INRODUCTION
Sarcoidosis is a multisystem inflammatory disease characterized by the
presence of noncaseating granulomas of unknown aetiology. Although the
disease affects almost every organ system in the body, lung involvement
occurs in over 90% of all cases.1 The estimated
prevalence of sarcoidosis is 20-60 cases per 100,000 with worse outcomes
among African-American populations.1 There is lack of
data on the incidence and disease burden of sarcoidosis in Africa and
Ghana. Detailed clinical and epidemiological studies are urgently
required in this area.
Sarcoidosis has the worst prognosis when it involves the heart muscle.
Cardiac sarcoid (CS) is estimated to account for more than two-thirds of
global deaths in sarcoidosis patients.2,3 Heart muscle
involvement may be isolated (with no overt clinical manifestations of
systemic sarcoidosis masking early disease detection) or in association
with other systems involvement particularly pulmonary sarcoidosis. The
estimated prevalence of cardiac sarcoidosis (CS) is between 20 to 30%
in patients with sarcoidosis from autopsy studies as well as screening
of known sarcoidosis patients with cardiac magnetic resonance imaging
(MRI). However, only 5% of patients with systemic sarcoidosis have
clinical evidence of cardiac sarcoidosis.3–5 The
prevalence of isolated cases of CS is unclear although there are case
reports of such occurrence in the literature.6
Clinical presentation of CS is variable and can be benign and
asymptomatic or life-threatening with symptoms of heart failure, cardiac
arrhythmias or sudden cardiac death. Mitral valve regurgitation due to
papillary muscle dysfunction, pericardial involvement manifesting as
pericarditis or tamponade and pulmonary hypertension due to pulmonary
parenchyma injury or left ventricle (LV) dysfunction are all reported
manifestations of cardiac sarcoidosis. 3,7 CS has also
been identified incidentally after ECG abnormalities and cardiac
symptoms in patients with sarcoidosis, or unfortunately following sudden
death.3,6 Indeed up to 50% of deaths in sarcoidosis
may be related to cardiac involvement.8
The diagnosis of cardiac sarcoidosis however remains a challenge because
of non-specific symptoms and the absence of a single examination
technique to reliably diagnose the condition. Screening is however
imperative since treatment can significantly reduce the risk of sudden
death among affected patients.9 Expert opinion
recommend clinicians actively enquire about cardiac symptoms in
sarcoidosis patients at follow-up visits and have repeat ECGs every 6 to
12 months and particularly during tapering of corticosteroid treatment.
Detailed evaluation is warranted if clinical or ECG abnormalities are
detected.3,10
Several established diagnostic guidelines in existence are based on
expert consensus with none validated by prospective data or clinical
trials.11Clinicians must combine clinical
symptoms with advanced cardiac imaging techniques consistent with
sarcoidosis and demonstrate histological presence of noncaseating
granulomas, rule out alternative diagnosis and causes of noncaseating
granulomas before making a diagnosis of cardiac
sarcoidosis.4,12
The patchy distribution of noncaseating granulomas in myocardium
contributes to the low diagnostic yield (sensitivity of 10-25%) of
endomyocardial biopsy despite being the gold standard of
diagnosis.13 The invasiveness of the procedure and its
attendant complications contribute to the limited usefulness of
endomyocardial biopsy.14 CS may be accompanied by LV
dilatation as well as regional and global wall motion abnormalities.
Regional granulomatous inflammation can also lead to wall thinning and
akinesis. Cardiac magnetic resonance (CMR), currently the investigation
of choice can reliably identify all of these abnormalities by utilising
a combination of morphological and functional assessment tools that lead
to excellent sensitivity (96.9%) and specificity (100%) for detecting
cardiac sarcoidosis.3,15–17
Fluorodeoxyglucose – positron emission tomography (FDG-PET) scan is a
useful nuclear imaging modality that employs radioactive glucose to
detect areas of active inflammation with a sensitivity of 89% and
specificity of 78% in detecting cardiac sarcoidosis. FDG-PET scan has
the benefit of demonstrating both perfusion and metabolic activity
aiding in diagnostic specificity.18 However, FDG-PET
is even less accessible in settings such us ours.
The ECG is very useful in identifying conduction disorders, arrhythmias
or paroxysmal and intermittent rhythm disturbances in the case of Holter
ECG. However its sensitivity and specificity of diagnosing CS is low.
Echocardiography, although useful, cannot establish the diagnosis of CS
but its importance is seen in the assessment of associated complications
and monitoring of the course of the disease.16,18
The management of CS is multidisciplinary and involves cardiologists,
pulmonologists, radiologists, rheumatologists and others. The
pharmacological management of cardiac sarcoidosis involves the use of
immunosuppressive medications and cardiac-specific therapy to manage
cardiac sequelae of sarcoidosis. The goal of immunosuppressive therapy
is to reverse any ongoing active granulomatous myocarditis and
potentially prevent the progression of myocardial granulomatous
inflammation to scar tissue which leads to arrhythmias and ventricular
dysfunction.18 As the most frequent cause of death
from CS are heart rhythm disorders such as AV block and ventricular
arrhythmias, an irreplaceable role in the management of CS patients is
pacemakers and implantable cardiac defibrillators
(ICDs).19
Beyond these, general cardiology inputs in the management of the CS
patient may include guideline – directed medical management of systolic
and diastolic heart failure as with other aetiologies of heart failure.
The caveat however is use of beta blockers in the absence of pacemaker
because of frequent AV conduction abnormalities.20Antiarrhythmic agents including amiodarone may be used to maintain
normal sinus rhythm in patients with atrial arrhythmias or symptomatic
ventricular tachycardia.20
Cardiac specific treatment typically occurs in combination with
immunosuppressants since they have no impact on the ongoing pathological
process of sarcoidosis.3 Systemic corticosteroids are
the cornerstone of the treatment in CS and are considered first-line
agents because their efficacy and attainment of significant response in
a relatively short period. Other immunosuppressive drugs such as
methotrexate, azathioprine, mycophenolate mofetil, leflunomide,
cyclosporine, or cyclophosphamide can be used in the event of
corticosteroids failure, development of adverse side effects with
corticosteroid therapy, prevention of corticosteroid adverse side
effects in patients requiring higher doses (> 10mg/day
prednisolone) of corticosteroids as maintenance therapy and in
combination therapy.3,20,21
We present two cases of cardiac sarcoidosis with differing clinical
presentations.