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Research connected to Cavis Wirecath pressure guide wire

Clinical studies involving Wirecath are ongoing, e.g.

Sahlgrenska, Gothenburg, Sweden Clinicaltrials#NCT04776577

Catharina, Eindhoven, The Netherlands Clinicaltrials#NCT04802681

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Clinical importance of simple and accurate CFR measurements

There is a large unmet need to diagnose patients with non-obstructive coronary artery disease (NOCAD) by measuring coronary flow reserve (CFR) (1), resistive reserve ratio (RRR) (2) or microvascular resistance reserve (MRR) (3)

 

Existing invasive tools for measuring CFR have a number of disadvantages preventing their integration into standard care. The thermodilution technique has weak test-retest reliability as manual injections cause data variability (4). The Doppler technique is highly dependent on the skill/experience of the operator and there is insufficient quality of Doppler traces in up to 30% of measurements (5).

RRR is easily derived by pressure from CFR by the formula RRR = Pd rest/Pd hyp x CFR (2).

MRR is easily derived by pressure from CFR by the formula MRR = Pa rest/Pd hyp x CFR (3).

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Pressure-derived CFR with
Cavis Wirecath

In-vitro study: Accuracy in pressure-derived CFR vs. thermodilution-CFR

Wirecath has been assessed regarding possible use for pressure-derived CFR. In a wetlab with pulsatile flow, we compared the accuracy of pressure-derived CFR using Wirecath with thermodilution-CFR using a commercially available pressure wire. CFR was overestimated by both methods to a similar extent in this in-vitro model.

Result: Pressure-derived CFR had better correlation with true CFR compared to thermodilution.

In-vitro study: Effects of focal vs. diffuse disease on accuracy in pressure-derived CFR

In the wetlab, we assessed the effects of focal versus diffuse disease on the accuracy of pressure-derived CFR.

 

Result: Accuracy was only slightly affected by the two simulated types of disease, diffuse and focal. When merging diffuse and focal data, there was a good correlation with true CFR.

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Focal stenosis
Constriction with a negative angle edge and an inner diameter of 1.7 mm

Diffuse stenosis

300 mm tube with an inner diameter of 3.2 mm

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Coronary Flow Reserve (CFR) measurements

What to do when there are no obstructive lesions?

Approximately 40% of angiography patients have non-obstructive coronary artery disease (1).

  • Rarely receive a definitive diagnosis

  • Are frequently labelled and managed inappropriately

  • Often continue to remain symptomatic

In-vitro study: Effects of hydrostatic error on accuracy in pressure-derived CFR

To simulate Pd-values with hydrostatic errors, the conservative average hydrostatic error of 1.0 mmHg (range -2 mmHg to +1 mmHg) was added randomly to Pd.

 

Result: The correlation between pressure-derived CFR and true CFR was abolished.

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Future research

Clinical research in pressure-derived CFR with Wirecath is ongoing.