Several studies have attempted to evaluate the role of immunosuppression for reducing VA in patients with cardiac sarcoidosis, but results have been inconsistent.S7.6-14 S7.6-16 Furthermore, a worsening of VA has been reported with immunosuppressive therapy (usually glucocorti- coids) in a number of patients, including electri- cal storm developing in some within 12 months of initiating therapy.S7.6-15 One study reported a decrease of arrhythmia burden with steroid ther- apy but only when given in the early stages of the disease; those with advanced LV dysfunction did not experience benefit.S7.6-16 A systematic combined treatment approach was successful in 63% of patient in a series in which medical ther- apy included both steroids and antiarrhythmic medications, followed by radiofrequency cath- eter ablation if needed.S7.6-14 Immunosuppressive therapy may serve a dual purpose beyond arrhythmia effects as it may help stabilize dis- ease progression and prevent further deteriora- tion of LV function, although this has yet to be demonstrated in RCTs. Steroids do not appear to reverse advanced ventricular dysfunction once present, which supports the importance of early diagnosis and intervention.S7.6-1 PET scanning for assessing inflammation and scar is being increas- ingly used in sarcoidosis as well, but data sup- porting its use for guiding therapy of arrhythmias are limited. 7.6.1. Other Infiltrative Cardiomyopathies Infiltrative cardiomyopathies are a heterogeneous group of uncommon systemic diseases with associat- ed cardiac involvement. In some infiltrative cardiomy- opathies, such as Fabry s disease, VAs are uncommon. Some, such as hemochromatosis, are highly treatable especially when diagnosed early. In all cases, treat- ment of the underlying condition must accompany management of cardiac arrhythmias. Most studies of infiltrative cardiomyopathies and arrhythmias are small and observationalS7.6.1-1 but, in general, unless contraindications are present, VAs should be treated as in any other cardiomyopathy. See Section 7.6 for sarcoidosis. 