Running Title: Acute Flail Mitral Valve in Thyroid Storm

Transcription

1 AACE Clinical Case Reports Rapid Electronic Articles in Press Rapid Electronic Articles in Press are preprinted manuscripts that have been reviewed and accepted for publication, but have yet to be edited, typeset and finalized. This version of the manuscript will be replaced with the final, published version after it has been published in the print edition of the journal. The final, published version may differ from this proof. Case Report ACCR Flail Mitral Valve A rare complication of a thyroid storm Abel Weiliang, Chen, MBBS, MRCP (UK), MMed (Int Med); Hui Chia, Wee, MBBCh, MRCP (UK); Vikram, Sonawane, MBBS, MRCP (UK) Running Title: Acute Flail Mitral Valve in Thyroid Storm From: Department of General Medicine, Division of Endocrinology, Khoo Teck Puat Hospital, Singapore Corresponding Author: Abel Weiliang, Chen, MBBS, Khoo Teck Puat Hospital 90 Yishun Central Singapore chenweiliangabel@gmail.com

2 ABSTRACT OBJECTIVES Thyroid storm is a life-threatening presentation, with heart failure and tachyarrhythmias being common manifestations. This case highlights that a flail mitral valve from chordae tendineae rupture can be a cause of worsening heart failure and cardiogenic shock in a thyroid storm, albeit a rare complication. METHODS We describe a patient who was admitted for a thyroid storm precipitated by pneumonia, who later developed an acute flail mitral valve from chordae tendineae rupture. RESULTS A 55 year-old lady with no past medical history was admitted with fever, dyspnea, lower limb swelling and hemoptysis. She was febrile, tachycardic and in fluid overload. Her heart sounds were dual and no murmurs were heard. Initial investigations indicated primary hyperthyroidism and pneumonia. She was diagnosed with a thyroid storm precipitated by a pneumonia, complicated by heart failure. Her Burch-Wartofsky score was 70. She was started on IV hydrocortisone, PO propylthiouracil, PO lugols s iodine and PO cholestyramine, together with IV amoxicillin-clavulanate and IV furosemide. She continued to deteriorate in the Medical Intensive Care Unit with worsening hypoxia and hypotension. Echocardiography showed an acute flail posterior mitral valve leaflet with torrential mitral regurgitation from rupture of the chordae tendineae. She subsequently underwent a bioprosthetic mitral valve replacement. CONCLUSION An acute flail mitral valve precipitated by thyroid storm leading to refractory cardiogenic shock is rare. Factors contributing to the rupture of valve chordae tendineae include the effect of hyperthyroidism on papillary muscle function, a hyperdynamic circulation leading to vulvular stress, as well as pre-existing mitral valve pathology. MAIN ARTICLE

3 Abbreviations: RI = Reference Index; TS = thyroid storm. INTRODUCTION Thyroid storm is a life-threatening presentation with mortality of about 10% to 30%. (1) Patients with undiagnosed longstanding thyrotoxicosis could also have underying thyrocardiac disease. In addition, mitral valve abnormalities, especially prolapse, are also common in the general population. Here, we describe a patient who presented with a thyroid storm complicated by an acute flail mitral valve from acute chordae tendineae rupture, leading to severe heart failure and cardiogenic shock. CASE PRESENTATION A 55 year-old lady of Chinese ethnicity was referred by her general practitioner to the emergency department for a 3-day history of fever, dyspnea, lower limb swelling and one episode of hemoptysis. She denied any recent travel or sick contacts. She had no past medical history. On examination, she was febrile at 38.7 degrees celsius with a blood pressure of 140/54 mmhg, a pulse rate of 140 beats per minute and was saturating 96% on 2 litres of oxygen. She noted to be mildly agitated and had pedal edema. She was confused and not oriented to time, place or person. Her heart sounds were dual and no murmurs were heard. A respiratory examination revealed leftsided basal crepitations. Of note, she had a large diffuse goitre, but had no signs of thyroid eye disease. Initial blood tests revealed the following: white blood cell count x109/l (Reference Index: ), haemoglobin 11.2 g/dl (RI: ), platelets 237 X109/L (RI: ), free thyroxine 75.6 pmol/l (RI: 12-22), thyroid stimulating hormone <0.005 miu/l (RI: ), sodium 136 mmol/l (RI: ), potassium 3.0 mmol/l (RI: ), creatinine 72 umol/l (RI: 45-84), urea 11.7 mmol/l (RI: ), adjusted calcium 2.4 mmol/l (RI: ), phosphate 1.13 mmol/l (RI: ), magnesium 0.8 mmol/l (RI: ) (RI), alanine aminotransaminase 18 U/L (RI: 10-36), aspartate aminotransaminase 16 U/L (RI: 10-30), alkaline phosphatase 146 U/L (RI: ), total bilirubin 28 umol/l (RI: 3-21), pro brain natriuretic peptide pg/ml (RI: 5-125). An electrocardiogram showed sinus tachycardia with a rate of 140 beats per minute, and a chest radiography showed bilateral lower airspace opacifications. As such, she was diagnosed to have a thyroid storm precipitated by a pneumonia, complicated by congestive heart failure, and on a background of newly-diagnosed primary hyperthyroidism. Her Burch-Wartofsky score on admission was 70 (15 points for temperature, 10 points for agitation, 10 points for precipitating event, 10 points for moderate heart failure, 25 points for tachycardia), with total score of more than 45 being highly suggestive of a thyroid storm. (1) Based on the Japan Thyroid Association criteria, she was classified as TS2 (definite thyroid storm) due to the presence of restlessness, fever, tachycardia and congestive heart failure. (2) She was started on IV hydrocortisone 100mg 8H, PO propylthiouracil 200mg 4H, PO lugols s iodine 10 drops 8H and PO cholestyramine 4g TDS, together with IV amoxicillin-clavulanate and IV furosemide 40mg. Beta-blockers were held off due to congestive cardiac failure as well as the development of hypotension, in order to avoid precipitating a cardiovascular collapse.

4 She was initially admitted to the General Ward but deteriorated 2 hours after arrival. She was transferred to the Medical Intensive Care Unit due to worsening hypoxia as well as hypotension. Continuous positive airway ventilation and a noradrenaline infusion was started to support her breathing and blood pressure respectively. Despite the measures, her vasopressor requirements continued to increase rapidly over the next few hours. She was subsequently intubated for worsening hypoxia, metabolic acidosis and refractory hypotension. A repeat cardiovascular examination demonstrated the presence of a new systolic murmur over the mitral area. Bedside trans-thoracic 2D Echocardiography showed a flail posterior mitral valve leaflet with torrential mitral regurgitation, severe pulmonary hypertension, dilated atria, and hyperdynamic left ventricular function. A repeat chest radiograph demonstrated worsening diffuse airspace opacification. She was emergently referred to the Cardiology and Cardiothoracic Surgery services. In view of her refractory hypotension, overt heart failure and echocardiography findings, an intra-aortic balloon pump was inserted. A coronary angiogram was also done (which showed normal coronary arteries), and she was immediately transferred to another nearby tertiary centre for an urgent mitral valve repair. Pre-surgery trans-esophageal echocardiography confirmed a pre-existing posterior mitral valve prolapse with an acute flail due to rupture of the chordae tendineae, as well as a moderate tricuspid regurgitation. She subsequently underwent a bioprosthetic mitral valve replacement and a tricuspid valve repair. At this time, her thyroid receptor antibody returned elevated at 6.6 IU/L (RI: <1.8), indicative of Graves disease. Her clinical condition stabilised subsequently and she was subsequently transferred to a community hospital for rehabilitation. DISCUSSION Thyroid storm is generally uncommon, with most sources reporting its occurrence in 1% to 5.4% patients admitted for thyrotoxicosis. (1,2,3) The exact mechanisms underlying the development of thyroid storm is not understood, but probably involves a heightened response to thyroid hormone along with increased or abrupt availability of free hormones and enhanced binding to thyroid hormone receptors. Adrenergic activation also plays a major role in thyroid storm. This is due to enhanced responsiveness to endogenous catecholamines in the hyperthyroid state due to an increase in tissue specific beta-adrenergic receptor density or modification in post-receptor signalling pathways mediated by tri-iodothyronine. (4) Thyrocardiac disease is thought to be contributed by the inotropic and chronotropic effects of thyroid hormones, which result in changes in cardiac rhythmicity (e.g. atrial fibrillation) or heart muscle function (e.g. hypertrophy and biventricular enlargement). (5) Epidemiologically, mild to moderate mitral regurgitation is common in thyroid storm and has been noted to occur in up to 13% of such patients. (6) A previous study also noted an association between mitral valve prolapse and hyperthyroidism, with the former found in 43% of hyperthyroid patients versus 18% in a control group. (7). Large studies have also shown that the majority (90%) of cases with spontaneous chordae tendineae rupture had associated underlying mitral valve prolapse. (8,9). However, with all factors taken all, spontaneous chordae tendineae rupture during a thyroid storm and underlying mitral valve prolapse is very rare (10). Excess thyroid hormone induces intrinsic papillary muscle disease by its direct effects on the heart and circulation (11). At the same time, the prolapsed mitral valve, containing defective collagen

5 fibrils and excess spongiosa, appears to withstand elevated left ventricular systolic pressures poorly compared with the normal mitral valve, resulting in an increased tendency to chordae tendineae rupture. (12) Lastly, thyrotoxicosis and fever leads to an increased cardiac output with a consequent increased systolic stress on the left ventricle and mitral valve. (10) In view of the fairly abrupt worsening of her condition around the time a new systolic murmur at the mitral area was heard, it is conceivable that the development of the thyroid storm had preceded the rupture of the chordae tendineae. In this case, the patient s pre-existing mitral valve prolapse, coupled with the severe hyperthyroidism causing papillary muscle dysfunction and a hyperdynamic leading to further stress on the mitral valve led to a near-catastrophic complication. CONCLUSION Overall, an acute flail mitral valve precipitated by thyroid storm leading to refractory cardiogenic shock is rare. Such an event is predisposed by the thyrotoxicosis itself, as well as pre-existing mitral valve pathology. Given the potential catastrophic consequences, a high index of suspicion is needed. REFERENCES 1. Nayak B, Burman K. Thyrotoxicosis and thyroid storm. Endocrinol Metab Clin North Am. 2006;35: Burch H, Wartofsky L. Life-threatening thyrotoxicosis. Thyroid storm. Endocrinol Metab Clin Nort Am 1993; 22: Akamizu,T, Satoh T, Isozaki O at al. Diagnostic Criteria, Clinical Features, and Incidence of Thyroid Storm Based on Nationwide Surveys Thyroid. 2012; 22: Feldt-Rasmussen U, Emerson CH. Further thoughts on the diagnosis and diagnostic criteria for thyroid storm. Thyroid. 2012;22: Chiha M, Samarasinghe S, Kabaker A. Thyroid storm: an updated review. J Intensive Care Med. 2015;30: Mercé J, Ferrás S, Oltra C, et al. Cardiovascular abnormalities in hyperthyroidism: a prospective Doppler echocardiographic study. Am. J. Med. 2005;118: Channick B, Adlin E, Marks A, et al. Hyperthyrodism and mitral valve prolapse. N Eng J Med 1981;305:

6 8. Jeresaty R, Edwards J, Chawla S. Mitral valve prolapse and ruptured chordae tendineae. Am J Cardiol 1985;55: Hickey A, Wicken D, Wright J, et al. Primary (spontaneous] chordal rupture: relation to myxomatous valve disease and mitral valve prolapse. JACC 1985;5: Aronson R, Hoffman M, Algueti-Margulis A, et al. Spontaneous rupture of mitral chordae tendineae in hyperthyroidism. Am. J. Cardiol. 1987;59: Reynolds J, Woody H. Thyrotoxic Mitral Regurgitation A Probable Form of Intrinsic Papillary Muscle Dysfunction. Am J Dis Child. 1971;122: Roberts WC. Mitral valve disease and systemic hypertension. Am J Cardiol 1985:5: