Personal history
The patient is a 53-year-old male, with no drug allergies. Type 2 diabetes mellitus of 3 years of evolution, treated with oral antidiabetics with good control, without other classic cardiovascular risk factors. Depressive syndrome under pharmacological treatment

In August 2014 (4 months prior to admission to the emergency department) he underwent an outpatient study in Internal Medicine due to asthenia, anorexia and weight loss with splenomegaly and Raynaud's, positive ANAs 1/640 with homogeneous nucleolar pattern and positive aniScl 70; a diagnosis of systemic sclerosis was established and immunosuppressant treatment, haemorrheological treatment and calcium antagonists were started.

The patient continues chronic treatment with methotrexate 15 mg every 24 hours, pentoxifylline 400 mg every 24 hours, diltiazem 60 mg every 8 hours, calcium folinate 15 mg every 24 hours, omeprazole 20 mg every 24 hours, glimepiride 2 mg every 24 hours and desvenlafaxine 50 mg every 24 hours.

Current illness
48 hours prior to his arrival at the ED, the patient reported marked asthenia and dyspnoea on minimal exertion, for which he discontinued diltiazem on the recommendation of his primary care physician. Despite this, his symptoms persisted and his dyspnoea even worsened the following morning, so his family called 112 and he was attended at home by the SAMU who performed an electrocardiogram (ECG) which revealed complete atrioventricular block (AVB) with wide QRS escape at 30x ́, deciding on superficial sedation, implantation of a transcutaneous pacemaker and transfer to the Emergency Department of our centre.

He denied any other symptoms of heart failure, fever or other symptoms of interest. On arrival at the ED, a new ECG showed complete AVB with wide QRS leakage alternating with transcutaneous MCP rhythm in command mode with no capture failures, and on telemetry, asymptomatic, self-limited bouts of polymorphic ventricular tachycardia of the torsades de pointes type. Urgent admission to the Coronary Unit was decided.

Physical examination in the emergency department
Blood pressure: 170/90 mmHg.
Heart rate 65 beats per minute with transcutaneous MCP.
To 36.2 °C.
Sat O2 96% with oxygen goggles at 2 litres per minute.
Dark complexion, microstomia, sclerodermic skin on trunk and hands, no telangiectasias, no ulcers, no calcinosis lesions, no tendon rubbing. Complete normal neurological examination. No jugular ingurgitation.
Carotid auscultation: no murmurs
cardiac auscultation: rhythmic heart sounds without murmurs. Pulmonary auscultation: bilateral dry crackles predominantly in the basal and lateral areas.
Abdomen: soft, depressible, non-painful, with palpable splenomegaly. Upper limbs: symmetrical peripheral pulses.
Lower limbs: no oedema or signs of deep vein thrombosis, with symmetrical pulses.

COMPLEMENTARY TESTS
During admission: Biochemistry: basal glycaemia 95 mg/dL, urea 55 --> 76 --> 128 --> 160 --> 159 --> 212 --> 212 mg/dL; creatinine 1.97 --> 2.36 --> 3.7 --> 4.52 --> 5.16 --> 7.08 mg/dL; estimated glomerular filtration rate 30 --> 25 --> 21--> 14 --> 12 --> 8 mL/min; sodium ion 132 mmol/L; potassium ion 4.1 mmol/L; creatine kinase 160 --> 140 --> 182 U/L; troponin T 320 --> 370 --> 486 ng/L (cut-off point: 35 ng/L); NT ProBNP 70000; liver function tests normal; albumin 33 g/l; total cholesterol 145 mg/dL; LDL 89; HDL 29; TAG 132; HbA1c 6.5. Thyroid hormones normal. Arterial blood gases: (on admission) pH 7.48, pO2 64 PCO2 33, HCO3 25. (During the episode of APE) pH 7.30, pO2 55, PCO2 48, HCO3 25. (24 hours after APE) pH 7.40, pO2 67 PCO2 35, HCO3 29. CBC: Hb 12.6 --> 11.5 --> 10 --> 12 g/dl (elevated RDW), leukocytes 10970 --> 17240 --> 12300 --> 9430/μl and plaq 293 --> 230 --> 145 --> 130 --> 130/μl.

Coagulation study:
PT 96%, TTPA 34.5 sec, fibrinogen 530 mg/d. Immunoglobulins: Ig G: 17,94, Ig A: 2,86, Ig M: 3,46, C3: 0,79, C4: 0,18. Autoimmunity: ANA: positive 1/640, homogeneous nucleolar pattern. Anti MPO, Anti MBG, ANCA: negative. ENAS: positive. Positive: anti-Scl-70. Negative: anti SSA/Ro60, SSA/Ro52, SSB, RNP, Sm and Jo-1.

Serologies
HBV, HCV, HIV: negative. Urine sediment and urine system: pH 5.5, density 1008, protein 1+, blood 2+ (50 red blood cells/field), rest negative.

Urine electrophoresis: electrophoretic profile of mixed proteinuria: tubular and minor non-selective glomerular proteinuria.

Urine immunofixation: no monoclonal component observed.
ECG (prior to the event, at the Internal Medicine consultation): sinus rhythm at 60 beats per minute, with left anterior hemiblock and incomplete right bundle branch block.
ECG (SA MU at home): complete atrioventricular block with wide QRS leak at 20 bpm.
ECG (ED): Complete AVB with wide QRS escape alternating with transcutaneous MCP rhythm at command without capture failure.
Telemetry (ED): bouts of polymorphic torsades de pointes-like ventricular tachycardia, self-limited.
ECG (post definitive MCP): sinus tachycardia at 112 bpm with ventricular pacing by MCP with self-paced monitoring. Chest X-ray (on admission): increased cardiothoracic index with vascular redistribution and bilateral diffuse interstitial predominance pattern. Provisional MCP electrode in normal position in the RV.

Chest X-ray (during the episode of PAD): increased cardiothoracic index with bilateral diffuse alveolar pattern, predominantly right and more marked at the perihilar level, compatible with PAD. MCP generator with right atrial and ventricular electrode normally positioned.

Chest X-ray (4 days after admission, 48 hours post-PAE): increased cardiothoracic index with great improvement in the diffuse alveolar pattern, but interstitial pattern with vascular redistribution persists. MCP generator with normopositioned right atrial and ventricular electrode. Transthoracic echocardiogram (TTE): LV of normal size and thickness, with mildly impaired systolic function. Prolonged diastolic relaxation pattern. Severe hypokinesia of mid and apical septal segments. RV of normal size and systolic function. Mitral valve with thickened leaflets, with moderate insufficiency. Tricuspid valve with mild insufficiency. Estimated PSAP of 37 mmHg. Aortic root of normal size. No pericardial effusion.

Abdominal echo: homogeneous splenomegaly of 15 cm in length without other alterations.

Chest CT scan: bicameral pacemaker.

Cardiomegaly. Increase in the calibre of the pulmonary artery compatible with pulmonary hypertension. Increased density in "ground glass" with predominance in posterior segments of both lung fields compatible with pulmonary oedema over underlying pulmonary fibrosis. Calcified mediastinal and bilateral hilar calcified adenopathies of chronic inflammatory character. Coronary angiography: epicardial coronary arteries without significant angiographic stenosis. Left dominance with CD of scarce development and course.

Renal biopsy: marked interstitial fibrosis in 40% of the sample. Tubular atrophy with thickening and folding of the tubular basement membrane. No interstitial inflammatory infiltrate. Medium-sized arteries show marked intimal thickening, with deposition of mucinous material in the intima. Arterioles with media proliferation with severe luminal involvement (90% of arteries). No fibrin thrombi or fibrinoid necrosis. 20 glomeruli were studied, in all of them there was retraction of the ball, with an increase in Bowman's space, folding of the glomerular capillary walls and 2 glomeruli with small aneurysms. No necrotising lesions. Immunofluorescence: C1q: (-), C3: (+) focal mesangial granular, C4: (-), IgA: (-), IgG: (-), IgM:(-), albumin: (+) in tubular basement membranes and Bowman's capsule, fibrinogen: (-) kappa and lambda light chains:(-).

Summary: tubulointerstitial nephropathy with severe involvement and secondary vascular changes.

EVOLUTION
The patient was admitted to the coronary unit where a provisional pacemaker was implanted via the right jugular vein, maintaining the MCP rhythm in a command regime and without any new rhythm alterations being observed in the telemetry. Haemodynamically stable with normal baseline blood gases and BP 160/90, amlodipine 5 mg/12h was added to the usual treatment (without diltiazem). Transthoracic echocardiography (TTE) showed a non-dilated LV with severe hypokinesia of the middle and apical septal segments, slightly impaired systolic function, prolonged relaxation with non-high filling pressures, right chambers of normal size and function, mitral insufficiency grade II/IV and PSAP 37+PVC. The following morning, DDDR definitive MCP was implanted, being in MCP rhythm on command and with no new pathological findings on monitoring, but BP 160/95 persisted despite treatment with amlodipine 10 mg/12h and doxazosin 8 mg/24h in a patient with no known chronic hypertension and with elevated renal function figures since admission.
On the afternoon of the implant, the patient began sudden dyspnoea with BP 220/130 in a situation of radiological APE with bilateral pleural effusion, respiratory acidosis with global respiratory failure requiring the start of non-invasive ventilation with BIPAP, intensive diuretic treatment, intravenous nitrates and combination with full-dose antihypertensive drugs (amlodipine, doxazosin); ACE inhibitors were not started due to renal dysfunction. A new emergent TTE was performed, which showed the previous findings. After 8 hours of treatment, there was a clear clinical, radiological and blood gas improvement, so non-invasive ventilation was withdrawn and diuretic treatment was reduced; however, persistently high BP levels persisted despite high-dose IV NTG and full doses of amlodipine and doxazosin; and the deterioration of renal function with proteinuria and haematuria was increasing, although with negative balances, accompanied by plateletopenia and anaemia with reticulocytosis. Again 72 hours after the episode of PAD, he suffered a new crisis of dyspnoea accompanied by a hypertensive crisis with figures of 190/100 with worsening renal function and oliguria.
At this point, taking into account the patient's history and the complementary tests (see section on complementary tests), a presumptive diagnosis was made, which was later confirmed with definitive diagnostic tests. Specific treatment was prescribed, with improvement of the respiratory symptoms and control of BP levels. However, the deterioration of renal function was persistent and progressive, requiring a right femoral catheter for haemodialysis. Subsequently, a renal biopsy was performed which revealed tubulointerstitial nephropathy and vascular involvement that led to stage V renal disease with the need for renal replacement therapy. A right jugular tunnelled catheter was placed and the patient was discharged home (day 58 since admission) on an outpatient chronic haemodialysis programme. Subsequent outpatient evolution was very unfavourable and despite specific treatment and haemodialysis first every 48 hours and then daily, the patient died two months later.

DIAGNOSIS
Diffuse systemic sclerosis with scleroderma renal crisis.
Pulmonary fibrosis 2nd to pulmonary involvement of diffuse systemic sclerosis.
Complete atrioventricular block, myocardial fibrosis and mild ventricular dysfunction 2nd to cardiac involvement of diffuse systemic sclerosis.
