Author + information
- Ron Blankstein, MD∗ (, )
- Michael T. Osborne, MD,
- Alfonso H. Waller, MD,
- Venkatesh L. Murthy, MD, PhD,
- Sharmila Dorbala, MD, MPH,
- William G. Stevenson, MD and
- Marcelo F. Di Carli, MD
- ↵∗Cardiovascular Division and Department of Radiology, Brigham and Women's Hospital, 75 Francis Street, Room Shapiro 5096, Boston, Massachusetts 02115
We thank Drs. Njeim, Bogun, and Crawford for their interest in our study (1). We agree that in the absence of histological confirmation of sarcoidosis, it is possible that there may be other chronic inflammatory processes that could have a similar presentation, hence, our designation in the title “suspected cardiac sarcoidosis.” Patients with this constellation of findings who lack a histological diagnosis are as common as those with a histological diagnosis and raise difficult management issues. We would note the following: 1) the vast majority of events in patients with abnormal positron emission tomography (PET) studies occurred in patients with known or a high likelihood of cardiac sarcoidosis (see the Online Appendix in our original paper ); 2) none of the patients in our study had known acute myocarditis (e.g., elevated cardiac enzymes), and although scar from prior episodes of myocarditis may cause arrhythmias, this would not result in increased FDG uptake; and 3) none of the patients with increased FDG had other potential alternative reasons for such findings such as coronary artery disease or any known systemic inflammatory or rheumatologic disease. Even in the absence of a histological diagnosis (which cannot always be obtained in cardiac sarcoidosis), abnormal PET findings were associated with a substantial increase in the rate of death/ventricular tachycardia.
The high event rate observed in our study is in part due to referral bias, because our center is a quaternary care center for advanced heart failure and arrhythmias. As expected, our study therefore included patients with a prior history of arrhythmias. It is also noteworthy that the high event rate observed in our study is in keeping with data from Schuller et al. (2), who reported that appropriate implantable cardioverter-defibrillator (ICD) therapies occurred in 36 (32%) of 112 patients with cardiac sarcoidosis over a mean of 29 months, and from Betensky et al. (3), who reported ICD therapies in 17 (38%) of 45 patients with cardiac sarcoidosis followed over a median of 2 years. In regard to events in patients with normal PET, we would point out that we used PET only to evaluate for inflammation or scar, and that it does not exclude nonischemic cardiomyopathy. In fact, all of the 6 patients with a normal PET scan who experienced events had systolic dysfunction. Therefore, if we were to define a “normal PET” as also having a normal left and right ventricular function, there would be zero events in this category.
In regard to the low prevalence of extracardiac sarcoidosis, it is important to note that we reported the frequency of extracardiac FDG uptake (which represents active inflammation) as distinguished from other radiological evidence of disease that may represent scar from inactive disease. However, even when accounting for the fact that patients without extracardiac FDG uptake may have had prior extracardiac sarcoidosis, we do believe that the presence of isolated cardiac sarcoidosis is underrecognized. In part, this is because prior clinical criteria, as well as most prior imaging studies, have only included patients with confirmed extracardiac disease. We believe that future criteria should address the fact that cardiac sarcoidosis can be present (and therefore should be diagnosed) even in patients without extracardiac disease. We also agree that a prospective study is needed to define the role of PET in selection of therapy for this challenging group of patients.
- American College of Cardiology Foundation