New modalities may enhance CAD assessment

SAN FRANCISCO — Clinical trial results presented at TCT 2013 demonstrated the high accuracy of fractional flow reserve computed from noninvasive CT angiography and instantaneous wave-free ratio for the evaluation of patients with CAD.

HeartFlowNXT

In the blinded, prospective, core lab-adjudicated HeartFlowNXT trial, Bjarne L. Nørgaard, MD, PhD, of Aarhaus University Hospital, Denmark, and colleagues evaluated the accuracy of fractional flow reserve computed from noninvasive CT angiograhy (FFR_CT) in 254 patients. All were scheduled to undergo nonemergent, clinically indicated invasive angiography due to suspected CAD. The diagnostic performance of FFR_CT was compared with that of coronary CTA and invasive coronary angiography (both lumen reduction >50%) for the diagnosis and classification of hemodynamically significant stenosis, using an FFR value of ≤0.80 as the reference standard.

Results obtained with FFR_CT were similar to those obtained with invasive FFR. The area under the receiving operator characteristic curve (AUC) for FFR_CT was 0.82 vs. 0.63 for coronary CTA (P<.0001). Per-patient sensitivity and specificity were 86% and 79% for FFR_CT vs. 94% and 34% for coronary CTA, and 91% and 51% for invasive coronary angiography.

“We demonstrated high diagnostic accuracy for detection of ischemia with this new test,” Nørgaard said at a press conference. “The diagnostic performance of FFR_CTseems to outperform other existing non-invasive test modalities for assessment of coronary artery disease using FFR as the reference standard.”

ADVISE II

In the prospective, observational, nonrandomized, double blind ADVISE II study, Javier Escaned, MD, PhD, from Hospital Clinico San Carlos, Madrid, assessed the diagnostic performance of instantaneous wave-free ratio (iFR) as both a dichotomous index and in combination with FFR.

iFR was used according to specific cutoffs (iFR zone, ≤0.85 and ≥0.94. FFR use was limited to iFR values between 0.86 and 0.93.

The primary endpoint was proper classification of percentage stenosis according to hemodynamic severity (FFR value ≤0.80).

The researchers enrolled 797 patients at 40 sites in the United States, Europe and Africa for a total of 919 stenoses, 690 of which were included in the final analysis. The evaluated stenoses included 213 within the “adenosine zone,” 143 with iFR ≤0.85 and 334 with iFR ≥0.94.

Classification in terms of hemodynamic severity was accurate for 91.6% of stenoses within the iFR zone, including 88.1% (95% CI, 81.6-92.9) of those with iFR values ≤0.85 and 93.1% (95% CI, 89.8-95.6) with values ≥0.94. The iFR/FFR hybrid strategy demonstrated an overall diagnostic accuracy of 94.2%, with sensitivity, specificity, PPV and NPV values all >90%. Adenosine use was not required in 69.1% of stenoses and 65.1% of patients.

“The results of the ADVISE II study support the use of iFR to simplify physiological guidance of PCI,” Escaned stated in a press release. “The promising results demonstrate the potential of boosting the benefits of ischemia-driven revascularization to a larger proportion of patients with CAD.”

For more information:

Escaned J. Plenary session VII: Late breaking clinical trials II.

Nørgaard, BL. Plenary session VII: Late breaking clinical trials II. Both presented at: TCT 2013; Oct. 27-Nov. 1, San Francisco.

Disclosure: HeartFlow provided funding for the HeartFlowNXT study, but had no involvement in data analysis, abstract planning or preparation. The HeartFlowNXT researchers report no financial disclosures. Volcano Corporation funded the ADVISE II trial. Escaned reports speaking at educational events organized by Boston Scientific, St. Jude Medical and Volcano Corporation.