High Occurrence of Waveform Artifacts, Signal Drift in FFR Measurements

A relatively high prevalence of fractional flow reserve (FFR) measurements may be imperfect, due to either signal drift or artifacts in the pressure wave-form, according to a core laboratory analysis published July 17 in JACC: Cardiovascular Interventions.

Mitsuaki Matsumura, BS, et al., studied 763 patients undergoing FFR assessment within the CONTRAST study. They had paired, repeated measurements of multiple physiological metrics per local practice. An independent central physiology core laboratory analyzed blinded pressure tracings off-line in a standardized fashion for comparison.

A total of 4,946 pressure tracings were analyzed by the core laboratory, including resting measurements, contrast FFR, and FFR with intracoronary or intravenous adenosine. Pull-back data were available for 616 patients (80.7 percent). Among the 4,217 tracings (n = 655) without evidence of signal drift, 222 tracings (5.3 percent) were noted to have ventricularization of the aortic waveform and 168 (4.0 percent) had aortic waveform distortion. Researchers found excellent agreement between core laboratory-calculated and site-reported FFR, with a mean difference of 0.003 ± 0.02. Predictors of distorted waveforms were smaller guiding catheter size (odds ratio, 6.30; 95 percent confidence interval, 3.22-12.32; p < 0.001) and intracoronary adenosine use (odds ratio, 0.13; 95 percent confidence interval, 0.05-0.33; p < 0.001).

According to the study authors, these findings may have important implications on clinical decision making, and attention to detail and strict standardization of methods are critical when measuring FFR to ensure optimal results.

In an accompanying editorial comment, Habib Samady, MD, FACC, and Arnav Kumar, MBBS, write that, "[b]y shedding light on the high occurrence of signal drift, guide pressure ventricularization, and other distorted aortic waveforms, the investigators have made an important contribution to the field of coronary physiology. In practice, the frequency of these errors in FFR measurements may be even higher.

Samady and Kumar offer simple steps to reduce the likelihood of technical errors while also urging industry colleagues to continue to "develop and iterate the piezoelectric sensor technology to reduce the incidence of signal drift as we use pressure wire technology for more complex disease. The recent introduction of optical sensors for FFR measurement has been a significant step forward in reducing signal drift.

Keywords: Odds Ratio, Adenosine, Confidence Intervals, Incidence, Research Personnel, Prevalence, Artifacts, Probability, Rest, Attention

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