Author + information
- Noriaki Moriyama, MD∗ (, )
- Futoshi Yamanaka, MD,
- Koki Shishido, MD,
- Kazuki Tobita, MD,
- Shohei Yokota, MD,
- Takahiro Hayashi, MD,
- Tatsuya Koike, MD,
- Hirokazu Miyashita, MD,
- Hiroaki Yokoyama, MD,
- Takashi Nishimoto, MD,
- Takuma Takada, MD,
- Tomoki Ochiai, MD,
- Shingo Mizuno, MD,
- Yutaka Tanaka, MD, PhD,
- Masato Murakami, MD, PhD,
- Saeko Takahashi, MD and
- Shigeru Saito, MD
- ↵∗Department of Cardiology and Catheterization Laboratories, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura, Kanagawa 247-8533, Japan
Fractional flow reserve (FFR) measurement is a well-established pressure wire-based procedure that is used to assess the functional severity of coronary lesions (1). Various randomized trials have demonstrated that FFR-guided revascularization improves clinical outcomes in patients with ischemic heart diseases (2,3). On the other hand, transradial access (TRA) is widely performed worldwide and has become the main access method. A clinical benefit to TRA, including less vascular complications and improved patient comfort, compared with the transfemoral approach, has been previously revealed (4,5). Therefore, in the TRA era, a less invasive procedure needs to be established. Although 5-F or 6-F catheter–based FFR is routinely performed, the use of much smaller catheters has not been established. Furthermore, the standard approach for measuring FFR throughout the world is still using a guiding catheter. The aim of this study was to compare the accuracy of FFR measurement via 4-F diagnostic catheters compared with that via 6-F in the same coronary lesion.
In a prospective, single-center study performed between October 2016 and May 2017, we verified the accuracy of FFR results obtained with a 4-F diagnostic catheter compared with those obtained with a 6-F diagnostic catheter. This clinical study was registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN000025089). All patients had arterial access established before the procedure using a 6-F Glidesheath Slender (Terumo, Tokyo, Japan). The COMET Pressure Guidewire (Boston Scientific, Minneapolis, Minnesota) was used in all cases. In the current study, the cutoff value for clinical significance was 0.80. If FFR measured through the 4-F diagnostic catheter was between 0.70 and 0.90, the measurement through a 6-F diagnostic catheter was evaluated.
Paired (4-F and 6-F diagnostic catheter FFR) recordings taken from 62 vessels in 61 consecutive patients were suitable for this analysis. The mean age was 70.9 ± 8.6 years. Stable angina pectoris was the presentation in 55 (90%) patients. Pressure curves obtained via a 4-F catheter were similar to those via a 6-F catheter (Figure 1A). The mean FFR values measured using the 4-F and 6-F diagnostic catheters were 0.82 ± 0.05 and 0.82 ± 0.06, respectively (p = 0.97).
Figure 1B illustrates corresponding steady-state FFR measurements for each lesion as (x, y) coordinates. The line of identity is revealed as a solid line on this graph. The majority of readings lie close to this line, indicating a good agreement between FFR values derived from the 4-F and 6-F catheters (intraclass correlation = 0.94; p < 0.001, r2 = 0.876). Figure 1C shows a Bland-Altman plot of the same data. Many cases were found in which the FFR value was actually lower when measured using a 4-F catheter than when using a 6-F catheter (represented as data points above the x-axis on the graph). There were similarly several other cases in which the converse is true. Formal evaluation of the agreement between these 2 measurements of FFR by Bland-Altman plot analysis indicated an estimated bias of −0.0038 with the 95% limit of agreement extending from −0.0088 to 0.0013, which indicates no evidence for a systemic direction of bias of FFR measurements from the two different catheters.
In this study, aortic wave distortion (loss of the dicrotic notch) was found in 3 cases but only when using the 4-F diagnostic catheters. All 3 cases had a severely tortuous innominate artery via right radial artery approach. This anatomical variation in access route could make the inner lumen of a 4-F diagnostic catheter even narrower. Also, while using a 4-F catheter it is important to carefully inspect the quality of the Pa signal and flush the catheter adequately with saline to remove all contrast.
This is the first study to report the accuracy of FFR assessment using 4-F diagnostic catheters. The quality of the pressure curves through a 4-F catheter was comparable to that observed through a 6-F catheter. This method is particularly suited to the TRA era and may become widely accepted. Larger studies are warranted to further investigate the efficacy of this promising novel method in patients requiring FFR measurement.
Please note: The authors have reported that they have no relationships related to the contents of this paper to disclose.
- 2018 American College of Cardiology Foundation