Assessment of absolute coronary flow and microvascular resistance reserve in patients with severe aortic stenosis

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 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, 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 in the LAD and the mass subtended by the vessel, 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.

Funding Acknowledgement

Type of funding sources: None.

Diagnostic and prognostic role of cardiac magnetic resonance in patients with MINOCA

Background

Myocardial infarction with non-obstructed coronary arteries (MINOCA) is common in current clinical practice and cardiac magnetic resonance (CMR) plays an important role in the present management of this group of patients. However, there are still a lot of controversies concerning the etiology behind the syndrome of MINOCA. Furthermore, the prognostic value of CMR in patients with MINOCA is still undetermined.

Purpose

We aimed to determine the diagnostic and prognostic value of CMR in the management of patients with MINOCA.

Methods

A systematic review was performed to identify studies reporting the results of CMR findings in MINOCA patients (non-obstructive CAD or normal coronary arteries). Random effects models were used to determine the prevalence of different disease entities – myocarditis, myocardial infarction, Takotsubo cardiomyopathy or normal CMR findings. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the prognostic value of CMR diagnosis in the subgroup of studies that reported clinical outcomes. Major adverse clinical events (MACE) were defined based on the specific study definitions and included cardiovascular death, non-fatal myocardial infarction, and cardiovascular hospitalization.

Results

31 studies comprising 4119 patients were included. Mean age was 54.1±3.3, 59% were males. The pooled prevalence of myocarditis was 32% (95% CI 0.25 to 0.39), myocardial infarction (MI) - 21% (95% CI 0.17 to 0.24), Takotsubo cardiomyopathy −12% (95% CI 0.09 to 0.16). Normal findings were found in 23% (95% CI 0.14 to 0.35), figure 1. In a subgroup analysis of seven studies (900 patients) that reported clinical outcomes the prognostic value of the CMR was assessed. CMR diagnosis of myocarditis was not significantly associated with increased risk of MACE (pooled OR, 1.50; 95% CI, 0.46 to 4.87; p=0.459). However, both diagnosis of MI and Takotsubo were significantly associated with increased risk of combined clinical outcomes (pooled OR, 1.75; 95% CI, 1.12 to 3.59; p<0.05 and pooled OR, 2.19; 95% CI, 1.34 to 5.27; p<0.001).

Conclusion

In patients with MINOCA CMR brings important diagnostic and prognostic role. The pooled prevalence of myocarditis was 32%, of MI – 21% and of Takotsubo – 12%. The CMR diagnosis of MI and Takotsubo was associated with increased risk of MACE.

Funding Acknowledgement

Type of funding sources: None.

Repeatability of bolus and continuous thermodilution for assessing coronary microvasculatory function

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 Table 2.

Conclusion

Continuous intracoronary thermodilution has a higher repeatability than bolus thermodilution in the assessment of CMD.

Funding Acknowledgement

Type of funding sources: None.

Impact of aortic regurgitation on long-term outcomes in heart failure with preserved ejection fraction

Background

Aortic Regurgitation (AR) may aggravate the clinical course in patients with heart failure and preserved ejection fraction (HFpEF) by increasing filling pressures and triggering LV remodelling.

Objective

To assess AR's prevalence and long-term prognostic implications in patients with HFpEF.

Methods

The study population consisted of 458 consecutive patients (age 77.5±9.2 y, 57.9% females) hospitalized with de novo or worsened HFpEF. Patients with more than moderate aortic and/or mitral valve disease were excluded. Data on cardiovascular death, HF re-hospitalization and their composite (MACE) were collected.

Results

Out of 309 (67.5%) patients with any AR, 156 (34.0%) and 153 (33.5%) had mild-AR and moderate-AR, respectively. The remaining 149 (32.5%) individuals had no-AR. Patients with versus without AR were significantly older with larger LV and LA volumes and a higher prevalence of diastolic dysfunction (all p<0.05). During a median follow-up of 33±25 months, a total of 114 patients (24.9%) died from cardiovascular causes, 126 patients (27.5%) were re-hospitalized for HF, while 272 (59.4%) had the composite endpoint (MACE). In multivariable Cox regression analysis, any AR emerged as an only independent predictor of MACE (HR=1.90, 95% CI 1.26–2.87, p=0.002). Mild-AR and Moderate AR increased the risk of MACE by 77% and 92%, respectively, compared to the No-AR (Figure).

Conclusions

In patients with HFpEF, mild-to-moderate AR is highly prevalent, and it seems to identify individuals with worse long-term outcomes. This suggests that even mild AR should be considered a high-risk prognostic marker in patients with HFpEF.

Funding Acknowledgement

Type of funding sources: None.

Saline-induced coronary hyperemia with continuous intracoronary thermodilution is mediated by intravascular hemolysis

Objectives

To test whether local hemolysis is a potential mechanism of saline-induced coronary hyperemia.

Background

Absolute coronary flow can be measured by intracoronary continuous thermodilution of saline through the lateral side holes of a dedicated infusion cathete. A saline infusion rate at 15–20 mL/min induces an immediate, steady-state, maximal microvascular vasodilation. The mechanism of this hyperemic response remains unclear.

Methods

Twelve patients undergoing left and right catheterization were included. The left coronary artery and the coronary sinus were selectively cannulated. Absolute resting and hyperemic coronary flow were measured by continuous intracoronary thermodilution. Arterial and venous samples were collected from the coronary artery and the coronary sinus in five phases: baseline (BL); resting flow measurement (Rest, saline infusion at 10 mL/min); hyperemia (Hyperemia,saline infusion at 20 mL/min); post-hyperemia (Post-Hyperemia, two minutes after the cessation of saline infusion); and control phase (Control, during infusion of saline through the guide catheter at 30 mL/min).

Results

Hemolysis was visually detected only in the centrifugated venous blood samples collected during the Hyperemia phase. As compared to Rest, during Hyperemia both LDH (131.50±21.89 U/dL [Rest] and 258.33±57.40 U/dL [Hyperemia], p<0.001) and plasma free hemoglobin (PFHb, 4.92±3.82 mg/dL [Rest] and 108.42±46.58 mg/dL [Hyperemia], p<0.001) significantly increased in the coronary sinus. The percentage of hemolysis was significantly higher during the Hyperemia phase (0.04±0.02% [Rest] vs 0.89±0.34% [Hyperemia], p<0.001).

Conclusions

Saline-induced hyperemia through a dedicated intracoronary infusion catheter is associated with hemolysis. Vasodilatory compounds released locally, like ATP, are likely ultimately responsible for localized microvascular vasodilation.

Funding Acknowledgement

Type of funding sources: None.

Infarct size, inflammatory burden and admission hyperglycemia in diabetic patients with acute myocardial infarction treated with SGLT2-inhibitors: a multicenter international registry

Background

Sodium-glucose co-transporter 2 inhibitors (SGLT2-I) currently receive intense clinical interest in patients with and without diabetes mellitus (DM) with pleiotropic beneficial effects. Nowadays, the inflammation response in the setting of acute myocardial infarction (AMI) has been proposed as a potential pharmacological intervention target. In this setting, we tested the hypothesis that the SGLT2-I displays anti-inflammatory effect along with glucose-lowering properties. We investigated the relationship between stress hyperglycemia, inflammation burden and infarct size in a cohort of type 2 diabetic AMI patients treated with SGLT2-I versus other oral anti-diabetic (OAD) agents alone.

Methods

In this multicenter international registry, all diabetic patients with AMI treated with percutaneous coronary intervention (PCI) between 2018 and 2021 were enrolled. Based on the admission anti-diabetic therapy, patients were divided into those receiving SGLT2-I versus other OAD agents alone. Patients on insulin therapy alone or combined with OAD agents were excluded from the study. The following inflammatory markers were evaluated at different time points: total white blood cell, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and neutrophil-to-platelet ratio (NPR), C-reactive protein. Infarct size was assessed by peak troponin levels and echocardiographic parameters.

Results

The final study population consisted of 583 patients hospitalized for AMI (both STEMI and NSTEMI) classified as SGLT2-I users (n=98) versus other OAD agents alone (n=485). Admission hyperglycemia was more prevalent among the other OAD agents group. Reduced infarct size was detected in patients treated with SGLT2-I compared to those treated with other OAD agents alone. Both at admission, and after 24 hours, inflammatory indices were significantly higher in patients treated with other OAD agents alone, with a significant increase in neutrophils levels at 24 hours, compared to the SGLT2-I group. In multivariate analysis, SGLT2-I emerged as a significant predictor of reduced inflammatory response (OR 0.45, 95% CI 0.27–0.75, p=0.002), together with peak troponin values, independently of age, admission creatinine values and admission glycemia.

Conclusions

Type 2 Diabetic patients hospitalized for AMI and receiving SGLT2-I exhibited modest inflammatory response and myocardial damage/infarct size compared to other OAD agents alone, independently of glucose-metabolic control. Our findings pave the way for new pathophysiological and therapeutic insights regarding the cardioprotective effect of SGLT2-I in the setting of coronary artery disease.

Funding Acknowledgement

Type of funding sources: None.

Outcomes benefit in asymptomatic patients with moderate aortic valve stenosis followed up in heart valve clinics

Background

The management of patients with asymptomatic moderate aortic stenosis (AS), particularly the follow-up and the choice between early intervention vs watchful waiting, remains debated. A progressively increasing number of patients with valvular heart disease (VHD) were diagnosed and followed in an ambulatory setting with a dedicated cardiologist and cardiac imaging specialist: the Heart Valve Clinics (HVC). However, the number of patients with VHD is that high, that these patients are also followed by routine cardiac care consultations (standard-of-care).

Purpose

To determine the benefit of a HVC approach and outcomes compared to standard-of-care for patients with moderate asymptomatic AS.

Methods

From November 2014 a HVC environment was introduced at our Cardiovascular Center, to follow patients with moderate and severe VHD by an imaging and valve specialist. Patients who received at least one visit in the Ambulatory HVC were included in a prospective registry. All consecutive patients with aortic valve velocity max>3 cm/sec diagnosed with 2-D echocardiography according to the ESC Guidelines were included in this study. Exclusion criteria included more than moderate aortic regurgitation and prior aortic valve replacement (AVR). Natural history, need for AVR, and survival of patients with baseline moderate AS were assessed at follow up. Cox proportional hazard model, Kaplan-Meier survival curves and propensity score matching where used to assess the HVC approach effect on the mortality.

Results

A total of 2130 patients were included (1879 in the standard-of-care group and 251 in the Ambulatory HVC group). 1187 (55.7%) were male, and the mean (SD) age was 77.2±12.2 years. A total of 919 patients (43.1%) had severe AS (aortic valve area <1.0 cm2). Mean clinical follow-up was 1.2±2.4 years. A total of 822 patients (38.6%) died during the follow up and 114 patients (55.6%) underwent AVR during the study period. After using 1:1, nearest neighbour, without replacement propensity score matching, baseline characteristics between the two groups were balanced. The introduction of Ambulatory HVC was associated with a reduction of adjusted all-cause mortality compared to the standard-of-care group (HR=0.53, 95% CI 0.35–0.82, p=0.004) (Figure1). At multivariable analysis, the Ambulatory HVC pathway was a significant predictor of reduced all-cause of death (HR=0.46, 95% CI 0.33–0.65, p<0.001), together with younger age and higher GFR, independently of AVA, tricuspid regurgitation gradient, LVEF and chronic obstructive pulmonary disease.

Conclusions

Patients with moderate AS followed up in HVC had lower rate of all-cause of death compared to the standard-of-care group. The Ambulatory HVC was a significant predictor of reduced all-cause of death and was associated with more efficient patient management and lower mortality. Dedicated HVC have the potential to improve patient care and clinical outcomes.

Funding Acknowledgement

Type of funding sources: None.

Microvascular dysfunction in patients with diabetes mellitus: assessment of absolute coronary flow and microvascular resistance reserve

Background

Coronary microvascular dysfunction (CMD) is an early feature of diabetic cardiomyopathy, which usually precedes the onset of systolic and diastolic dysfunction (DDF). Continuous intracoronary thermodilution allows an accurate and reproducible assessment of absolute coronary blood flow and microvascular resistance thus allowing the evaluation of coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR), a novel index specific for microvascular function, which is independent from the myocardial mass. In the present study we compared absolute coronary flow and resistance, CFR and MRR assessed by continuous intracoronary thermodilution in diabetic versus non-diabetic patients. Left atrial reservoir strain (LASr), an early marker of DDF was compared between the two groups.

Methods

In this observational retrospective study, 108 patients with suspected angina and non-obstructive coronary artery disease (NOCAD) consecutively undergoing elective coronary angiography (CAG) from September 2018 to June 2021 were enrolled. The invasive functional assessment of microvascular function was performed in the left anterior descending artery (LAD) with intracoronary continuous thermodilution. Patients were classified according to the presence of DM. Absolute resting and hyperemic coronary flow (in mL/min) and resistance (in WU) were compared between the two cohorts. FFR was measured to assess coronary epicardial lesions, while CFR and MRR were calculated to assess microvascular function. LAS, assessed by speckle tracking echocardiography, was used to detect early myocardial structural changes potentially associated with microvascular dysfunction.

Results

The median FFR value was 0.83 [0.79–0.87] without any significant difference between the two groups. Absolute resting and hyperemic flow in the left anterior descending coronary were similar between diabetic and non-diabetic patients. Similarly, resting and hyperemic resistances did not change significantly between the two groups. In the DM cohort the CFR and MRR were significantly lower compared to the control group (CFR=2.4±0.6 and 2.9±0.8; MRR=2.8±0.9 and 3.5±1 for diabetic and non-diabetic patients respectively, [p<0.05 for both], Figure 1 and 2). Likewise, diabetic patients had a significantly lower reservoir, contractile and conductive LAS (all p<0.05).

Conclusions

Compared with non-diabetic patients, CFR and MRR were lower in patients with DM and non-obstructive epicardial coronary arteries, while both resting and hyperemic coronary flow and resistance were similar. LASr was lower in diabetic patients, confirming the presence of a subclinical DDF associated to the microcirculatory impairment. Continuous intracoronary thermodilution-derived indexes provide a reliable and operator-independent assessment of coronary macro- and microvasculature and might potentially facilitate widespread clinical adoption of invasive physiologic assessment of suspected microvascular disease.

Funding Acknowledgement

Type of funding sources: None.

Performance of non-invasive myocardial work to predict the first hospitalization for de novo heart failure with preserved ejection fraction (HFpEF)

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Dr. Paolisso, Dr. Esposito, Dr. Fabbricatore are supported by a research grant from the CardioPaTh PhD Program of University of Naples Federico II

Background

Non-invasive myocardial work (MW) is a validated index of left ventricular (LV) systolic performance, incorporating afterload and myocardial metabolism. The role of MW in predicting the first hospitalization for de novo heart failure with preserved ejection fraction (HFpEF) is still unknown.

Purpose

To investigate the diagnostic performance of MW to predict the first de novo HFpEF hospitalization in ambulatory individuals with preserved LVEF.

Methods

Twenty-nine patients with trans-thoracic echocardiography performed at least 6 months before the first HFpEF hospitalization were compared with 29 matched controls. MW was derived as the area of pressure-strain loop using speckle-tracking and brachial artery blood pressure. Global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE) were collected. First HFpEF hospitalization and its combination with cardiovascular death (MACE) and all-cause of death (MAE) were assessed.

Results

At baseline, future HFpEF patients showed lower GWI, GCW, GWE and higher GWW than controls (all p < 0.05).  At admission versus baseline, GWE significantly decreased, and GWW increased in the HFpEF group (p < 0.05), whereas no significant difference was observed in the controls over time. GWW, with a cut-off of 170 mmHg%, showed the largest AUC to predict first HFpEF hospitalization (AUC = 0.80, 95% CI 0.69–0.91, p < 0.001), MACE (AUC = 0.80, 95% CI 0.66–0.90, p < 0.001) and MAE (AUC = 0.79, 95% CI 0.62–0.88, p = 0.001). GWW > 170 mmHg% was associated with a 4-fold increase of MACE (HR = 4.5, 95% CI 1.59–13.12, p = 0.005) and a 3-fold higher risk of MAE (HR = 2.9, 95% CI 1.24–6.6, p = 0.014).

Conclusions

In ambulatory patients with preserved LVEF and risk factors, GWW showed high accuracy to predict the first HFpEF hospitalization and its combination with mortality. The GWW routine assessment may be clinically helpful in patients with dyspnea. Abstract Figure 1: Serial changes of LARs, LV GLS  Abstract Figure 2:Kaplan–Meier survival curves fo

Physiological and angiographic outcomes of PCI in calcified lesions after rotational atherectomy or intravascular lithotripsy

BACKGROUND

Percutaneous coronary interventions (PCI) in calcified coronary artery lesions are associated with impaired stent expansion, higher rate of periprocedural complications and cardiac mortality. Lesion preparation using calcium modifying techniques such as Rotational Atherectomy (RA) or Intravascular Lithotripsy (IVL) has been advocated. Studies comparing these technologies are lacking. We aimed to compare the in-stent pressure gradient, evaluated by virtual fractional flow-reserve, in calcific lesions treated using either RA or IVL.

METHODS

Patients undergoing either RA- or IVL-assisted PCI from two European centers were included. Propensity score matching (1:2) was performed to control for potential bias. Primary outcome was post- PCI in-stent pressure gradient calculated by virtual fractional flow reserve (vFFRgrad). Secondary outcomes included the proportion of patients with complete functional revascularization defined as of distal vFFR post PCI (vFFRpost) ≥ 0.90.

RESULTS

From a cohort of 210 patients, 105 matched patients (70 RA and 35 IVL) were included. Pre-PCI vFFR did not differ between groups (0,65 ± 0,13 RA and 0,67 ± 0,11 IVL). After PCI, in-stent pressure gradients were significantly lower in the IVL group (0.032 ± 0.026 vs 0.043 ± 0.026 in the RA group, p = 0.024). The proportions of vessels with functional complete revascularization was similar between the two groups (32.9% vs. 37.1% in the RA and IVL group, respectively; p = 0.669).

CONCLUSIONS

Calcific lesions preparation with IVL is effective and resulted in improved in-stent pressure gradient compared to RA. Approximately one third of the patients undergoing PCI for a severely calcified lesion achieved functional revascularization with no difference between rotational RA and IVL.

Angiography vs physiology-based deferral of revascularization in patients with reduced left ventricular ejection fraction: a 10-year clinical follow-up

Background

Deferring percutaneous coronary intervention (PCI) in patients with non-ischemic coronary stenoses based on fractional flow reserve (FFR) and preserved left ventricular ejection fraction (LVEF) is associated with favorable long-term clinical outcomes. In patients with reduced LVEF, the role of reversible/residual ischemia in deferring revascularization is still debated.

Purpose

To investigate whether FFR provides additive clinical benefit compared to coronary angiography in deferring revascularization in patients with intermediate coronary stenoses and reduced LVEF.

Methods

Among 4577 coronary angiographies performed between 2002 and 2010, consecutive patients with reduced LVEF (≤50%) and at least one intermediate coronary stenosis [diameter stenosis (DS)% 40–70%] in whom revascularization was deferred based either on FFR (FFR-guided) or angiography (Angiography-guided) were screened. The primary endpoint of the study was cumulative incidence of death at 10 years.

Results

A total of 843 patients were included (209 in the FFR-guided and 634 in the Angio-guided group). Median clinical follow-up was 7.1 years (IQR 3.2–11.2 years). After 1:1 propensity score matching, baseline characteristics between the two groups were similar. All-cause death at 10 years was significantly lower in the FFR-guided compared with the Angiography-guided group (94 [45%] vs 115 [55%], HR 0.72 [95% CI 0.55–0.95], p<0.05). Similarly, the incidence of major adverse cardiovascular and cerebrovascular events (MACCE, composite of all-cause death, myocardial infarction, any revascularization and stroke) was lower in the FFR guided group (125 [60%] vs 140 [67%], HR 0.77 [95% CI 0.61–0.98], p<0.05).

Conclusions

In patients with reduced LVEF and associated coronary artery disease, deferring revascularization of intermediate stenoses based on FFR is associated with lower incidence of death and MACCE at 10 years.

Funding Acknowledgement

Type of funding sources: None.

Physiological and angiographic outcomes of PCI in calcified lesions after rotational atherectomy or intravascular lithotripsy

Background

Percutaneous coronary interventions (PCI) in calcified coronary artery lesions is associated with impaired stent expansion, higher rate of periprocedural complications and cardiac mortality. Lesion preparation using dedicated calcium modifying techniques such as RA or IVL has been advocated. Studies comparing these technologies are lacking.

Objectives

To compare the in-stent pressure gradient, evaluated by virtual fractional flow-reserve, in calcific lesions treated using either rotational atherectomy (RA) or intravascular lithotripsy (IVL).

Methods

Patients undergoing either RA- or IVL-assisted PCI from two European centers were included. Propensity score matching (1:2) was performed to control for potential bias. Primary outcome was post- PCI in-stent pressure gradient calculated by virtual fractional flow reserve (vFFRgrad, calculated as the difference between the vFFR at the proximal minus distal edge of the stent). Secondary outcomes included the proportion of patients with complete functional revascularization defined as of distal vFFR post PCI (vFFRpost) ≥0.90.

Results

From a cohort of 210 patients, 105 matched patients (70 RA and 35 IVL) were included. Pre-PCI vFFR did not differ between groups (0,65±0,13 RA and 0,67±0,11 IVL). After PCI, in-stent pressure gradient was significantly lower in the IVL group (0.032±0.026 vs 0.043±0.026 in the RA group, p=0.024). The proportion of vessels with functional complete revascularization was similar between the two groups (32.9% vs. 37.1% in the RA and IVL group, respectively; p=0.669)

Conclusions

Calcific lesions preparation with IVL is effective and resulted in improved in-stent pressure gradient compared to RA. Approximately one third of the patients undergoing PCI for a severely calcified lesion achieved functional revascularization with no difference between rotational RA and IVL.

Funding Acknowledgement

Type of funding sources: None. In stent gradients after RA and IVL

Quantifying coronary microvascular disease: assessing absolute microvascular resistance reserve (MRR) by continuous coronary thermodilution

Background and aim

Hyperemic absolute coronary blood flow (in mL/min) can be safely and reproducibly measured with intracoronary continuous thermodilution of saline at room temperature at an infusion rate of 20 mL/min. This study aims at assessing whether continuous thermodilution can also measure resting flow and microvascular resistance.

Methods and results

In 87 coronary arteries (58 patients) with angiographic non-significant stenoses absolute flow was assessed by continuous thermodilution of saline at infusion rates of 10 mL/min and 20 mL/min using a pressure/temperature sensored guide wire, a dedicated infusion catheter and a dedicated software. In addition, in 26 arteries, average peak velocity (APV) was measured simultaneously using an intracoronary Doppler-wire.

There was no significant difference between Pd/Pa at baseline and during saline infusion at 10 mL/min, (0.95±0.053 vs 0.94±0.054, respectively (p=0.53) and there was no significant difference in APV at baseline and during the infusion of saline at 10 mL/min (22.2±8.40 vs 23.2±8.39 cm/s, respectively, p=0.63), thus indicating presence of resting coronary blood flow during the infusion of 10 mL/min of saline.

In contrast, at an infusion rate of 20 mL/min, a significant decrease in Pd/Pa was observed compared to baseline: (0.85±0.089 vs 0.95±0.053, respectively, p<0.001) and a significant increase in APV was observed (22.2±8.4 cm/s to 57.8±25.5 cm/s, respectively, p<0.001). The coronary flow reserve (CFR) calculated by thermodilution and by Doppler flow velocity were similar (2.73±0.85 vs 2.72±1.07, respectively) and their individual values correlated closely (r=0.87, 95% CI 0.72–0.94, p<0,001). Microvascular resistance (Rμ), defined as the distal coronary pressure divided by the absolute flow was calculated both at rest (Rμ-rest) and during hyperemia (Rμ-hyper). Microvascular Resistance Reserve (MRR), is calculated as the ratio of Rμ-rest and Rμ-hyper and showed a good correlation with the analogous Doppler-derived parameter (using the APV instead of absolute flow). Mean doppler and thermodilution derived MRR were similar (3.32±1.50 vs 3.23±1.16) and values correlated closely (r=0.91, 95% CI 0.81 - 0.96, p<0.001; Bland-Altman analysis: mean bias = 0.071, limit of agreement −1.195 to 1.338).

Conclusion

Absolute coronary blood flow (in mL/min) can be measured by continuous thermodilution both at rest and during hyperemia. This allows accurate, reproducible, and operator-independent direct volumetric calculation of CFR and MRR. The latter is a quantitative metric which is specific for microvascular function and independent from myocardial mass.

Doppler and Thermodilution derived MRR

Funding Acknowledgement

Type of funding source: None

Thermodilution-derived resting coronary flow measurement: “a reverse dose finding study”

Background

Hyperemic absolute coronary blood flow (in mL/min) can be safely and reproducibly measured with intracoronary continuous thermodilution of saline at room temperature at an infusion rate of 20 mL/min. This study aims at assessing the best infusion rate to measure resting flow by thermodilution, i.e. low enough to avoid microvascular dilation but high enough to allow reliable thermodilution tracings

Methods and results

In 26 coronary arteries (24 patients) with angiographic non-significant stenoses, absolute flow was assessed by continuous saline thermodilution at infusion rates of 10 mL/min and 20 mL/min using a pressure/temperature sensored guide wire, a dedicated infusion catheter and a dedicated software. Average peak velocity (APV) was measured simultaneously using an intracoronary Doppler-wire. In addition, in a subgroup of 10 arteries, absolute flow and APV were also measured during saline infusion at 6 ml/min and 8 ml/min.

In 26 coronary arteries there was no significance difference in the Pd/Pa and in the APV at baseline and during the infusion of saline at 10 ml/min (Pd/Pa: 0.94±0.057 vs 0.94±0.059, p=0.82; APV: 22.2±8.40 vs 23.2±8.39 cm/s, p=0.63). In contrast, at an infusion rate of 20 mL/min, we observed a significant decrease in Pd/Pa compared to baseline (0.85±0.089 vs 0.95±0.053 vs, respectively, p<0.001) and a significant increase in APV (22.2±8.4 cm/s to 57.8±25.5 cm/s, respectively, p<0.001). The coronary flow reserve (CFR) evaluated by Doppler and intracoronary continuous thermodilution correlated well (r=0.87, 95% CI = 0.72–0.94, p<0.001) and Bland-Altman analysis documented a mean bias of −0.003 (limit of agreement −1.05 to 1.04) thus indicating the presence of resting coronary blood flow during the infusion of 10 mL/min of saline. In 10 coronary arteries saline infusions at 6 and 8 ml/min did not produce any significant changes in the Pd/Pa and in the APV compared to baseline and both Doppler and Thermodilution derived CFR correlated well at each infusion rate (6 ml/min: r=0.71, 95% CI 0.14–0.92, p=0.02; 8ml/min: r=0.78, 95% CI=0.31–0.95, p=0.007). However, with an infusion rate of 6 mL/min, an unstable thermodilution tracing was observed. Accordingly, Bland-Altman analysis showed a significantly larger dispersion of the CFR values when 6 ml/min was used to measure resting coronary flow (as compared with 8 m/min): mean bias at 6 ml/min: −0.53, limits of agreement: −2.25 to 1.20: mean bias at 8 ml/min: 0.004, limits of agreement: −0.72 to 0.73.

Conclusion

Absolute resting coronary flow can be measured by intracoronary continuous thermodilution of saline at infusion rate of 8–10 ml/min.

Funding Acknowledgement

Type of funding source: None

Hyperemic hemodynamic characteristics of serial coronary lesions assessed by pressure pullbacks gradients (PPG) index

Introduction

The evaluation of functional significance in serial coronary lesions is crucial for achieving optimal clinical outcomes. In this setting, fractional flow reserve (FFR) measurements with pullback pressure recording can be helpful in assessing lesion functional significance.

Purpose

To describe the functional characteristics of angiography-defined serial coronary lesions using FFR-derived motorised pullback tracings, and to describe the Pullback Pressure Gradients (PPG) index - in these lesions.

Methods

Prospective, multicentre study with independent core laboratory analysis. Patients undergoing coronary angiography due to stable angina were enrolled. Serial lesions were defined angiographically as the presence of 2 or more narrowings with visual diameter stenosis >50% separated at least by 3 times the reference vessel diameter in the same coronary vessel. Continuous IV adenosine-FFR measurements were obtained using a motorised device at a speed of 1 mm/s. Pullback curves were assessed to determine the presence of focal step-ups (FFR >0.05 units over 20 mm). In addition, the PPGindex was computed for all vessels. PPGindex values close to 0 define functional diffuse disease whereas values close to 1 define focal disease.

Results

From a total of 159 vessels (117 patients), 25 vessels were adjudicated as presenting serial lesions (mean PPGindex 0.48±0.17, range 0.26–0.87). Two focal pressure step-ups were observed in 40% of the cases (n=10; mean PPGindex 0.59±0.17), whereas 8% of the vessels presented a progressive pressure losses (n=2; mean PPGindex 0.27±0.01). In the remaining 52% of the cases, a single pressure step-up was recorded (n=13; mean PPGindex 0.44±0.12; ANOVA p-value = 0.01). The PPGindex independently predicted the presence of two focal pressure step ups.

Conclusion

Hyperemic FFR curves in tandem stenoses revealed high prevalence of functional diffuse CAD. Two pressure step-ups occurred in less than half of the vessels. High PPG-Index identified vessels with two focal pressure drops. FFR tracings and the PPGindex provide a more objective CAD evaluation, which can lead to changes in the therapeutic approach.

Funding Acknowledgement

Type of funding source: None