Clinical Case Analysis: Mixed Connective Tissue Disease (MCTD) with PAH

Diagnosis

Explaining the Clinical Course

Why she deteriorated on Methotrexate + Leflunomide + Methylprednisolone:

• Weight loss and anorexia - nausea, stomatitis, hepatotoxicity, and anorexia are among the most common adverse effects of methotrexate
• Oral ulcers - may have been worsened by methotrexate (folic acid antagonism)
• Psychiatric disturbances / irritability - methotrexate neurotoxicity is documented; leflunomide can also contribute

Current Management Assessment

What is appropriate currently:

Recommended Management Strategy

1. Disease-Modifying Treatment for MCTD (currently NOT on any DMARD)

• Hydroxychloroquine (HCQ) is the cornerstone of MCTD treatment - used in 85.8% of patients
• HCQ at diagnosis was associated with significantly less development of ILD or PAH (p<0.05)
• HCQ + low-dose glucocorticoids were sufficient to control disease in ~50% of patients
• DMARDs/IS were escalated for PAH and musculoskeletal involvement

2. PAH Management

• Optimize sildenafil - standard dosing for PAH is 20 mg TID (not 50 mg once), though dosing varies
• Consider adding an endothelin receptor antagonist (ERA) such as ambrisentan or macitentan for combination therapy, as PAH in CTD tends to be progressive
• Anti-coagulation consideration - PAH in CTD carries thrombotic risk (discuss risk/benefit given her age)
• Periodic RHC (right heart catheterization) to classify hemodynamic severity

3. Address the Anemia (Hb 7.8 g/dL)

• Normal creatinine (excludes renal cause)
• Normal WBC and platelets (not aplastic or drug-induced pancytopenia)
• Active MCTD with inflammatory burden

• Reticulocyte count, peripheral smear
• Serum iron, ferritin, TIBC (distinguish ACD from iron deficiency)
• Coombs test (rule out autoimmune hemolytic anemia - occurs in MCTD/SLE overlap)
• B12 and folate (especially important given prior methotrexate use, which depletes folate)

4. Low-dose Corticosteroid - Judicious Re-introduction if Needed

• Low-dose prednisolone (5-10 mg/day), not methylprednisolone
• Only if active inflammatory features (myositis, serositis, acute arthritis) are present
• With bisphosphonate bone protection
• Short course, tapering rapidly once disease controlled

5. Monitoring

6. If Disease Remains Refractory

• Rituximab (anti-CD20) - evidence in MCTD, especially for thrombocytopenia and refractory disease. Response rate ~80% for thrombocytopenic complications (Andrews' Diseases of the Skin)
• Azathioprine - better GI tolerability than methotrexate/leflunomide, safer alternative if immunosuppression needed for ILD
• Mycophenolate mofetil - increasingly used for CTD-PAH and CTD-ILD

Summary of Key Clinical Points

1. The diagnosis is MCTD - post-partum onset, anti-U1RNP+, RA factor+, multi-system involvement, PAH as the most serious complication
2. The prior drug regimen caused her side effects - methotrexate/leflunomide/high-dose steroids caused anorexia, weight loss, and psychiatric disturbances; stopping them appropriately improved symptoms
3. She is currently under-treated for MCTD - sildenafil addresses PAH but she needs a disease-modifying agent (HCQ is the best choice to restart) to reduce overall inflammation and potentially slow PAH progression
4. PAH requires escalation - moderate PAH in CTD typically needs combination therapy (PDE5i + ERA); single-agent sildenafil may be insufficient long-term
5. Anemia needs work-up - with Hb 7.8, a complete anemia panel including Coombs test is mandatory before attributing to ACD
6. Her psychiatricfeatures may be organic MCTD (CNS involvement) or drug-induced - now that steroids are off, if psychiatric symptoms recur, MCTD neuropsychiatric involvement should be considered and treated cautiously

• Murray & Nadel's Textbook of Respiratory Medicine, p. 2101
• Brenner and Rector's The Kidney, p. 1467
• Andrews' Diseases of the Skin, p. 293
• Robbins & Kumar Pathologic Basis of Disease, p. 223

Critical Appraisal of Your Current Regimen

✅ Hydroxychloroquine 200 mg BD (400 mg/day)

✅ Colchicine 0.6 mg BD

• Pericarditis/serositis in CTD/lupus
• Recurrent febrile episodes (acts on inflammasome/IL-1 pathway)
• Oral ulcers (off-label but evidence-supported)

⚠️ Nimesulide (NSAID) - Use with Caution / Reconsider

1. PAH + NSAID = Dangerous combination. NSAIDs cause sodium and water retention, increase systemic vascular resistance, and can precipitate right heart decompensation in PAH patients. In a patient already on noradrenaline (suggesting haemodynamic compromise), adding a vasoconstrictive/fluid-retaining agent is counterproductive.
2. Nimesulide is hepatotoxic - it carries a black box warning in several countries for idiosyncratic hepatotoxicity. In a patient on multiple drugs (HCQ, potentially immunosuppressed), this is an added risk.
3. NSAIDs are relatively contraindicated in SLE/MCTD overlap due to risk of aseptic meningitis, renal impairment, and fluid retention worsening cardiac status.
4. Better alternatives for fever/pain in MCTD: Paracetamol (acetaminophen) is safer for acute symptom relief. If serositis pain is the indication, colchicine (already given) + low-dose prednisolone are more appropriate.

⚠️ Inj. Methylprednisolone 250 mg IV (Pulse) - Justified but Monitor Carefully

• High-grade fever
• Tachycardia + tachypnoea
• Oral ulcers suggesting active mucosal disease
• Possible serositis/myocarditis

• Monitor for acute corticosteroid-induced psychosis post-pulse
• Do not continue high-dose steroids beyond the acute phase
• Transition to low-dose oral prednisolone (5-10 mg/day) after the pulse, not repeat high doses
• The psychiatric symptoms she developed previously were almost certainly steroid-induced, so minimize duration aggressively

🔴 Noradrenaline (Norepinephrine) 2 ml/hr Single Strength - Most Concerning Agent

• Alpha-1 stimulation raises systemic vascular resistance (SVR) - which is the intended effect to maintain coronary perfusion pressure
• However, it can also raise pulmonary vascular resistance (PVR), worsening right heart afterload
• The RV in PAH is already pressure-overloaded - increased afterload from a vasoconstrictor can precipitate complete RV failure

• The RV in decompensated PAH is dilated and underperfused
• Systemic hypotension reduces coronary perfusion to the RV (which is now perfused in both systole AND diastole)
• Maintaining MAP ≥65 mmHg with noradrenaline restores RV coronary perfusion and can actually improve RV function
• Per Giannakoulas et al. (Eur Heart J 2025, PMID 40259766): In acute RV failure, maintaining systemic pressure with vasopressors is necessary to prevent RV ischaemia

• Decompensated PAH/RV failure - norad + continue sildenafil + consider inhaled nitric oxide or nebulised iloprost
• Septic shock (she has fever, possible infection) - treat the underlying infection aggressively; norad appropriate but source control needed
• Drug-induced (was she on vasodilators that caused hypotension?) - review all medications

✅ Inj. Furosemide (Lasix) 10 mg IV - Appropriate but Needs Careful Titration

• Do not over-diurese - the RV in PAH is preload-dependent. Aggressive diuresis drops filling pressure and can worsen cardiac output further
• Target: relieve venous congestion (reduce JVP, peripheral oedema) without dropping BP
• Monitor urine output, creatinine, and electrolytes closely - hypokalaemia from furosemide + noradrenaline-driven tachycardia = arrhythmia risk

⚠️ Tab. Fluconazole 200 mg Stat - Indication Needs Justification

1. Oral candidiasis - her oral ulcers and prior steroid/immunosuppressive exposure put her at risk for oropharyngeal candidiasis. If the ulcers include thrush, a stat dose is reasonable.
2. Prophylaxis in an immunocompromised patient starting steroids - acceptable practice
3. Suspected systemic fungal infection - 200 mg stat is grossly underdosed for systemic candidiasis (requires loading 800 mg then 400 mg daily)

• Colchicine (CYP3A4 substrate) - risk of colchicine toxicity (myopathy, neuropathy, bone marrow suppression). This combination needs close monitoring or colchicine dose reduction.
• Sildenafil (CYP3A4 substrate) - can increase sildenafil levels by ~2-3x, risking hypotension

Summary Table

Most Urgent Questions to Address Right Now

1. Why is she on noradrenaline? What is her current BP/MAP? Is she in frank shock or borderline? This determines whether she needs ICU-level care.
2. Is the fever infective or disease flare? Blood cultures, procalcitonin, and urine culture are mandatory before escalating immunosuppression further. Giving IV methylprednisolone in uncontrolled sepsis can be fatal.
3. Has PE been ruled out? PAH + dilated RV + acute decompensation + tachycardia - acute pulmonary embolism must be excluded with CTPA or V/Q scan urgently, as this would completely change management.
4. Has sildenafil been continued through this acute admission? Never stop PAH-specific therapy during hospitalisation.

PAH: Full Investigations & Treatment Strategy for This Patient

PART 1 - Complete Investigation Workup for PAH

A. Confirming the Diagnosis - Mandatory Investigations

Critical note: RHC is mandatory before intensifying PAH therapy. Her 2D echo shows "moderate PAH" but echo-estimated RVSP can be inaccurate. Only RHC gives true mPAP, PAWP, and PVR - without which you cannot confirm Group 1 PAH vs Group 2 (left heart disease) or Group 3 (lung disease). - Braunwald's Heart Disease, p. 1007

B. Workup to Classify Group and Identify Comorbidities

C. Prognostic / Risk Stratification Labs

D. Cardiac MRI (if available)

PART 2 - WHO/NYHA Risk Classification Before Choosing Therapy

PART 3 - Treatment: Is Tadalafil + Ambrisentan the Right Choice?

Short Answer: YES - This is evidence-based first-line combination therapy for CTD-PAH, and is strongly supported.

The AMBITION Trial Evidence

• Design: Treatment-naïve PAH patients (n=500), randomized to:
  • Ambrisentan + Tadalafil combination
  • Ambrisentan monotherapy
  • Tadalafil monotherapy
• Primary endpoint: Composite of death, hospitalization for PAH, disease progression, or unsatisfactory clinical response
• Result at median 517 days:
  • Combination: 18% reached primary endpoint
  • Ambrisentan mono: 34%
  • Tadalafil mono: 28%
  • Combination = 50% hazard reduction vs. pooled monotherapy (HR 0.50, p<0.001)
• CTD-PAH subgroup: A dedicated subgroup analysis of the AMBITION trial for CTD-associated PAH confirmed the same benefit, making this directly applicable to your MCTD patient.

"The AMBITION trial demonstrated a clear benefit in hard-clinical events among incident, treatment-naïve PAH patients administered combination ambrisentan plus tadalafil compared with monotherapy with either agent." - Braunwald's Heart Disease, p. 1008

"The role of early, aggressive therapy with combination oral treatments was addressed in the landmark AMBITION trial." - Harrison's Principles of Internal Medicine 22E, 2025

Drug Dosing for This Patient

What About Sildenafil vs. Tadalafil?

ERA Choice: Ambrisentan vs. Macitentan vs. Bosentan

Triple Therapy - When to Consider

• Selexipag (oral IP receptor agonist) - GRIPHON trial showed 40% reduction in composite events
• Inhaled treprostinil - add-on to PDE5i + ERA
• Sotatercept (newest agent) - activin receptor II inhibitor; STELLAR trial (Phase 3 RCT, 2023) showed +40m improvement in 6MWD on top of background dual/triple therapy, with 60% of patients already on triple therapy in the trial (PMID 38012534, 39884760). FDA approved 2024. This is the most exciting development in PAH therapy in a decade.

Summary: Recommended PAH Management Plan

STEP 1 - Investigations (before escalating therapy)
   ├── RHC with vasoreactivity testing (mandatory)
   ├── V/Q scan (exclude CTEPH)
   ├── NT-proBNP + 6MWD (risk stratification)
   ├── HRCT chest (exclude ILD)
   ├── APLA panel (MCTD-SLE overlap)
   ├── LFT, TFT, HIV, Hep B/C
   └── Cardiac MRI (if available)

STEP 2 - First-Line Therapy (intermediate-risk CTD-PAH)
   ├── STOP sildenafil 50 mg OD (non-standard dosing)
   ├── START tadalafil 40 mg OD  ← PDE5 inhibitor
   └── START ambrisentan 5 mg OD → uptitrate to 10 mg at 4 weeks ← ERA
                                 [= AMBITION regimen, 50% HR reduction]

STEP 3 - If high-risk features (NYHA IV, CI <2.0, low 6MWD)
   └── Add prostacyclin (parenteral epoprostenol or inhaled iloprost)
       or refer for IV/SC treprostinil

STEP 4 - If suboptimal response at 6 months
   └── Consider adding sotatercept (STELLAR trial, 2023-24)
       or selexipag (GRIPHON trial)

STEP 5 - Supportive
   ├── Diuretics (furosemide ± spironolactone) for fluid overload
   ├── Supplemental O2 if SpO2 <92%
   ├── Digoxin if RV failure + low CO (increases CO by ~10%)
   ├── Treat anaemia (Hb 7.8 is significant - target Hb >12)
   ├── Vaccinations (influenza, pneumococcal)
   └── Supervised exercise rehabilitation

STEP 6 - Long-term
   └── Bilateral lung transplant evaluation if failing maximal medical therapy

Key Point for This Specific Patient

• Harrison's Principles of Internal Medicine 22E (2025), p. 2237
• Braunwald's Heart Disease, p. 1007-1008
• AMBITION trial: Galiè N et al. NEJM 2015; PMID 26303624
• STELLAR/sotatercept: Hoeper MM et al. Eur Respir J 2025 (PMID 39884760)

Splenic Abscesses in This Patient - A Critical Finding That Changes Everything

Why This Discovery is a Game-Changer

• The IV methylprednisolone you gave may have been the wrong move (steroids blunt the immune response needed to fight this infection)
• The noradrenaline requirement suggests she may be in septic shock from the abscesses, not purely cardiogenic shock from PAH
• The fluconazole stat dose may actually have been prescient - fungal splenic abscess is well-recognised in immunosuppressed patients

Understanding the Splenic Abscesses in Context

Why She Got Them - Risk Factors All Present

Microbiology - What Organisms Are Likely?

STEP 1: Urgent Investigations Needed NOW

Microbiological Workup (Priority)

Imaging

STEP 2: Treatment Decision for the Abscesses

The Critical Question: Drain vs Antibiotics Alone vs Splenectomy?

• These are microabscesses - too small to drain percutaneously (PCD generally requires >3-4 cm abscess)
• PCD is actually relatively contraindicated for multiple small abscesses (StatPearls, NCBI Bookshelf)
• Conservative management with targeted IV antibiotics + antifungals is the appropriate initial strategy
• Monitor with serial imaging (ultrasound every 5-7 days) to ensure no enlargement
• If any abscess enlarges beyond 3-4 cm or she deteriorates - escalate to PCD or splenectomy

STEP 3: Empirical Antimicrobial Regimen

If Bacterial Abscess Suspected (Clinical Sepsis)

Piperacillin-tazobactam 4.5g IV q6h
  OR
Meropenem 1g IV q8h (if severe sepsis/shock, prior antibiotics, hospital-acquired)

If Fungal Abscess Suspected (Multiple Small Abscesses + Immunosuppressed)

Micafungin 100 mg IV OD   ← echinocandin preferred in Candida
  OR
Caspofungin 70 mg IV loading, then 50 mg IV OD

1. Better efficacy in severely ill patients
2. No CYP interaction concerns with sildenafil/colchicine
3. Active against Candida glabrata and Candida krusei which may be fluconazole-resistant in steroid-exposed patients

If Mycobacterial Infection Suspected (not improving in 1-2 weeks)

STEP 4: Immediate Drug Changes in Her Current Regimen

STEP 5: Source Control and Surgical Consultation

• Refer to surgery + interventional radiology now for assessment
• Surgery should be on standby in case:
  • Abscesses enlarge or coalesce
  • Splenic rupture (catastrophic emergency in PAH patients)
  • She fails to respond to 5-7 days of medical therapy
• Get Infectious Disease consultation - complex host (MCTD + PAH + steroids) with rare infection

Summary - The Revised Clinical Picture

MCTD (underlying) 
  └── PAH (complication - moderate, dilated RA/RV on echo)
  └── Splenic abscesses x3 (NEW finding - likely the PRIMARY driver 
       of her current presentation: fever, tachycardia, tachypnoea, 
       weight loss, anorexia, haemodynamic instability)
       └── Possible sources:
            ├── Hematogenous spread from prior bacteraemia
            ├── Fungal (Candida) - most likely given multiple small 
            │   lesions + prior steroids + immunosuppressives
            └── Embolic from endocarditis (must be excluded by echo)

1. 🔴 Control the infection - blood cultures, empirical broad-spectrum antibiotics + antifungals, serial imaging
2. 🔴 Exclude endocarditis - echocardiogram (TTE/TEE)
3. 🟡 Stabilise haemodynamics - noradrenaline titration, continue sildenafil, careful diuresis
4. 🟡 Treat anaemia - Hb 7.8 is particularly dangerous in the context of sepsis + PAH
5. 🟢 MCTD/PAH long-term management - tadalafil + ambrisentan can be planned once infection is controlled and the patient is stabilised

• Radcliffe et al. Open Forum Infect Dis 2022 (PMID 35299986)
• Sánchez Martínez et al. Cureus 2025 (PMID 40391182) - splenic abscess + chronic corticosteroid use
• StatPearls: Splenic Abscess (NCBI Bookshelf, updated 2024)
• Gutama et al. Surg Infect 2022 - Splenectomy vs PCD systematic review