Platelets, September 2012; 23(6): 463–466

Copyright � 2012 Informa UK Ltd.

ISSN: 0953-7104 print/1369-1635 online

DOI: 10.3109/09537104.2011.640966

ORIGINAL ARTICLE

Acute ST-segment elevation myocardial infarction: A rare initialpresentation of previously undiagnosed essential thrombocythemia

ANAND SINGLA, DINESH JAGASIA, MUKESH GARG, PHILIP A LOWRY,

& DWIGHT STAPLETON

Guthrie Clinic, One Guthrie Square, Sayre, PA, USA

AbstractEssential thrombocythemia (ET) is a myeloproliferative disorder characterized by hemorrhagic and thromboticcomplications. We describe a rare case of ST-segment elevation myocardial infarction (STEMI) in a patient with previouslyundiagnosed ET, confirmed by gene mutation. A 68-year-old man presented with severe acute chest pain and was diagnosedwith STEMI. Primary coronary angiography showed severe stenosis with thrombus in the proximal left anterior descendingcoronary artery. Percutaneous aspiration thrombectomy was performed with no residual stenosis. The patient wasdischarged on antiplatelet agents, aspirin, and clopidogrel. Further investigations for intracoronary thrombus with nounderlying atherosclerotic disease revealed positive Janus kinase 2 (JAK2) V617F gene mutation, and this was consistentwith a diagnosis of ET with elevated platelet count. This case describes a rare initial presentation of previously undiagnosedET with acute STEMI and highlights the potential importance of secondary workup for non-atherosclerotic causes ofSTEMI with isolated intracoronary thrombus otherwise normal coronary vasculature with no focal atherosclerosis.

Keywords: Essential thrombocythemia, ST-segment elevation myocardial infarction

Introduction

Essential thrombocythemia (ET) is a myeloprolifera-

tive disorder characterized by pathological clonal

proliferation of megakaryocytes with persistently

elevated platelet count [1, 2]. The clinical manifesta-

tions of ET include hemorrhagic and thrombotic

complications. Recent studies have demonstrated

that thrombotic complications, especially thrombus

in the cerebral, coronary, and peripheral arteries,

are more frequent than hemorrhages in patients

with ET [3]. The incidence of acute coronary

events in patients with ET has been reported as

high as 9.4% [4].

In the medical literature, few cases of acute

myocardial infraction (AMI) have been reported in

association with ET. Here, we report a rare case of

ST-segment elevation myocardial infarction

(STEMI) as the first clinical presentation of pre-

viously undiagnosed ET, with positive Janus kinase 2

(JAK2) V617F gene mutation.

Case discussion

A 68-year-old Caucasian man with no significant

past medical history presented to the emergency

room reporting chest pain. His symptoms of severe,

crushing, non-radiating, and retrosternal chest pain

started 2 hours before he came to the emergency

room. He reported no history of cardiac problems,

was not taking any cardiac medications, and had no

family history suggesting any cardiac diseases.

Physical examination revealed moderate distress

and diaphoresis. His pulse was 88 beats per minute,

his blood pressure was 128/84 mm Hg, and his

respiratory rate was 18 breaths per minute with 98%

oxygen saturation on room air. Auscultation revealed

normal S1 and S2 heart sounds with no murmur or

gallop. His chest was clear to auscultation on both

sides. Cardiac markers suggested cardiac ischemia;

troponin I peaked at 3.13 ng/ml. He had thrombo-

cytosis at the time of admission (platelet

count¼ 539� 103/l). Other laboratory values were

Correspondence: Anand Singla, Fellow, Cardiovascular Diseases, Department of Cardiology, Guthrie Clinic/Robert Packer Hospital, One Guthrie

Square, Sayre, PA 18840, USA. Tel: 570-882-2331. Fax: 570-887-2290. E-mail: anand_ucms@yahoo.co.in

(received 5 October 2011; revised 28 October 2011; accepted 9 November 2011)

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white blood cell count, 7.48� 103/ml; hematocrit,

36.8%; calcium, 9.6 mg/dl; potassium, 4.0 mEq/l;

and creatinine, 0.63 mg/dl. Liver function test results

were normal.

A 12-lead electrocardiograph showed sinus

rhythm with 1–2 mm ST-segment elevation in

inferior leads; II, III, and AVF. Prominent T waves

were also noted in precordial leads (Figure 1). Acute

STEMI was diagnosed and subsequent coronary

angiography revealed isolated significant narrowing

of proximal left anterior descending coronary artery

with haziness suggestive of thrombus (Figure 2A).

Percutaneous aspiration thrombectomy was per-

formed using Export catheter and a blood clot was

confirmed in the catheter after aspiration. A TIMI

grade 3 Fow was obtained. After thrombectomy,

left anterior descending coronary artery did not

reveal any stenosis (Figure 2B). The remainder

of the coronary vasculature was also normal with

no atherosclerosis. The possibility of right coronary

artery thrombus with spontaneous thrombolysis

could not be excluded to explain ischemic changes

in inferior leads on a 12-lead electrocardiogram.

The patient was treated with GpIIb-IIIa inhibitor,

eptifibatide, and monitored in intensive care unit.

The patient showed significant recovery over the next

3 days of hospitalization and was discharged in a

stable condition. His discharge medication included

antiplatelet agents, aspirin 325 mg daily, and clopi-

dogrel 75 mg daily.

During hospitalization, secondary causes for

intracoronary thrombus were evaluated due to the

absence of conventional risk factors for CAD and

normal coronary anatomy with no atherosclerotic

Figure 2. (A) Cardiac catheterization revealed proximal left anterior descending coronary artery haziness suggestive of thrombus.

A magnified view of intracoronary thrombus is shown in box. (B) Left anterior descending coronary artery after percutaneous coronary

intervention with aspiration thrombectomy with no underlying obstructive atherosclerotic disease.

Figure 1. A 12-lead electrocardiogram showed sinus rhythm with 1–2 mm ST-segment elevation in inferior leads. Prominent T waves were

also noted in precordial leads.

464 A. Singla et al.

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lesions after the thrombus was removed.

Transthoracic echocardiogram did not reveal any

evidence of intracardiac thrombus. Left ventricular

systolic function was within normal limits with no

wall motion abnormalities. The possibility of para-

doxical embolization with patent foramen ovale was

ruled out with negative bubble study on transthoracic

echocardiogram. Investigations for hypercoagulabil-

ity demonstrated a heterozygous mutation for

Factor V Leiden, otherwise a normal profile includ-

ing Anti thrombin III, lupus anticoagulant, antic-

ardiolipin antibody, protein C, protein S, and

prothrombin mutation. The platelet counts remained

high while in hospital.

During follow-up visit as outpatient at 1 month,

our patient showed persistent elevation of platelet

count with one episode of platelet count more than

600� 103/l. A possible diagnosis of ET was con-

sidered. Genetic studies were positive for the JAK2

V617F gene mutation. As our patient had high risk

factors for thrombotic complications, treatment

with cytoreductive therapy using hydroxyurea was

instituted to lower the platelet count though our

patient was asymptomatic. Six months after his index

hospitalization, patient continues to do well with

no further thrombotic or hemorrhagic complications.

Discussion

Normal coronary angiogram in patients with AMI is

not a rare presentation, and accounts for 3% of the

total cases [5]. Multiple etiological factors have been

reported including coronary spasm, coagulation

disorders, collagen vascular diseases, embolization,

and oral contraceptive use [6]. In our case, ET with

JAK2 V617F mutation initially presented with

acute STEMI secondary to intracoronary thrombus

formation, otherwise normal coronary arteries, and

required percutaneous thrombectomy with success-

ful revascularization.

ET is a myeloproliferative clonal disorder result-

ing from the transformation of pluripotent hemato-

poietic cells [1, 2]. The incidence rate for ET is

2.5 cases per 100� 103 populations per year [7].

Approximately, half of the patients diagnosed with

ET are asymptomatic and others commonly have

vasomotor symptoms. However, ET is associated

with increased risk for thrombotic and hemorrhagic

complications causing significant morbidity and

mortality. Both thrombosis and hemorrhage result

from qualitative and quantitative defects of the

platelets [8]. After the initial diagnosis of ET,

a total of 7–17% thrombotic event rates have been

reported over a follow-up period of 3–7 years [9, 10].

Thrombotic complications included both arterial and

venous events; stroke, transient ischemic attacks,

retinal artery or venous occlusions, coronary artery

ischemia, pulmonary embolism, hepatic or portal

vein thrombosis, deep vein thrombosis, and digital

ischemia.

The association of coronary thrombotic events

with ET is well established [11–14]. In the last two

decades, multiple risk factors have been identified

to predict ET-related thrombotic complications.

Age more than 60, previous history of thrombotic

complications, and platelet count41500� 109/l were

reported as high risk factors for thrombotic compli-

cations [15]. Hydroxyurea is the treatment of choice

to prevent thrombotic events in ET for high-risk

individuals with age460 [16]. De Stefano et al. [17]

demonstrated a significant reduction of 70% in

recurrent thrombotic events in patients with poly-

cythemia vera or ET who had acute coronary

syndrome as the index thrombosis. Furthermore,

the contemporary use of an antiplatelet agent with

cytoreductive therapy showed enhanced efficacy

in preventing re-thrombosis. Though in this case,

patient had platelet counts less than 600� 109/l,

treatment with hydroxyurea was instituted in addi-

tion to an antiplatelet agent (aspirin 81 mg daily) with

history of recent coronary thrombotic event and age

factor. There are several reports of complications at

platelet counts lower than 600� 109/l in patients

diagnosed with ET. In a report by Regev et al. [18],

severe thrombotic complications were reported at

platelet counts lower than 600� 109/l in sympto-

matic patients with ET. It was recommended that

symptomatic patients with ET and relatively low

platelet counts should be treated with target platelet

counts well into the lower normal range.

The JAK2 somatic mutation is closely related to

chronic myeloproliferative disorders and more than

half of individuals with ET exhibit JAK2 V617F

mutation [19]. However, JAK2 V617F-mutated

patients are not predisposed to increased incidence

of thrombotic events relative to JAK2 wild type [15].

Furthermore, increased sensitivity to cytoreductive

therapy using hydroxyurea has been reported in

this group [19]. In our case, positive JAK2 V617F

mutation confirmed the diagnosis for ET after the

initial presentation with acute STEMI. Our patient

was also reported to have Factor V heterozygous

mutation, known to be associated with a 3–6-fold

increase in the risk of venous thrombosis [20]. There

is no association of Factor V heterozygous mutation

with arterial thrombosis. Multiple studies have

concluded that patients with this mutation alone do

not have increased risk of AMI or stroke [21].

Factor V heterozygous mutation is not an uncom-

mon pathology with prevalence rate of 4–6% in

general population [20, 22]. We believe that this

finding in our case is incidental in nature and

unrelated to current presentation.

Acute ST-segment elevation myocardial infarction 465

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Conclusions

Our case describes a rare initial presentation of

previously undiagnosed ET with acute STEMI.

It highlights the importance of secondary workup

for STEMI with isolated intracoronary thrombus

otherwise normal coronary vasculature with no focal

atherosclerosis. Though a rare cause, ET should

be considered as a differential for a patient

presenting with persistently elevated platelet count

and a thrombus in a patent coronary artery.

Declaration of interest: There are no potential

conflicts of interest to be disclosed.

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