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.

Improvement in angina pectoris after percutaneous coronary interventions in focal and diffuse coronary artery disease

Objective

To investigate the effect of PCI on patient-reported outcomes in focal and diffuse coronary artery disease (CAD) as defined by the pullback pressure gradient (PPG).

Background

Improvements in fractional flow reserve (FFR) following PCI are associated with freedom from angina. CAD patterns influence the FFR change after stenting. Therefore, CAD patterns might be essential to assess the likelihood of PCI success in terms of angina relief.

Methods

This is a sub-analysis of the TARGET-FFR randomized clinical trial (NCT03259815). The 7-item Seattle Angina Questionnaire (SAQ-7) and EuroQol five-level EQ-5D questionnaire (EQ-5D-5L) were administered at baseline and three months after PCI. The PPG index was calculated from manual pre-PCI FFR pullbacks and the median PPG value was used to define focal and diffuse CAD.

Results

103 patients (51 with focal and 52 with diffuse disease) were analyzed. There were no differences in baseline characteristics between patients with focal and diffuse CAD. Patients with focal disease had larger increases in FFR with PCI than those with diffuse disease (0.30±0.14 units vs 0.19±0.12 units, p<0.001). Patients who underwent PCI to focal CAD had significantly higher SAQ-7 summary scores at follow-up compared to those with diffuse CAD (87.1±20.3 vs. 75.6±24.4, mean difference 11.5 [95% CI 2.8 to 20.3], p=0.01). Following PCI, residual angina was present in 39.8% of all patients but was significantly lower among those with treated focal CAD (27.5% vs 51.9%, p-value=0.020).

Conclusion

Persistent angina after PCI was almost twice as common in patients with diffuse CAD as defined by the pre-PCI PPG. Patients with focal disease reported greater improvement in angina and quality of life with PCI. The likelihood of successful angina relief from PCI can be predicted by the baseline pattern of CAD.

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 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.

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