Accepted Manuscript An Unusual Case of Cardiogenic Shock: Common cause from uncommon etiology Katie M. Giles, MD, FRCPC Rajeev V. Rao, MD, FRCPC Kathryn J. Ascah, MD, FRCPC, FACC John P. Veinot, MD, FRCPC Buu-Khanh Lam, MD, CM, MPH, FRCSC Michael Froeschl, MD, CM, MSc, FRCPC PII:

S0828-282X(14)00107-X

DOI:

10.1016/j.cjca.2014.02.013

Reference:

CJCA 1123

To appear in:

Canadian Journal of Cardiology

Received Date: 8 January 2014 Revised Date:

13 February 2014

Accepted Date: 18 February 2014

Please cite this article as: Giles KM, Rao RV, Ascah KJ, Veinot JP, Lam B-K, Froeschl M, An Unusual Case of Cardiogenic Shock: Common cause from uncommon etiology, Canadian Journal of Cardiology (2014), doi: 10.1016/j.cjca.2014.02.013. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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An Unusual Case of Cardiogenic Shock: Common cause from uncommon etiology Katie M. Giles, MD FRCPCa Rajeev V. Rao, MD FRCPCa

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Kathryn J. Ascah, MD FRCPC FACCa John P. Veinot, MD FRCPCb

Michael Froeschl, MD CM MSc FRCPCa

Divisions of Cardiology and Cardiac Surgery, University of Ottawa Heart Institute,

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a

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Buu-Khanh Lam, MD CM MPH FRCSCa

Ottawa, Ontario, Canada b

Division of Anatomical Pathology, University of Ottawa, Ottawa, Ontario, Canada

Corresponding Author:

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Michael Froeschl, MDCM MSc FRCPC University of Ottawa Heart Institute

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40 Ruskin Street Ottawa ON K1Y 4W7

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Phone: (613) 761-4049 Fax: (613) 761-5212

Email: [email protected]

Short Title: An Unusual Case of Cardiogenic Shock Word Count: 1452

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Brief Summary: We present a patient with an acute coronary syndrome complicated by cardiogenic shock. Severe mitral regurgitation due to an unusual etiology was diagnosed.

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Management strategies are discussed in a branched self-assessment format designed to challenge the reader’s clinical judgment.

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Abstract: Mechanical complications of an acute coronary syndrome can lead to

hemodynamic instability out of proportion to the degree of left ventricular dysfunction.

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We present the case of a patient with cardiogenic shock secondary to severe mitral regurgitation in the setting of an acutely occluded obtuse marginal artery. Echocardiography and pathologic findings revealed an uncommon etiology of anterolateral papillary muscle rupture. Using the unique features of this case, we present a clinical self-assessment exercise highlighting the challenges involved in the

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management of this type of patient.

Clinical Presentation: A 65 year-old paraplegic male with Type 2 diabetes presented

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with a two-week history of malaise. He was diagnosed with obstructive uropathy and underwent percutaneous nephrostomy tube insertion.

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Immediately after the procedure, the patient developed fever and leukocytosis and

was admitted to hospital. The presumed source was genitourinary and he received fluid resuscitation and antibiotics. Physical examination revealed a superficial ulcer on the right hip without purulent drainage. Initial blood and urine cultures were negative. Two days post-admission, he continued to have fevers above 38°C. On day three, he reported chest pain and was diaphoretic. Vital signs revealed severe hypotension (68/45),

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tachycardia, and hypoxia. Electrocardiography (ECG) demonstrated ST-depression in leads V2-V4, II, III and aVF. Chest x-ray revealed pulmonary edema. He was transferred to the ICU for ventilatory and vasopressor support. Examination revealed cool

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extremities and a soft, pan-systolic murmur at the apex. Initial troponin-I (TnI) was

elevated at 1.6 µg/L (normal < 0.02 µg/L). The patient received aspirin and clopidogrel. Cardiology was consulted. Bedside focused ultrasound with limited views suggested a

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posterior wall motion abnormality, grossly normal LV function and moderate mitral

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regurgitation (MR). A diagnosis of cardiogenic shock was made.

Question #1: How do you proceed? (a)

Continue with medical stabilization, IV heparin and broadening of

24 hours. (b)

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antimicrobial coverage. Transthoracic echocardiogram (TTE) within

Transfer to PCI-capable centre for urgent cardiac

Stat formal TTE plus transesophageal echocardiogram (TEE) if required.

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(c)

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catheterization.

Commentary

We elected to transfer the patient for urgent cardiac catheterization. Though the

clinical course suggested sepsis in the days leading up to his acute decompensation, the symptoms, physical exam, ECG changes, and TnI elevation supported an acute coronary syndrome (ACS) complicated by cardiogenic shock. There are several potential

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mechanisms of cardiogenic shock in this patient. A large territory of myocardial ischemia can result in acute, severe LV systolic dysfunction. Mechanical complications of acute myocardial infarction leading to shock include rupture of the interventricular

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septum or papillary muscle. Takotusbo cardiomyopathy (apical ballooning syndrome) is clinically indistinguishable from ACS and requires angiography for diagnosis1. The

preceding septic picture raises the possibility of infective of endocarditis. Cardiogenic

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shock may result from embolism of vegetation material causing myocardial ischemia or valvular destruction.

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Option (a) would delay diagnosis and treatment of potentially reversible mechanisms of shock. While (c) is a reasonable approach, delineating coronary anatomy may be vital to establishing a diagnosis and it introduces a potential delay to

The Case Continues

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revascularization if an ACS has caused the patient’s decline.

Coronary angiography revealed a right dominant system with a hazy, 99%

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stenosis, TIMI 2 flow in the 1st obtuse marginal branch (OM1) of the left circumflex artery (LCx) and non-obstructive disease elsewhere. Since the coronary anatomy was out

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of keeping with his hemodynamics, a search for mechanical complications was initiated. Left ventriculography documented severe MR. The posterolateral wall appeared akinetic and EF was preserved by visual estimate. Urgent TEE and cardiac surgery referrals were arranged.

Commentary

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What are the potential mechanisms of MR in this setting? The rapid clinical deterioration suggested an acute process causing significant regurgitation. Acute MR of native valves can result from ischemia causing papillary muscle dysfunction and leaflet

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restriction (ischemic MR) or rupture of the papillary muscle. The posteromedial (PM)

papillary muscle is more susceptible to ischemia, as it generally has a single blood supply from the posterior descending artery (PDA). The anterolateral (AL) papillary muscle is

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less vulnerable to ischemia as it typically has a dual blood supply from the left anterior descending (LAD) and LCx arteries. Severe LV dysfunction with ventricular dilation can

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result in acute MR, but left ventriculography does not support this as an etiology here. Multiple mechanisms of acute MR can occur in the setting of infective endocarditis (IE), including leaflet perforation, vegetation interfering with valve closure, mitral annular abscess or chordal rupture. Myxomatous degeneration, though less likely

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here, can lead to rupture of chordae or degeneration of the leaflets. Acute rheumatic fever causing rupture of chordae is possible, but extremely rare2. Two separate mechanisms causing hemodynamically significant MR have been

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reported in the setting of Takotsubo cardiomyopathy (TTC). The mitral valve can become tethered due to LV dilatation and dysfunction3. Systolic anterior motion (SAM) of the

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MV has also been reported, thought to be caused by basal hyperkinesis and potentially creating subvalvular obstruction4. Here, the lack of apical dysfunction argues against TTC.

Question #2:

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While awaiting TEE and likely surgical mitral valve replacement, what is the most appropriate course of action? (a)

PCI and stenting of the culprit marginal artery plus intra-aortic balloon

IABP insertion alone

(c)

PCI and stenting alone

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(b)

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pump insertion (IABP)

The Case Continues

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As the patient had already received dual antiplatelet therapy, PCI with a bare metal stent was performed on the OM1 to restore antegrade flow. Though obstruction of an obtuse marginal would be unlikely to compromise papillary muscle perfusion with classic anatomy, several published reports have documented papillary muscle rupture

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during single vessel ACS of the left system, including during isolated OM1 STEMI5. In this case, revascularization carried potential benefit and little risk of added harm. TEE confirmed severe MR and documented rupture of the anterolateral papillary

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muscle (Figure 1, Online Video Data Supplement). The possibility of vegetation on the anterolateral papillary muscle was raised. Given the acute, severe MR and cardiogenic

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shock, an IABP was indicated. However, severe flexion contractures at the hips were deemed a contra-indication to insertion via femoral access. Given the short delay to OR, risk of brachial IABP access was considered to outweigh the benefit and he was moved to the OR without an IABP.

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Intraoperatively, vegetations were found eroding into the tip of the anterolateral papillary muscle, causing rupture. The anterior mitral leaflet was also involved, with

Question #3:

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vegetations predominantly found on the lateral and middle (A1 and A2) scallops.

Given the intraoperative findings, why was the presentation consistent with an ACS? Embolism of vegetation material down the OM1

(b)

Rupture of the papillary muscle and subsequent acute pulmonary edema

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(a)

(c)

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led to a catecholamine surge, triggering the plaque rupture. Decreased cardiac output and elevated LVEDP caused diffuse subendocardial ischemia, particularly in an already compromised OM1 territory.

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Commentary

The possibility of embolic phenomenon causing the original ACS was raised; however, the angiographic appearance of the lesion was consistent with coronary artery

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disease as a culprit. Furthermore, the hazy appearance of the lesion and compromised antegrade flow suggested this was an acute lesion, as opposed to a chronic stenosis

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(Online Video Data Supplement, Video 2). However, determining acuity is an inexact science and the possibility of a pre-existing plaque chronically compromising the OM1 territory remains. Pathologic examination of the papillary muscle revealed suppurative inflammation with necrosis plus areas of fibroblastic myocardial healing. Gram stain showed numerous gram-positive cocci and silver stain confirmed large numbers of cocci bacteria. There was no evidence of ischemia or emboli within the papillary muscle. This

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is consistent with active IE causing papillary muscle necrosis and rupture and does not support decreased perfusion as a contributor. Acute, severe MR resulting in profound hypotension and pulmonary edema induced an abrupt change in our patient’s clinical

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status. It is plausible that the resultant catecholamine surge contributed to a secondary

acute plaque rupture. Increases in heart rate, systemic vascular resistance and coronary vasoconstriction could have disrupted a vulnerable plaque.

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The patient underwent successful mitral valve replacement and treatment for

infective endocarditis. Hospitalization was prolonged due to multiple comorbidities, but

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after five months he was discharged to a rehabilitation facility and his cardiac condition remained stable.

Teaching Points

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1) A mechanical complication of acute myocardial infarction should be considered in the presence of cardiogenic shock.

2) Though acute mitral regurgitation in the setting of cardiac ischemia is commonly

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attributed to restriction or rupture of the posteromedial papillary muscle due to impaired perfusion, other etiologies should be considered. The presence of features suggestive of

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IE, rheumatic fever or TTC, among others, should raise suspicion of an alternate etiology.

Disclosures: The authors have no conflicts of interest to disclose.

REFERENCES 1.

Prasad A, Lerman A, Rihal CS. Apical ballooning syndrome (Tako-Tsubo or stress cardiomyopathy): a mimic of acute myocardial infarction. Am Heart J.

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2008;155(3):408–417. doi:10.1016/j.ahj.2007.11.008. Hwang WS, Lam KL. Case reports. Rupture of chordae tendineae during acute rheumatic carditis. Br Heart J. 1968;30(3):429–431.

3.

Izumo M, Nalawadi S, Shiota M, et al. Mechanisms of acute mitral regurgitation in patients with takotsubo cardiomyopathy: an echocardiographic study. Circ Cardiovasc Imaging. 2011;4(4):392–398. doi:10.1161/CIRCIMAGING.110.962845.

4.

Rao RV, Wright D, Dokainish H. Acute mitral regurgitation in suspected acute coronary syndrome: what is the cause? Echocardiography. 2013;30(5):E118–20. doi:10.1111/echo.12159.

5.

Vieira C, Gaspar A, Alvares Pereira M, Salomé N, Almeida J, Amorim MJ. Ischemic rupture of the anterolateral papillary muscle. Rev Port Cardiol. 2013;32(3):243–246. doi:10.1016/j.repc.2012.06.014.

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2.

Figure Legend

Figure 1. A. Four-chamber TEE view demonstrating a ruptured anterolateral papillary

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muscle, flail posterior leaflet and an echo-lucent space in the papillary muscle reflecting possible infection. B. Mid-esophageal long axis view showing severe MR

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on colour Doppler. Online Videos 1A and 1B correspond to panels A and B.

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Online Video Data Supplement, Video 2. Coronary angiography demonstrating a 99% stenosis and TIMI 2 flow in the 1st obtuse marginal branch of the left circumflex artery.

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An unusual case of cardiogenic shock: common cause from uncommon etiology.

Mechanical complications of an acute coronary syndrome can lead to hemodynamic instability out of proportion to the degree of left ventricular dysfunc...
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