Basic Science
Importance of Visualizing Heart Failure With Nuclear Medicine Techniques
2021 Volume 85 Issue 11 Pages 2109-2110
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2021 Volume 85 Issue 11 Pages 2109-2110
Heart failure (HF) has become an important topic for Japan in a society with many elderly patients. HF is characterized by a high proportion of cardiomyopathy in younger patients, whereas the proportion of ischemic heart disease increases as the population ages. Therefore, the most important factor in the treatment of HF in the middle group of patients is to know the underlying disease.
Article p 2102
Visualization of the pathogenesis and cause of HF can help patients understand their own condition, plus a better understanding of the patient’s disease can lead to a more positive attitude toward treatment, which in turn may improve the efficacy of treatment.
Nuclear cardiology is more adept at assessing myocardial function than morphological abnormalities. Relative ischemia can be assessed using 99 mTc agents (sestamibi or tetrofosmin) or thallium chloride to identify areas of maximal myocardial ischemia (Table).1 Flow reserve can also be assessed by measuring absolute blood flow using ammonia positron emission tomography (PET) techniques.2 Recently, it has become possible to evaluate blood flow using PET techniques with 83Rb. The metabolic status of the myocardium evaluated by fatty acid metabolism using 123I-BMIPP, and glucose metabolism using 18F-FDG PET can be used to evaluate cardiomyopathy and potential myocardial ischemia.3,4 In addition, evaluation of cardiac sympathetic nerves by 123I-MIBG supplies useful information for prognostic evaluation of HF patients.5 Cardiac nuclear imaging also plays an important role in the diagnosis of secondary cardiomyopathy, such as 99 mTc-PYP and 99 mTc-MDP,6,7 which are important in the diagnosis of ATTR cardiac amyloidosis, and 18F-FDG-PET, which can be used to evaluate the activity of cardiac sarcoidosis.8 Triglyceride deposit cardiomyovasculopathy is a newly identified, refractory cardiovascular disease for which abnormal washout of BMIPP is a diagnostic criterion.9 All these tests have the advantage of collecting patient information noninvasively.
| Target | Tracer | Clinical goal |
|---|---|---|
| Perfusion (ischemia) | SPECT (201Tl, 99mTc-sestamibi, 99mTc-tetrofosmin) | Identify ischemia, indication for revascularization |
| PET (13NH3, 82Rb, 18F-flupiridaz) | ||
| Absolute flow (flow reserve) | PET (15H2O, 13NH3, 82Rb, 18F-flupiridaz) | Identify global disease burden |
| Viability | SPECT (201Tl, 99mTc-sestamibi, 99mTc-tetrofosmin) | Evaluate revascularization benefit |
| PET (18F-FDG) | ||
| Sympathetic innervation | SPECT (123I-MIBG) | Risk assessment, guide anti-arrhythmic therapy |
| Metabolism | SPECT (123I-BMIPP) | Evaluate jeopardized myocardium |
| PET (18F-FDG) | Diagnosis of TGCV | |
| Inflammation | SPECT (111In-/ 99mTc-WBCs) | Diagnose cardiac sarcoidosis |
| PET (18F-FDG) | ||
| Amyloid deposit | SPECT (99mTc-PYP, 99mTc-MDP) | Determine cardiac involvement |
| PET (11C-PIB, 18F-amyloid markers) | ||
| Sigma-1 receptor | SPECT (125I-OI5V) | Determine myocardial injury (ischemia, hypertrophy) |
BMIPP, β-methyl-P-iodophenyl-pentadecanoic acid; FDG, fluorodeoxyglucose; MIBG, metaiodobenzylguanidine; MDP, methylene diphosphonate; PET, positron emission tomography; PYP, pyrophosphate; TGCV, triglyceride deposit cardiomyovasculopathy.
It is important to use these cardiac nuclear imaging techniques for appropriate HF management. In particular, early identification of secondary cardiomyopathy is important in determining the treatment strategy, but invasive procedures for aggressive pathological diagnosis are often difficult to perform. Noninvasive diagnosis before HF becomes manifest is clinically useful, and we must reconsider the value of cardiac nuclear imaging for noninvasive diagnosis.
In this issue of the Journal, Wakabayashi et al10 present a remarkable report on the visualization of sigma-1 receptors expressed in the myocardium using iodine-labeled OI5V. Clinical application of this radionuclide agent is expected to enable early visualization and evaluation of cardiomyopathy, not only in ischemic but also in hypertrophic cardiomyopathy. I would like to emphasize again the importance of visualizing HF to help patients understand their condition and cooperate with treatment. In the clinical setting, this is of great importance. In addition, of particular note in this study is that OI5V is an iodine-labeled agent. I-123 has a half-life of 13.2 h and does not emit β rays, which means that the exposure radiation dose is low. It also has the advantage that the energy range of gamma rays is very efficient for SPECT imaging, and as a result, it has potential for widespread clinical use.
None declared.
