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Introduction The bolus thermodilution-derived index of microcirculatory resistance (IMR) has emerged over years as the standard of reference to invasively define coronary microvascular dysfunction (CMD). However, the technique still presents some limitations, mainly related to the fact that manual injection of saline bolus accounts for some variance in the measurements. Continuous intracoronary thermodilution has been recently introduced as a tool to directly quantify absolute coronary flow and microvascular resistance both at rest and during hyperemia and has shown to be safe and operator independent. Microvascular resistance reserve (MRR), derived from continuous thermodilution, has been validated as novel index specific for microcirculation and independent from myocardial mass. Purpose To compare head-to-head the intra-observer repeatability of bolus and continuous thermodilution for assessing microvascular function. Methods Patients undergoing coronary angiography in the absence of obstructive coronary artery disease were prospectively enrolled. Bolus and continuous intracoronary thermodilution measurements were performed in duplicates in the left anterior descending artery (LAD). Patients were randomly assigned in a 1:1 ratio to undergo first bolus thermodilution or first continuous thermodilution assessment. Results A total of 102 patients were enrolled. Average FFR was 0.86±0.06. Coronary Flow Reserve (CFR) calculated with continuous thermodilution (CFRthermo) was significantly lower than bolus thermodilution-derived CFR (CFRbolus) (2.63±0.65 and 3.29±1.17, respectively, p<0.001). CFRthermo showed a lower variability and a higher agreement than CFRbolus (variability 12.74 ± 10.41% vs 31.26±24.85%, respectively, p<0.001; ICC= 0.78 (0.70-0.85) and 0.48 (0.32-0.62), respectively, p<0.001, Figure 1). Both MRR and IMR showed a good agreement (ICC 0.81 (0.74-0.87) and 0.80 (0.71-0.86)) but the variability of the MRR was significantly lower (12.44 ± 10.06% vs 24.24±19.27, respectively, p<0.001, figure 1). Reproducibility data of all indices derived from duplicated measurements of bolus and continuous thermodilution are reported in Figure 2. Conclusion Continuous intracoronary thermodilution has a higher repeatability than bolus thermodilution in the assessment of CMD.

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Aims The leading reason for delayed discharge after pulmonary vein isolation (PVI) is vascular complications. This study aimed to evaluate feasibility, safety, and efficacy of the Perclose Proglide™ suture-mediated vascular closure in ambulatory PVI, report complications, patient satisfaction, and cost of this approach. Methods and results Patients scheduled for PVI were enrolled prospectively in an observational design. Feasibility was assessed as % discharged the day of procedure. Efficacy was analysed as acute access site closure rate, time to reach haemostasis, time to ambulate, and time to discharge. Safety analysis consisted of vascular complications at 30 days. Cost analysis was reported using direct and indirect cost analysis. A 1:1 propensity matched control cohort was used for comparing time to discharge to usual workflow. Of 50 enrolled patients, 96% were discharged on the same day. 100% of devices were successfully deployed. Immediate (<1 min) haemostasis was reached in 30 patients (62.5%). Mean time to discharge was 5:48 ± 1:03 h (vs. 10:16 ± 1:21 h in the matched cohort, P < 0.0001). Patients reported high level of satisfaction with the post-operative time. No major vascular complication occurred. Cost analysis showed a neutral impact compared to the standard of care. Conclusion The use of the closure device for femoral venous access after PVI led to safe discharge of patients within 6 h from the intervention in 96% of the population. This approach could minimize the overcrowding of healthcare facilities. The gain in post-operative recovery time improved patients’ satisfaction and balanced the economic cost of the device.

Introduction The development of left ventricular hypertrophy in patients with severe aortic stenosis (AS) is accompanied by adaptive coronary flow regulation, both in epicardial and microvascular compartment, which ultimately lead to a chronic ischemic insult even in the absence of obstructive coronary artery disease. Intracoronary continuous thermodilution of saline through a dedicated infusion catheter (RayFlow ®) is a novel tool that allows to measure absolute coronary flow and microvascular resistance at rest and during hyperemia and to calculate both coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR) Purpose We aimed to assess absolute coronary flow, microvascular resistance, CFR and MRR in patients with AS, assessed by continuous intracoronary thermodilution, comparing these hemodynamic findings with a propensity-score matched contemporary cohort of patients without AS. Methods Absolute coronary blood flow and microvascular resistance were measured by continuous thermodilution in 29 patients with AS and compared to 15 controls matched for age, gender, diabetes mellitus and functional severity of epicardial coronary lesions. Myocardial work, total myocardial mass and LAD-specific mass were quantified by echocardiography and cardiac-CT. Results Patients with AS presented a significantly positive LV remodeling with lower global longitudinal strain and higher global work index compared to controls (p<0.02). Total LV myocardial mass and LAD-specific myocardial mass were significantly higher in patients with AS. Compared to matched controls, absolute resting flow in the LAD was significantly higher in the AS cohort (86 [66–107] ml/min vs 68 [52–75] ml/min, p=0.036), resulting, in lower CFR (2.30 ± 0.69 vs 2.89 ± 0.77, p=0.005) and MRR (2.73 ± 0.74 vs 3.53 ± 0.95, p=0.005) in the AS cohort compared to controls (Figure 1). No differences were found in hyperemic flow and resting and hyperemic resistances. Interestingly, hyperemic myocardial perfusion (calculated as the ratio between the absolute coronary flow subtended to the LAD and expressed in mL/min/g), but not resting, was significantly lower in the AS group (1.9 [1.5–2.5] ml/min/g vs 2.3 [2–3.1] ml/min/g p=0.036). Conclusions In patients with severe aortic stenosis and non-obstructive coronary artery disease, with the progression of LVH, the compensatory mechanism of increased resting flow maintains an adequate perfusion at rest, but not during hyperemia (Figure 2). As consequence, both CFR and MRR are significantly impaired.