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Kearns-Sayre syndrome (KSS) is a rare multi-

system mitochondrial disorder associated with the

phenotypic triad of progressive external oph-

thalmoplegia, atypical pigmentary degeneration

of the retina, and complete heart block. Other

features include sensorineural deafness, impaired

intellectual function, short stature, and endocrine

and renal abnormalities, which usually present

before the age of 20.1-3 Diagnostic tools have not

been definitively established, but physicians have

diagnosed KSS based on many modalities includ-

ing laboratory findings, electrocardiogram

(ECG),4 clinical manifestations, and muscle

biopsy.5

In this report, we describe a patient with type

I diabetes and KSS who experienced syncope in

the presence of complete atrioventricular (AV)

block.

CASE

A 16-year-old boy was first seen in the emer-

gency department with an episode of loss of

consciousness. His parents reported that it was

the first such episode, no premonitory symptoms

had been observed, and there was no notable fam-

ily history.

Physical examination revealed no abnormality

and stable vital signs (blood pressure: 110/70

mmHg, respiratory rate: 18 breaths per minute,

body temperature: 36.2°C), but the patient’s ECG

Kosin Medical Journal 2017;32:133-138.https://doi.org/10.7180/kmj.2017.32.1.133 KMJ

Case Report

Kearns-sayre Syndrome Treated with Permanent Pacemaker Insertion for Complete Atrioventricular Block

Eun Hye Park, Sung Ho Her, Myung A Ha, Hyo Suk Kim, Jae Hyuk Jang

Division of Cardiology, College of Medicine, the Catholic University of Korea, Seoul, Korea

Kearns-Sayre syndrome (KSS) is a rare multisystem mitochondrial disorder associated with progressive external ophthalmoplegia, atypical pigmentary degeneration of the retina, and complete heart block. KSS can lead

to a risk of sudden death because of the potential progression of conduction abnormalities such as right or left bundle branch block or complete atrioventricular (AV) block. Here we describe the case of a KSS patient with type I diabetes who experienced syncope in the presence of complete AV block, confirmed by muscular

biopsy.

Key Words: Complete AV block, Kearns-Sayre syndrome, Permanent pacemaker

Corresponding Author: Sung Ho Her, Daejeon St. Mary’s hospital, 642 Daeheung-ro, Jung-gu,

Daejeon 34943, Korea

Tel: +82-042-220-9504 Fax: +82-042-226-9686 E-mail: hhhsungho@naver.com

Received:Revised:Accepted:

May. 13, 2016Jul. 07, 2016Jul. 25, 2016

Kosin Medical Journal 2017;32:133-138.

134

revealed complete AV block with a wide QRS (150

ms), ventricular rhythm was 34 beats per minute,

and corrected QT interval was 378 ms (Fig. 1A)

Therefore, we performed temporary pacemaker

insertion. We observed patients in the intensive

care unit (ICU) under continuous ECG monitoring

without Holter monitoring.

The patient had been of short stature since

childhood and did not like to exercise because

of easy fatigue. At 4 years old, exotropia levator

Fig. 1. ECG revealed complete atrioventricular block with a wide QRS (150 ms) and ventricular rhythm of 34 beats per minute (bpm) (A), normal finding at 9 years old (B), and pacemaker rhythm(DDDR type). (C).

Kearns-sayre Syndrome with Complete Atrioventricular Block

135

resection and lateral rectus resection were per-

formed to repair what had been considered con-

genital ptosis. Additionally, median rectus re-

section was performed when the patient was 10

years old due to subsequent recurrent exotropia.

There was no abnormality of the ECG at that time

(Fig. 1B). He was diagnosed with type I diabetes

and started insulin therapy at 15 years of age. At

that time, the HbA1c level was 10.1%, and serum

C-peptide levels were 0.221 ng/㎎ (fasting) and

1.19 ng/㎎ (postprandial).

At this time, CBC and ESR were within the normal

ranges for the patient’s age and sex. Serum lactate

(25.2 ㎎/dl) and myoglobulin levels (150.6 ng/ml)

were elevated. Liver function test showed mild ele-

vation, with elevated AST (63 IU/L) and ALT (43

IU/L). Muscle enzymes lactate dehydrogenase (754

IU/L) and creatine phosphokinase (1139 IU/L) were

also elevated. Other laboratory findings such as

BUN (13.1 ㎎/dl), creatinine (0.93 ㎎/dl), Na (141

mEq/L), K (3.4 mEq/L), Ca (8.8 ㎎/dl), and Mg (2.0

㎎/dl) were normal. Thyroid function test was also

normal. Left ventricular ejection fraction was

61.1% without regional wall motion abnormality

on echocardiography.

On ophthalmoscopy to discriminate KSS, the

fundus showed atypical retinal pigmentary degen-

eration (Fig. 2). We impressed mitochondrial

myopathy, and biopsy of the right thigh muscle

(medial side) was performed. Unexpectedly, on

light microscopic examination, modified tri-

chrome stain revealed no diagnostic abnormal-

ities such as ragged red fibers. Other enzyme his-

tochemical and immunohistochemical stains

were unremarkable (Fig. 3A), but electron micro-

scopic examination, which is generally consid-

ered a more precise examination for mitochon-

dria, revealed muscle cells with subsarcolemmal

collections of mitochondria, many of them con-

taining crystalline inclusions, electron micro-

scopically consistent with mitochondrial myo-

pathy (Fig. 3B).

Fig. 2. Ophthalmoscopy of the fundus showed atypical retinal pigmentary degeneration (salt and pepper retinitis) (red arrow).

Kosin Medical Journal 2017;32:133-138.

136

After 3 days, ECG showed no recovery of normal

sinus rhythm and persistent complete AV block,

so we inserted a permanent pacemaker (DDDR

type) (Fig. 1C). Cardiac MRI performed to exclude

structural abnormalities before permanent pace-

maker insertion showed normal cardiac chamber

size and myocardial wall thickness and no my-

ocardial delayed hyperenhancement, structural

abnormality, or myocardial infiltrative disease.

We finally diagnosed Kearns-Sayre syndrome

based on clinical manifestation, laboratory find-

ings, and pathological confirmation.

DISCUSSION

Kearns-Sayre syndrome (KSS) has become rec-

ognized as a disease entity comprised of a con-

stellation of features including progressive ex-

ternal ophthalmoplegia, pigmentary retinopathy,

cardiac conduction system disorder, and multiple

endocrine disorders.3

Muscle biopsy can confirm the diagnosis based

on cytochrome C oxidase-negative ragged red fi-

bers on modified Gomori stain. Electron micro-

scopy reveals subsarcolemmal accumulation of

Fig. 3 Light and electron microscopic examination of the right thigh muscle Modified trichrome stain revealed no diagnostic abnormalities such as ragged red fibers, similar to other enzyme histochemical and immunohistochemical stains (A, LM finding), but showed muscle cells with subsarcolemmal collection of mitochondria, many of them containing crystalline inclusions (red arrow), electron microscopically consistent with mitochondrial myopathy (B, EM finding).

Kearns-sayre Syndrome with Complete Atrioventricular Block

137

abnormal mitochondria with paracrystalline in-

clusion bodies, and a more definite diagnosis

based on mitochondrial DNA deletions de-

termined by Southern blot or polymerase chain

reaction should be sought.6

Our patient had several characteristic features

of KSS, including progressive external oph-

thalmoplegia, retinal pigmentation, so-called

“salt and pepper retinitis”, ptosis, muscle weak-

ness, and mild cognitive disorders as well as type

I diabetes (reported to affect 10% of KSS

patients.3), metabolic acidosis, and high levels of

lactate and creatine kinase. Of these, the cardiac

manifestations, which create various degrees of

AV block through the His-Purkinje system, are the

most important factor for determining the prog-

nosis of the disease.

In some rare cases, KSS has been diagnosed af-

ter death due to cardiac arrest. Most KSS patients

have been diagnosed in Europe, the Middle East,

and North America.4-7 In Korea, one case involv-

ing the cardiac conduction system has been

reported. That patient had a permanent pace-

maker implanted, but the diagnosis was not con-

firmed by muscle biopsy.8

Our patient’s diagnosis of KSS involving the car-

diac conduction system was confirmed by muscle

biopsy, which is rarely performed in Korea. In

this case, we aimed to prevent sudden cardiac ar-

rest by implanting a pacemaker at an early stage

in patients who had specific ECG findings and it

is meaningful to make follow up the KSS.

When we saw the KSS patients, we could detect

right or left bundle branch block or complete AV

block on ECG, Prophylactic pacemaker therapy

is advisable in these patients because of the po-

tential for progression of conduction abnormal-

ities and risk of sudden death.

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