CARDIOVASCULAR JOURNAL OF AFRICA • Volume 35, No 3, September – October 2024 AFRICA 187 Discussion Although the wild-type of ATTR-CM is the most commonly reported type of ATTR-CM, the precise incidence and prevalence in different geographic regions is unknown.7 Existing patient registries however suggest that the disease is predominantly found in elderly male Caucasians above the age of 80 years.7 Among patients with ATTRv-CM in the United States, the most common mutation, Val122Ile (pV142I), appears to be exclusive to individuals of West African descent.7 The disease phenotype is strikingly similar to ATTRwt-CM, with symptom onset around the age of 69 years.7 ATTRwt-CM is largely a disease of elderlymales.4 Historically, octogenarians have been frequently affected with a more dismal prognosis due to age-related co-morbidities, as seen in this case.8,9 Females and younger patients can however also be affected.4,10 In a study by Grogan et al., the youngest affected patient was 47 years, challenging the notion that ATTRwt-CM is solely a disease of the elderly.4 A few decades ago, ATTRwt-CM was more commonly identified at post mortem due to the insidious disease course and resultant ante-mortem diagnostic delays.4,6 Over 60% of patients present with symptoms of heart failure at diagnosis, as was the case in our patient.10 In low-resource settings, the ECGcan provide initial diagnostic clues. Discordance between QRS voltages and the degree of LVH may be observed, as seen in our patient.3 However, low-voltage QRS complexes are a relatively late finding, with low sensitivity, found in only about 30% of patients with cardiac amyloid.3,11 Atrial fibrillation/flutter and conduction abnormalities are common,10 with atrial arrhythmias reported as a presenting feature in approximately two-thirds of patients, as seen in our patient.4,10 Atrial arrhythmias result from atrial remodelling, caused by amyloid infiltration of atrial tissue and concomitant dilatation of the atrium. Nearly half of these patients develop carpal tunnel syndrome, often bilateral, five to 10 years before a diagnosis of ATTRwt-CM is made.6,10 In this case, the diagnosis of carpal tunnel syndrome preceded the onset of symptoms by four years. Tenosynovial tissue biopsy at the time of carpal tunnel release surgery may facilitate an early diagnosis,12 however we found no record of a prior histopathological diagnosis in our patient. Sood et al. observed a low diagnostic yield with tenosynovial tissue biopsy; a cumulative incidence of 0.55% of amyloidosis at 10 years in patients undergoing carpal tunnel release surgery.12 Although the pathology is predominantly cardiac, other organs may be involved, although less frequently.10 Our patient probably had infiltration of the liver, pleura and prostate on account of the presence of cholestatic hepatic injury, bilateral pleural effusion and prostamegaly, respectively. Although the clinical course of patients with ATTRwt-CM is fairly distinctive, as described in our patient, it is important to rule out AL amyloidosis and familial ATTR amyloidosis for a tailored therapeutic approach. Notably, patients with Table 1. Laboratory investigation results Variables Baseline Repeat Reference range Full blood count Haemoglobin, g/dl 11.8 11.0–18.0 Platelet count, 109 cells/l 134.0 150.0–450.0 Total white cell count, 109 cells/l 7.8 2.5–8.5 Renal function Sodium, mmol/l 134.0 130.0 135.0–150.0 Potassium, mmol/l 5.0 5.2 3.5–5.5 Chloride, mmol/l 97.0 99.0 95.0–110.0 Urea, mmol/l 14.5 15.3 2.0–7.0 Creatinine, µmol/l 124.0 120.0 71.0–133.0 eGFR (ml/min/1.73 m2) 63.0 65.0 > 89.0 Liver function test Total bilirubin, µmol/l 49.4 Direct bilirubin, µmol/l 33.3 0.0–5.0 Aspartate transaminase, U/l 33.0 15.0–46.0 Alanine transaminase, U/l 19.0 13.0–69.0 Alkaline phosphatase, U/l 259.0 38.0–129.0 Gamma glutamyl transferase, U/l 194.0 12.0–58.0 Total protein, g/dl 70.0 63.0–82.0 Albumin, g/dl 32.0 35.0–50.0 Lipid profile Total cholesterol, mmol/l 3.10 3.30–6.20 LDL cholesterol, mmol/l 2.01 0.00–3.90 HDL cholesterol, mmol/l 0.57 1.03–1.55 Triglycerides, mmol/l 1.26 0.40–2.25 eGFR: estimated glomerular filtration rate, LDL: low-density lipoprotein, HDL: high-density lipoprotein. Fig. 4. Cardiac MRI showing hypertrophy of the walls of both ventricles (A). Diffuse pattern of late gadolinium enhancement throughout the myocardium with a failure to null in look-locker sequences (B) with positive T1 values (C). A B C
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