Author + information
- Seung-Jung Park, MD, PhD∗ (, )
- Soo-Jin Kang, MD, PhD and
- Jung-Min Ahn, MD
- ↵∗Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, South Korea
We thank Dr. de la Torre Hernández and colleagues for their interest in our paper (1) suggesting the optimal left main coronary artery minimal lumen area (LM-MLA) of 4.5 mm2 for detecting fractional flow reserve (FFR) <0.80.
First, the Jasti et al. (2) study with a small sample size (N = 55) reporting an LM-MLA cutoff value of 5.9 mm2 enrolled patients with lesions with downstream disease of the LM branches; 58% were distal LM lesions usually extending to the side-branch ostia, which made assessing how the LM-MLA itself affects the hemodynamic significance unreliable. Moreover, they included only a few patients with an MLA of 4.5 to 6.0 mm2. The lesions mostly had a large lumen, with 75% having a negative FFR. Conversely, our study (N = 112) included only ostial and shaft lesions: 34 patients with an LM-MLA of 4.5 to 6.0 mm2 and more ischemia-inducing lesions and 59% with positive FFR (<0.80). That is the main difference in our study. The ethnic differences poorly supported the relevance of using the larger LM-MLA criterion. Rusinova et al. (3) reported a smaller LM-MLA in Asian patients, whereas the vessel area was greater in Asian compared with North American patients (20.7 ± 4.5 mm2 vs. 19.3 ± 4.2 mm2, p = 0.024).
Second, the suboptimal accuracy of the LM-MLA is not surprising. Even in isolated LM lesions, the FFR was determined not only by the LM-MLA but also by various clinical and lesion-specific local factors (age, body mass index, left ventricular mass, and the presence of plaque rupture) (1). In patients with an LM-MLA >4.5 mm2, the FFR was <0.80 in 24%, but <0.75 in only 9%. However, 36% of the patients with an LM-MLA <6.0 mm2 showed an FFR >0.80, and they are at risk of undergoing unnecessary treatment.
Third, if an MLA of 3.0 mm2 for the left anterior descending artery and 2.7 mm2 for the left circumflex artery are assumed to be ischemic thresholds, clearly the LM-MLA is 4.5 mm2 (Murray’s law) (1).
Fourth, in the LITRO trial (4), 16 of the 168 patients with an LM MLA <6 mm2 did not undergo revascularization. They had an LM-MLA of 5.0 to 6.0 mm2 and had complex lesion morphology for PCI, high surgical risk, old age, and multiple comorbidities. The worse outcome in those ineligible for the protocol could not represent the general population.
Finally, no evidence-based criteria warrant revascularization for vulnerable lesions without ischemia. The FFR is the most sensitive index of ischemia in all clinical settings except ST-segment elevation myocardial infarction. Thus, LM-MLA may be useful to aid in decision making as to whether to treat, but choose the cutoff value wisely! If you still doubt about objective ischemia, please use the FFR!
- American College of Cardiology Foundation
- Park S.J.,
- Ahn J.M.,
- Kang S.J.,
- et al.
- Jasti V.,
- Ivan E.,
- Yalamanchili V.,
- Wongpraparut N.,
- Leesar M.A.
- de la Torre Hernandez J.M.,
- Hernandez Hernandez F.,
- Alfonso F.,
- et al.