HISTORY, CURRENT ILLNESS AND PHYSICAL EXAMINATION
85-year-old man, with fasting hyperglycaemia as the only history of interest. Active and independent. He had been admitted a year earlier to the geriatric ward for a first episode of heart failure in the context of lower respiratory tract infection.
Clinical evolution was favourable with diuretics and empirical antibiotic therapy. Although he was in sinus rhythm on admission, shortly afterwards he developed atrial fibrillation with slightly elevated ventricular response. An echocardiogram (ECG) was performed with findings of severe ventricular hypertrophy, biauricular dilatation and restrictive diastolic pattern, compatible with infiltrative myocardial disease. He was discharged six days later with acenocoumarol, torasemide 20 mg and bisoprolol 2.5 mg, pending completion of the outpatient study.

COMPLEMENTARY TESTS
ECG: atrial fibrillation with mean ventricular response of 60 bpm, low voltage in limb leads and pseudoinfarction pattern with QS in V1-V2.
ANALYTICS: amino-terminal pro-brain natriuretic peptide (NT-proBNP) fraction: 4,175 pg/ml, ultra-sensitive troponin T: 65 ng/l. The rest was normal, including haemogram, glycaemia, renal function, liver function, thyroid hormones, ions, lipids and iron study. The protein study was normal, with proteinogram, serum/urine immunofixation and light chains.
Control echocardiogram: non-dilated left ventricle, with severe concentric hypertrophy of granular pattern, maximum thickness of the basal septum 28 mm, left ventricular ejection fraction (LVEF) 45-50%. Severe diastolic dysfunction with restrictive pattern and estimated pulmonary capillary pressure of 30 mmHg. Moderate biauricular dilatation.
Hypertrophic right ventricle. Thickened mitral valve, with mild insufficiency. Estimated systolic pulmonary pressure 43 mmHg. Mild pericardial effusion.
ABDOMINAL ECOGRAPHY: mild hepatomegaly, without other pathological findings.
HOLTER ECG: atrial fibrillation with an average heart rate (HR) of 65 bpm. Minimum HR of 35 bpm during nocturnal rest and maximum of 120 bpm during physical exercise.
Nonsignificant pauses predominantly at night (the longest lasting 2 seconds).
Isolated ventricular extrasystoles, infrequent.
Abdominal fat and salivary gland biopsies: negative for amyloid material.
CARDIAC MRI: left ventricle with marked diffuse concentric thickening, mild systolic dysfunction. Mild dilatation of both atria.
Diffuse parietal late enhancement in all four chambers. Mild pleural effusion, no pericardial effusion.
GRAMMAGRAPHY technetium-diphostat (99mTc-DPD): intense biventricular tracer uptake, grade 2.
GENETIC STUDY by Sanger sequencing of the TTR gene: negative.

CLINICAL EVOLUTION
During follow-up, the patient has remained stable, with no new admissions or visits to the emergency room for heart failure. He currently reports dyspnoea on moderate exertion, asthenia, two-pillow orthopnoea and mild malleolar oedema, predominantly in the evening. Blood pressure is usually low and there are episodes of non-syncopal dizziness with orthostatic features.
In terms of treatment, acenocoumarol has been replaced by a direct-acting anticoagulant due to poor control of the international normalised ratio (INR), with time in therapeutic range below 30%. Bisoprolol has been withdrawn due to relatively slow heart rate (50-60 bpm) and hypotension (90/60 mmHg). Current medical treatment is rivaroxaban 15 mg, torasemide 10 mg and spironolactone 25 mg, with a flexible diuretic regimen.

DIAGNOSIS
Congestive heart failure with mildly depressed ejection fraction, New York Heart Association (NYHA) functional class II.
Restrictive cardiomyopathy due to TTR-wild type amyloidosis, with severe biventricular hypertrophy and severe diastolic dysfunction.
Permanent atrial fibrillation, with controlled ventricular response. High cardioembolic risk, anticoagulated.
