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.