Adenosine-Free Pressure Measurement Comparable to FFR

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A new method of assessing functional coronary lesion severity that does not rely on vasodilators to induce hyperemia appears to be as accurate for diagnosing ischemia as standard fractional flow reserve (FFR) and is easier to use, according to results published online July 10, 2012, ahead of print in Circulation: Cardiovascular Interventions.

The stenosis resistance index method uses sensor-equipped guidewires to measure both distal coronary pressure and flow velocity and can be performed at both baseline—without adenosine-induced hyperemia—and maximal hyperemia via an intracoronary adenosine bolus (20-40 µg).

For the registry study, Jan J. Piek, MD, PhD, of the University of Amsterdam (Amsterdam, The Netherlands), and colleagues compared baseline and hyperemic stenosis resistance with 2 other methods. FFR and coronary flow velocity reserve measurements were taken in 232 elective PCI patients (299 lesions) with at least 1 intermediate lesion by visual assessment. Quantitative coronary angiography showed a mean diameter stenosis of 55 ± 11%.

Novel Parameter Stands up to Standard

In receiver operating characteristic analysis, hyperemic stenosis resistance yielded the highest diagnostic accuracy for myocardial ischemia (P < 0.005 compared with all other parameters). The other measurement methods, including baseline stenosis resistance, were comparable (table 1).

Table 1. Diagnostic Accuracy

 

AUC

95% CI

Baseline SR

0.77

0.71-0.83

Hyperemic SR

0.81

0.76-0.87

CFVR

0.75

0.68-0.81

FFR

0.77

0.71-0.83

Abbreviations: AUC, area under the curve; SR, stenosis resistance; CFVR, coronary flow velocity reserve.

Additionally, there was no difference in accuracy between baseline stenosis resistance and either conventional method (table 2).

Table 2. Diagnostic Accuracy Differences

 

Difference in Area Under the Curve

P Value

Baseline SR vs. FFR

0.00

0.88

Baseline SR vs. CFVR

0.02

0.52


The optimal cutoff value for baseline stenosis resistance was determined to be 0.66 mm Hg · cm –1 · sec (sensitivity 64%, specificity 80%). Diagnostic accuracy of baseline SR was similar to both FFR with a cutoff value of 0.75 (P = 0.58) and coronary flow velocity reserve (P = 0.28) and was higher compared with FFR with a cutoff value of 0.80 (P = 0.001).

Confirmation Needed

“Based on the fact that an index of stenosis resistance is [by] definition less dependent on achieving maximal hyperemia, we hypothesized that the diagnostic accuracy of baseline stenosis resistance index would be sufficient for this parameter to be used for functional lesion severity assessment,” Dr. Piek told TCTMD in an e-mail communication. “However, it was surprising to find that the accuracy of [baseline stenosis resistance] was similar to the widely used FFR and less adopted [coronary flow velocity reserve] when compared to an independent gold standard, which makes [baseline stenosis resistance] a very interesting parameter that should be investigated further.”

This novel method has the potential to improve patient outcomes, he continued, as it is the only measurement “to date that does not depend on the use of a vasodilator that has been shown to be of comparable diagnostic accuracy compared with the currently adopted parameters.”

Still, future research is warranted before use of baseline stenosis resistance becomes routine, Dr. Piek observed. “Little is known about the actual effectiveness for guidance of PCI,” he cautioned, adding that he would like to see prospective studies further evaluate diagnostic accuracy of baseline stenosis resistance according to the cutoff value determined in the current study.

“Moreover, clinical outcome studies are necessary prior to adoption of the technique in daily clinical practice,” he concluded.

 


Source:
van de Hoef TP, Nolte F, Damman P, et al. Diagnostic accuracy of combined intracoronary pressure and flow velocity information during baseline conditions: Adenosine-free assessment of functional coronary lesion severity. Circ Cardiovasc Interv. 2012;Epub ahead of print.

 

 

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Disclosures
  • Dr. Piek reports no relevant conflicts of interest.

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