Online Clinical Case Study (March 2016)

Clinical Cardiology Series
臨床心臟科個案研究

The content of the March Cardiology Series is provided by:
Dr. WONG Chi Yuen MBBS (HK), MRCP (UK), FHKCP, FHKAM (Med), Specialist in Cardiology
三月臨床心臟科個案研究之內容承蒙黃志遠醫生提供。

Stroke prevention in atrial fibrillation

For each of the patients with atrial fibrillation below, select the appropriate approaches for stroke prevention (more than one answer is possible).

Options:

A. No drug or intervention
B. Aspirin
C. Warfarin
D. Novel Oral Anticoagulants (NOAC)
E. Non-pharmacological intervention

Patients:

  1. A 50-year-old man with paroxysmal atrial fibrillation mainly presents with palpitation. He does not have any other cardiovascular risk factors. His echocardiogram is unremarkable
  2. A 70-year-old lady with asymptomatic persistent atrial fibrillation, diabetes mellitus and hypertension. There is no heart murmur on physical examination.
  3. A 68-year-old lady with asymptomatic persistent atrial fibrillation and chronic rheumatic heart disease. Her echocardiogram shows mild mitral stenosis, normal left ventricular ejection fraction and absence of cardiac thrombus.
  4. A 63-year-old man with asymptomatic paroxysmal atrial fibrillation who has suffered 2 episodes of transient ischaemic attack. His cardiovascular examination was unremarkable.
  5. A 55-year-old lady with asymptomatic atrial fibrillation and mitral valve replacement with mechanical valve. She is taking warfarin. She asks if alternative drugs can be used to avoid blood monitoring.
  6. An 80-year-old man with atrial fibrillation, hypertension and prior history of stroke. He has been taking warfarin with stable INR range (2-2.5). Recently he suffers from subdural hemorrhage complicating accidental fall with fair recovery. Physician is consulted for restarting stroke prevention therapy.
1. Patient 1.
  A
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2.

Patient 2.

  C, D
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3. Patient 3.
  C
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4. Patient 4.
  C, D
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5. Patient 5.
  C
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6. Patient 6.
  C, D, E
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Answer

Patients with atrial fibrillation are at increased risk of arterial embolization irrespective of a rate or a rhythm control strategy. Left atrial appendage is comprised of pectinate muscle which favors blood stasis, and is the most common location (> 90 percent) for thrombus formation. Ischaemic stroke is the most frequent (and often disabling) form of embolization associated with atrial fibrillation.

Decision on stroke prevention strategy needs to be individualized. The CHA2DS2-VASc score is the most commonly used (and recommended) for risk stratification in patients with non-valvular atrial fibrillation:

Congestive heart failure 1 point
Hypertension 1 point
Age >= 75 2 points
Diabetes mellitus 1 point
Stroke/Transient Ischaemic Attack 2 points
Vascular disease
(myocardial infarction, peripheral vascular disease)
1 point
Age 65-74 1 point
Sex (female) 1 point
Maximum score 9 points

Patients with score 0-1 points have estimated annual stroke risk of 0.2% - 0.6%, whereas those with >=2 points have the risk ranging from 2.2% to 12.2%. The guidelines from European Society of Cardiology (2012) and American Heart Association/American College of Cardiology/Heart Rhythm Society (2014) both recommend that for low risk patients with non-valvular atrial fibrillation (CHA2DS2-VASc score = 0), no antithrombotic therapy is required. For patients with CHA2DS2-VASc score >= 2, strong recommendation is given to initiate antithrombotic therapy with either warfarin or NOAC (direct thrombin inhibitor - dabigatran; or factor Xa inhibitor - rivaroxaban, apixaban). For patients with CHA2DS2-VASc score of 1, no therapy or treatment with oral anticoagulant or aspirin (+/- clopidogrel) may be considered after individual assessment of bleeding risk and patient's preference.

Although NOAC has the advantages of fewer dietary restrictions and blood monitoring, it should not be given to patients with atrial fibrillation secondary to mitral stenosis, those with mechanical heart valve replacement, and those with end-stage chronic kidney disease (creatinine clearance < 15 ml/min, whether on dialysis or not).

Bleeding complications are often concerned by patients receiving anticoagulation therapy. Bleeding risk can be assessed by HAS-BLED score:

Hypertension 1 point
Abnormal liver or renal function 1 point each (2 max)
Stroke 1 point
Bleeding tendency 1 point
Labile INR (while taking warfarin) 1 point
Elderly (age >65) 1 point
Drug (antiplatelet or NSAID) or Alcohol 1 point each (2 max)
Maximum 9 points

Patients with HAS-BLED score >=3 have increased bleeding risk. Caution should be taken in prescribing anticoagulation therapy but high HAS-BLED score per se should not be used to exclude patients from warfarin or NOAC. In patients who have sustained major bleeding (including intracranial hemorrhage) while on anticoagulants, resumption of therapy can be considered after efforts have been made to correct all potentially reversible bleeding risk factors. However, if bleeding risk is unacceptably high or contraindications for anticoagulants exist, percutaneous closure of left atrial appendage (>90% of embolic source in atrial fibrillation) may be considered to alleviate the need of long term drug therapy (Figure 1). These patients should be referred to cardiologists for further evaluation.


Figure 1. Example of percutaneous left atrial appendage occlusion (LAAO).

Reference:

Friberg L, Rosenqvist M, Lip GY. Net clinical benefit of warfarin in patients with atrial fibrillation: a report from the Swedish atrial fibrillation cohort study. Circulation 2012; 125:2298.

Banerjee A, Lane DA, Torp-Pedersen C, Lip GY. Net clinical benefit of new oral anticoagulants (dabigatran, rivaroxaban, apixaban) versus no treatment in a 'real world' atrial fibrillation population: a modelling analysis based on a nationwide cohort study. Thromb Haemost 2012; 107:584.

Lip GY. Implications of the CHA(2)DS(2)-VASc and HAS-BLED Scores for thromboprophylaxis in atrial fibrillation. Am J Med. 2011 Feb;124(2):111-4.

Meier B, Blaauw Y, Khattab AA, et al. EHRA/EAPCI expert consensus statement on catheter-based left atrial appendage occlusion. Europace 2014; 16:1397.

Blackshear JL, Odell JA. Appendage obliteration to reduce stroke in cardiac surgical patients with atrial fibrillation. Ann Thorac Surg 1996; 61:755.


Dermatology Series 皮膚科病例研究

Dermatology Series for March 2016 is provided by:
Dr. KWAN Chi Keung, Dr. TANG Yuk Ming, William, Dr. CHAN Hau Ngai, Kingsley, Dr. CHANG Mee, Mimi and Dr. LEUNG Wai Yiu
Specialists in Dermatology & Venereology
三月皮膚科個案研究之內容承蒙關志強醫生鄧旭明醫生陳厚毅醫生張苗醫生梁偉耀醫生提供。

Dry and scaly lower limbs

A 45 year-old man with good past health complained that he had itchy and dry skin, in particular, the lower limbs for about 3 to 4 years. Physical examination revealed dry rough skin and symmetrical scaling on both lower limbs. The scales were small, fine and polygonal in shape.

 

Answers

1. What are the differential diagnoses?
The differential diagnoses include ichthyosis vulgaris, asteatotic eczema, allergic contact dermatitis and drug eruption.
 

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2. What is the diagnosis?
The diagnosis is ichthyosis vulgaris. There are two forms of ichthyosis vulgaris - hereditary and acquired. It is the acquired form in this case.
 

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3. What is the underlying pathology?

Ichthys in Greek means fish. Hereditary ichthyosis vulgaris is an autosomal dominant genetic disorder due to altered profilaggrin expression. This affects the function of filaggrin protein, an important protein for maintaining skin barrier function. Loss of filaggrin function leads to scaling and increased transepidermal water loss. The acquired form is associated with systemic diseases particularly haematological malignancy and HIV infection.

 

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4. What investigation would you like to order?
Since acquired ichthyosis is associated with systemic diseases like haematological malignancy, sarcoidosis, leprosy, thyroid disease, hyperparathyroidism, chronic renal failure, HIV infection and autoimmune diseases such as SLE, dermatomyositis. So, investigations should be directed along the line of these systemic diseases.
 

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5. How do you treat this patient?
  There is no definitive treatment. Frequent and liberal use of topical emollient can improve the dryness. Topical retinoids may be benefits. Treating the underlying diseases is essential.
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