HISTORY, CURRENT ILLNESS AND PHYSICAL EXAMINATION

History
Male, 73 years of age, his medical history includes: No known ADRs. Cardiovascular risk factors (CVRF): hypertension with poor control and dyslipidaemia. Severe aortic stenosis with valve replacement with a biological prosthesis in 2016. Chronic ischaemic heart disease: moderate lesion of 40-50% in non-revascularised anterior descending artery. Surgical interventions: aortic valve replacement, shoulder arthroplasty, tonsillectomy, inguinal herniorrhaphy.
Usual treatment: acetylsalicylic acid 100 mg, atorvastatin 80 mg, amlodipine 5 mg, bisoprolol 2.5 mg, imidapril 10 mg.   Present illness The patient came to the emergency department of our hospital 7-10 days ago, complaining of fatigue, dyspnoea and a feeling of dizziness with light to moderate exertion, which had been triggered by a previous episode of severe stabbing chest pain. For the last 3 months he has been experiencing intermittent chest pain, for which reason he has been seen at the cardiology outpatient clinic. A stress test was requested, with negative results for ischaemia, and a stress cardiac magnetic resonance imaging (CMR) is pending.

Physical examination
Blood pressure (BP) 170/90 mmHg, heart rate (HR) 60 bpm. Oxygen saturation 95% (FiO2 0.21). Cardiac auscultation: regular heart sounds, aortic systolic murmur II/VI. Pulmonary auscultation: preserved vesicular murmur without pathological sounds. Abdomen: soft and depressible, without signs of defence, masses or visceromegaly. No peripheral oedema. Pulses symmetrical and normal.

COMPLEMENTARY TESTS
ECG: sinus rhythm at 60 bpm. First degree atrioventricular block (AVB) (PR 480 ms). Narrow QRS with axis at 0o in frontal plane. No pathological alterations in repolarisation. Laboratory tests during admission: glucose 111 mg/dl, urea 35 mg/dl, creatinine 0.87 mg/dl, sodium 144 mmol/l, potassium 4.5 mmol/l, uric acid 4.4 mg/dl, cholesterol 151 mg/dl, calculated LDL 102 mg/dl, HDL 38 mg/dl, triglycerides 104 mg/dl, total bilirubin 0,76 mg/dl, GPT 27 U/l, GOT 32 U/l, GGT 19 U/l, alkaline phosphatases 74 mU/ml, haemoglobin 14.4 g/dl, haematocrit 44%, MCV 93 fl, leucocytes 7900, platelets 201000, NT-proBNP 296 pg/ml, CRP 14.1 mg/l, procalcitonin 0.05 ng/ml. Chest X-ray: normal cardiac silhouette, no signs of heart failure. Transthoracic echocardiogram: left ventricle of normal dimensions with moderate hypertrophy of its walls (IVT 15 mm). Preserved global systolic function (LVEF 65%) without segmental alterations of contractility at rest. Ventricular filling wave fusion with normal E/e" ratio. Slightly dilated left atrium. Biological prosthesis in normofunctioning aortic position (maximum gradient 35 mmHg, mean gradient 18 mmHg), without regurgitation. Mitral valve with normal opening and minimal valvular insufficiency. Right ventricle of normal dimensions with borderline function by longitudinal parameters (TAPSE 16 mm, tricuspid s" 9.5 cm/s) after cardiac surgery. Absence of tricuspid insufficiency. Normal inferior vena cava (16 mm) with inspiratory collapse > 50%. Absence of pericardial effusion. Continuous renal venous flow. Exercise test: maximal exercise test, negative for ischaemia, stopped in stage 3 of Bruce protocol due to muscle exhaustion. Work achieved 11 METs. AV conduction 1:1 throughout the test. Good chronotropic and tension response. Functional capacity adequate for his age. Stress CMR: left ventricle with increased septal thickness predominantly (17 mm) and preserved mass (71 g/m2), normal MPR (1.18). Volumes (IVTDVI 60 ml/m2; IVTSVI 17 ml/m2) and segmental and global systolic function within normal (LVEF 72%). Right ventricular volumes (IVTDDI 56 ml/m2; IVTSVD 19 ml/m2) and systolic function within normal (RVEF 66%). Atria of normal size. Biological valve prosthesis in aortic position. Peak systolic velocity of 3.5 m/s. Periprosthetic collection surrounding the valve annulus and contrast uptake in relation to surgery. Slight dilatation of root (37 mm, 20 mm/m2) and tubular portion (38 mm, 20 mm/m2). Rest of thoracic aorta of preserved calibre. Provocation of ischaemia with i.v. Regadenoson (400 mcg i.v., well tolerated) negative. Baseline: 58 bpm and 135/85 mmHg. Stress: 82 bpm and 122/77 mmHg. Baseline ECG: PR of 0.480 s, without complications during regadenoson stress. Gadoteric acid is administered i.v. at 0.15 mmol/kg without complications. Absence of myocardial fibrosis or necrosis. Only contrast uptake in periprosthetic collection. In summary, absence of inducible ischaemia. Biological aortic valve prosthesis with contrast-enhancing periprosthetic collection of uncertain significance.
PET-CT: biological aortic prosthesis with intense hypermetabolism (SULmax 6.6 g/ml, late 9.07 g/ml) accompanied by mural thickening of the ascending aorta, suggestive of endocarditis due to prosthetic infection. Hypermetabolic right upper and lower right paratracheal (SULmax 2.8 g/ml), subcarinal and bilateral hilar (SULmax 3.7 g/ml) contrast-enhancing hypermetabolic adenopathies suggestive of an infectious process secondary to endocarditis. Absence of metabolic activity in cephalic lymph node stations or bone marrow. Physiological glandular and encephalic uptake. Absence of pathological metabolic activity in cervical or axillary ganglion stations. Subsegmental hypermetabolic atelectasis of the upper segment of the lower lobe of the right lung. No pleural or pericardial or pleural effusion. Sternal sternotomy band with physiological hypermetabolism. Hepatic, splenic, pancreatic, renal and adrenal parenchyma without significant metabolic alterations. Small bowel loops with diffuse metabolic activity, with no significant pathological accumulations of activity. Absence of metabolic activity in abdominal, retroperitoneal, pelvic and inguinal lymph node stations. No free abdominal fluid. Circumferential mural thrombosis in the abdominal aorta with partial obstruction of the right common iliac artery with diffuse atheromatosis. No evidence of significant morphological or metabolic alteration in the bone framework. Conclusions: focus of hypermetabolism in aortic valve prosthesis suggestive of endocarditis, with reactive mediastinal and pulmonary adenopathies. Circumferential mural thrombosis of the abdominal aorta and partial obstruction of the right common iliac artery.

CLINICAL COURSE
In the case of a patient with a conduction disorder presenting with exertional dyspnoea and dizziness, it was decided to admit him to cardiology to complete the study. A new exercise stress test was requested to assess the reaction to exercise, and an adequate chronotropic response and 1:1 conduction was observed throughout the test. A transthoracic echocardiogram was performed, which ruled out prosthetic dysfunction, without observing segmental contractility alterations suggestive of ischaemia. After the absence of relevant findings in the examinations performed, it was decided to discharge the patient from hospital with withdrawal of beta-blockers. Given the persistence of atypical chest pain with a history of previous coronary artery disease, stress CMR was brought forward with outpatient monitoring in cardiology outpatient clinics. The following week a stress CMR was performed, with negative results for ischaemia, but a periprosthetic collection with contrast uptake was found, of uncertain significance, which could correspond to postoperative inflammatory activity or an infectious process. On assessing the results, taking into account the remoteness of the intervention (> 3 years) and given the possibility of infective prosthetic endocarditis, it was decided to readmit the patient to cardiology to complete the study and start antibiotic treatment. Empirical treatment with ampicillin, cloxacillin and gentamicin was started in agreement with the infectious diseases unit. Blood cultures and serology for endocarditis were requested, with negative results. It was decided to complete the imaging study with PET-CT, which showed the presence of hypermetabolism in the aortic valve prosthesis suggestive of endocarditis, with reactive mediastinal and pulmonary adenopathies; as an incidental finding, a circumferential mural thrombosis of the abdominal aorta and partial obstruction of the right common iliac artery were found. With the above findings, the case was discussed in a joint medical-surgical session between cardiology, cardiac surgery and the infectious diseases unit. Since the patient was stable, with no evidence of prosthetic dysfunction or acute complications, initial antibiotic treatment was chosen for 6 weeks, changing the previous regimen to daptomycin, ceftriaxone and doxycycline, with subsequent re-evaluation. After the first 10 days of treatment, the patient remained clinically stable, and it was decided to discharge him to the home hospitalisation unit (HHU) to complete the antibiotic regimen. Also, with a history of coronary heart disease and the finding of peripheral arterial disease with mural thrombosis of the abdominal aorta, lipid-lowering treatment was intensified with the addition of a combination of atorvastatin/ezetimibe. After 6 weeks of antibiotic therapy, a new control PET-CT scan was performed, in which periprosthetic hypermetabolism persisted but of less intensity than previously, with disappearance of the reactive adenopathies. With the good response to treatment, it was decided to complete 4 more weeks of antibiotic treatment, replacing doxycycline with rifampicin, which would subsequently be maintained in monotherapy until completing 6 months of treatment.

DIAGNOSIS
Late infective endocarditis on biological aortic prosthesis.
First-degree atrioventricular block (AVB) secondary to aortic endocarditis.
Circumferential mural thrombosis of the abdominal aorta.
