Author + information
- Shingo Kato, MD, PhD∗ (, )
- Naka Saito, MT,
- Tatsuya Nakachi, MD,
- Kazuki Fukui, MD,
- Tae Iwasawa, MD,
- Masataka Taguri, PhD,
- Masami Kosuge, MD,
- Kazuo Kimura, MD and
- Kouichi Tamura, MD, PhD
- ↵∗Department of Cardiology, Kanagawa Cardiovascular and Respiratory Center, 6-16-1 Tomokahigashi, Kanazawaka, Yokohama, Kanagawa 2360051, Japan
We thank Dr. Lichtenberg for his interest and insightful comments regarding our study of the prognostic value of coronary flow reserve (CFR) evaluated by phase-contrast cine cardiac magnetic resonance imaging (MRI) of the coronary sinus to patients with known or suspected coronary artery disease (CAD) (1). We read his letter with great interest and absolutely agree with his interpretation. He mentioned the importance of resting myocardial blood flow (MBF) as the main determinant of CFR. We found that resting MBF is significantly higher in patients with major adverse cardiac events (MACEs) than in those without, in patients with known and suspected CAD (1.25 ± 0.35 vs. 0.91 ± 0.24 and 1.25 ± 0.32 vs. 0.86 ± 0.23, respectively; both p < 0.001). However, MBF during stress did not significantly differ between patients with and without MACE in both groups. One possible explanation for this is that MBF is already elevated at rest, which would account for ischemia from epicardial coronary stenosis or microvascular dysfunction or both, whereas the reserve capacity for pharmacological stress is decreased in patients with MACE. Our results are similar to those of an evaluation of coronary flow by Dr. Lichtenberg using myocardial rubidium positron emission tomography.
In this regard, evaluation of the prognostic value of resting MBF measured by phase-contrast cine MRI for CAD patients is of great interest. However, our study was designed to investigate the prognostic significance of CFR, and thus we do not yet have any prognostic data on resting MBF. A comparison of the prognostic value of resting MBF, stress MBF, and CFR for predicting MACE would be important. If resting MBF and the incidence of MACE are significantly associated, resting MBF might be a more important prognostic factor than CFR, because it can essentially be measured noninvasively without exposure to ionizing radiation or a need for gadolinium contrast injection and vasodilators. We believe that resting MBF assessed using phase-contrast cine MRI will provide new insights into the risk stratification of patients with known or suspected CAD. Further study is necessary to clarify this notion.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2017 American College of Cardiology Foundation