Page 8 - BH-2-4

Brain & Heart Cardiac sarcoidosis with AVB and VA

with AVB and VA elevating the risk of sudden cardiac (GCM), both of which were associated with a high risk of
death. Most deaths from CS result from arrhythmias. CS adverse cardiac events. 12
is a heterogeneous disease, displaying varying severity and Diagnostic criteria for CS vary among expert societies.
presentation across ethnicities. Prognosis is particularly Key criteria and differences are detailed in Table 1, based
poorer in Japanese patients than in those from Europe or on guidance from the Japanese Circulation Society (JCS,
the United States (US), with studies on Japanese patients 2016), the World Association for Sarcoidosis and Other
13
often showing worse outcomes. This ethnic variation is Granulomatous Disorders (WASOG, 2014), and the
3
14
also observed in African American and White patients. Heart Rhythm Society (HRS, 2014), Notably, the JCS
15
A large-scale US study revealed a higher incidence of VAs criteria are unique in not requiring positive histology for
and AVB in White patients than in African American a definitive diagnosis. Common points among the criteria
patients but showed worse overall outcomes, including include advanced AVB and unexplained sustained VT,
cardiogenic shock and mortality, in African Americans and the inclusion of extracardiac disease emphasizes the
than in Whites. 4 need for a multi-specialty evaluation when CS is suspected.
2. Review However, the differences in diagnostic criteria lead to
varied CS cohorts across different countries and centers,
2.1. Presentations of CS complicating the comparison of results, treatments, and

CS can present in various forms, making diagnosis difficult. outcomes due to a lack of standardization.
Autopsy data have revealed a high mortality rate associated 2.2. Pathophysiology of AVB and VA in CS
with CS, with many cases remaining undiagnosed during
the patient’s lifetime. In fact, sudden cardiac death Although the exact cause of sarcoidosis remains
5
(occurring within 24 h of symptom onset which often unknown, the disease is characterized by the formation
results in death at the scene or post-resuscitation without of granulomas in various tissues. Granulomas are clusters
neurological recovery) may be the sole presentation in up of cells surrounded by lymphocytes and plasma cells,
to 14% of cases, as observed in a large-scale Finnish study. including macrophages and often multinucleated giant
6
However, most patients with asymptomatic CS, diagnosed cells, along with infiltrating T and B cells. 16,17 Granulomas
through cardiac magnetic resonance (CMR) imaging, have are not unique to sarcoidosis; they can also occur in
been reported to follow a benign clinical course. 7 conditions such as giant cell arteritis, Crohn’s disease, and
granulomatosis with polyangiitis. They typically form in
CS may present as VAs, heart failure, or AVB, response to foreign bodies or specific infections such as
with heart failure increasing the risk of arrhythmia tuberculosis. 17
and hospitalizations. The disease burden is high,
8
with sarcoidosis posing a greater risk of heart failure In CS, the myocardium is the most clinically significant
development than known factors such as hypertension and site for granuloma formation, leading to inflammation
coronary artery disease. CS is also an important differential and the development of non-conductive scar tissue. This
9
diagnosis for patients presenting with otherwise idiopathic results in the formation of re-entry circuits around the
18
ventricular tachycardia (VT). A case series showed that scarred areas. However, it remains controversial whether
12% of patients who underwent ablation for idiopathic active inflammation or subsequent scarring and fibrosis
VT were later diagnosed with arrhythmogenic CS, often primarily induces the development of VAs. Granulomas
17
10
in a delayed manner. These patients were relatively are formed in various locations, resulting in a wide range
19
young (average age: 51 years). Although two-thirds of the of VAs with different morphologies. Conversely, AVBs
patients had extracardiac sarcoidosis at diagnosis, it was typically occur when there is substantial involvement of
asymptomatic in all but two cases, as determined through the septum, impacting the His-Purkinje system. 20
18F-fluorodeoxyglucose positron emission tomography
(18F-FDG PET). The remaining one-third of the patients 2.3. Distinguishing features of CS from other
had isolated cardiac involvement. Similarly, a prospective conditions presenting with AVB and VAs
study showed that 34% of patients with AVB of unknown Although echocardiography has a low sensitivity for
origin were later diagnosed with CS. Compared with diagnosing CS, thinning of the basal interventricular
11
patients with idiopathic AVB, those with CS-related AVB septum and/or regional wall motion abnormalities in a non-
and aged <60 years had more adverse cardiac events coronary distribution in patients with known extracardiac
(0/21 vs. 3/11, p = 0.011). Likewise, Kandolin et al. found sarcoidosis is suggestive of cardiac involvement.
11
that over 25% of unexplained AVB cases in young and Echocardiography can also provide cardiac function data
middle-aged adults were due to CS or giant cell myocarditis that help determine the need for device implantation.

Volume 2 Issue 4 (2024) 2 doi: 10.36922/bh.3515