement of curve fit (RCFIT). Results Among 182 patients, 137 had pulmonary hypertension due to left heart disease (PH-LHD), 35 had pulmonary arterial hypertension (PAH), and 10 demonstrated normal hemodynamics (non-PH). RCEST consistently overestimated the RCFIT and RCSL measurements by a mean of 75%. With all three methods, the RC values were longer in the PAH (RCFIT = 0.36 ± 0.14 s) than in the PH-LHD (0.27 ± 0.1 s) and non-PH (0.27 ± 0.09 s) groups (p < 0.001). Although the RCSL and RCFIT values were similar among the three subgroups, they exhibited broad limits of agreement. Finally, the RCEST demonstrated a strong discriminatory ability (AUC = 0.86, p < 0.001, CI = 0.79-0.93) in identifying PAH. Conclusion RC time in PAH patients was substantially prolonged compared to that in PH-LHD and non-PH patients. The use of the empirical formula yielded systematic RC overestimation. In contrast, the semilogarithmic analysis provided reliable RC estimates, particularly for group comparisons.