144 Although recent cardiac sarcoidosis guidelines emphasize FDG PET/CT and CMR for diagnosing myocardial involvement, they also recognize the importance of addressing unexplained functional symptoms. SCAD may contribute to cardiac arrhythmias, while granulomatous inflammation within the heart can also directly lead to cardiac arrhythmias. In this context, [123I]MIBG scintigraphy’s potential utility lies in bridging the gap when autonomic dysfunction is suspected.25,26 Cardiac sympathetic activity is vital for heart function, and [123I]MIBG scintigraphy non-invasively evaluates sympathetic terminal integrity, detecting dysfunction associated with worse prognosis in various cardiac diseases.25 [123I]MIBG scintigraphy has demonstrated the capability to detect disruptions in the adrenergic nervous system among patients with sarcoidosis, often exhibiting greater sensitivity compared to thallium scintigraphy.27 Additionally, reduced [123I]MIBG uptake was identified as a predictor of fatal arrhythmias, highlighting its potential utility in risk stratification for interventions such as implantable cardioverter-defibrillator (ICD) therapy.28 Treatment with carvedilol demonstrated beneficial effects in SCAD, particularly in heart failure and autonomic disorders, by mitigating sympathetic overactivity.19 Case reports have described sarcoidosis patients with severe SCAD who showed improvement after carvedilol treatment.13,19 This study offers a preliminary but promising indication of carvedilol’s effectiveness in alleviating symptoms of SCAD among patients exhibiting abnormalities on [123I]MIBG scintigraphy. Of the cohort, 80% commenced carvedilol treatment, with 88% reporting symptomatic improvement, although 50% experienced adverse effects such as dizziness, fatigue, and nausea. However, given the small sample size and the retrospective nature of the study design, larger prospective studies are necessary to comprehensively evaluate the efficacy and safety of carvedilol in this patient population. The retrospective nature of this study represents a significant limitation, as it restricts the ability to draw causal inferences and introduces the potential for selection bias. Autonomic dysfunction was evaluated exclusively through symptoms and [123I]MIBG scintigraphy, which, while valuable, may not comprehensively represent the complex nature of autonomic impairment. Additional assessments, such as heart rate variability analyses or other functional tests, were not incorporated, thereby limiting the depth of the evaluation. Furthermore, the small sample size reduces both generalizability and statistical power of the findings. Larger, prospective studies are necessary to confirm these results and to elucidate the broader clinical implications of [123I]MIBG scintigraphy in sarcoidosis. Although [123I]MIBG scintigraphy demonstrates potential for diagnosing and risk stratifying SCAD, it has not yet been incorporated into standard diagnostic guidelines. Consequently, its application in routine clinical practice remains limited. A significant barrier to broader adoption is the restricted availability of [123I]MIBG scintigraphy, which is currently accessible only in specialized centers. This limitation impedes widespread clinical use and the generation of large-scale data essential for its inclusion in diagnostic protocols. Standardization and validation of [123I]MIBG scintigraphy, supported by large-scale studies incorporating complementary functional assessments, are imperative for its integration into clinical practice. Such efforts would improve patient outcomes, optimize healthcare resource utilization, and address the need for further research and guideline development, ultimately facilitating wider adoption.25 9 150 9
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