Author + information
- Kazuo Eguchi, MD, PhD∗ (, )
- Michiaki Hiroe, MD, PhD and
- Kazuomi Kario, MD, PhD
- ↵∗Jichi Medical University, Cardiovascular Medicine, 3311-1 Yakushiji, Shimotsuke, Tochigi-ken 329-0498, Japan
Cardiac positron emission tomography (PET) is now one of the most important diagnostic tools for the assessment of cardiac sarcoidosis (CS). The diagnostic accuracy of PET has been reported to exhibit 100% sensitivity and 80% to 90% specificity (1,2). In a recent issue of the Journal, Blankstein et al. (3) demonstrated that the presence of focal perfusion defect and F-18 fluorodeoxyglucose (FDG) uptake on cardiac PET identified patients at higher risk of death or ventricular tachycardia (VT). The focal FDG uptake in the right ventricle was also a very specific finding of CS. Although the results are interesting, there are several problems in the paper that should be acknowledged.
The first issue is the lack of an evaluation of treatment before and after the diagnosis of CS. With effective anti-inflammatory treatment, the FDG uptake on PET will be diminished, but if the extent of inflammation is advanced, only a partial effect can be obtained. The relationship between PET and treatment should thus be clarified.
The second issue relates to the Japanese Ministry of Health and Welfare guidelines. Reference 6 in the original article by Kida et al. 2013 is not appropriate as a reference for these guidelines; it is simply a small clinical study of cardiac magnetic resonance imaging. The quoted guideline is an older version of the guideline in reference (4) by Hiraga et al. 1993, which was revised in 2006, and the clinical diagnosis group was newly set as a diagnostic criterion (5). It would therefore be interesting to compare both clinical and histological diagnoses by using the 2006 Japanese guidelines.
Third, regarding the baseline characteristics of the patients (Table 1 ), 90% of the patients with adverse events had an implantable cardioverter-defibrillator (ICD) at baseline or on follow-up. Of 31 outcomes, there were 28 VT events. The reasons for the ICD implantations at baseline should be described because VT events tend to occur in patients with ICDs.
Fourth, the fasting time of 3 h is apparently insufficient to inhibit physiological uptake in nonaffected myocardium. We have recently reported that a long fasting time (>18 h) is necessary for the precise evaluation of cardiac PET (6).
Endomyocardial biopsy (EMBx) is usually performed because the diagnosis of CS is based principally on histology. However, the diagnostic rate achieved with EMBx has been reported to range from 20% to 30% (7). The paper by Blankstein et al. (3) reports very interesting findings about EMBx from the right ventricle. The overall diagnostic rate was 27%, but among the 20 patients with abnormal perfusion and FDG uptake, 45% had positive findings. These results indicate that a positive PET finding is useful not only for predicting outcomes but also for determining the indications for performing an EMBx. Further study is needed to resolve the issue of whether a positive PET finding of myocardium can improve the diagnostic rate of EMBx.
- 2014 American College of Cardiology Foundation
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