hypertrophic cardiomyopathy ( hcm ) is a genetically heterogeneous heart muscle disorder characterized by myocardial hypertrophy in the absence of abnormal loading conditions .
while it has been recognized for many decades that some patients with the disease die suddenly from ventricular arrhythmia , data from contemporary studies suggest that the annual risk of sudden cardiac death ( scd ) is in the range of 1% .
some risk factors have been shown to be associated with an increased risk of scd in patients with hcm .
the challenge for clinicians is to identify the small cohort of patients who are at a higher risk in order to target potentially lifesaving therapy such as implantable cardioverter defibrillators ( icd ) .
fragmented surface electrocardiogram ( ecg fqrs ) has been identified as a useful risk marker in other clinical conditions ; however , its use in arrhythmic events in patients with hcm has not been suggested .
we report a case of an 18-year - old girl with hcm and aborted scd and implanted with an icd .
her surface 12-lead ecg evolved from normal to fqrs complex in less than 7 years . during a 2-year follow - up ,
she presented with recurrent syncope . at that time , her 12-lead electrocardiogram ( ecg ) showed sinus rhythm , q - waves and negative t - waves in leads v5 and v6 with a qrs duration < 120 ms . [ figure 1 , left panel ] .
her echocardiogram depicted an asymmetrical left ventricular hypertrophy with an interventricular septum measuring 22 mm and no intraventricular gradient . during the screening ,
secondary causes of left ventricular hypertrophy such as systemic hypertension , congenital disease and valvular diseases were ruled out .
her first degree relatives were screened with ecg and echocardiogram , however , no phenotypic hcm was found .
the patient remained asymptomatic under treatment with atenolol 50 mg / day for 7 years , when she suffered a cardiac arrest following an episode of emotional stress .
ventricular fibrillation ( vf ) was detected and terminated by an external electrical shock . during hospitalization ,
an echocardiogram showed massive left and right ventricular hypertrophy with a septal thickness of 38 mm and absence of intraventricular gradient [ figure 2 ] .
the surface 12 lead ecg showed q - waves in leads i , avl , v5 , v6 , left ventricular strain pattern , inverted t - waves , and a qrs duration of 130 ms with fqrs in all leads .
[ figure 1 , right panel ] a dual chamber icd ( maximo dr 7278 , medtronic , inc , mn , usa ) was implanted .
the patient was discharged and treated with atenolol 50 mg twice a day . during the two - year follow - up ,
anti - tachycardia pacing was effective in numerous occasions to convert vt into a normal sinus rhythm ; however , on 2 occasions , shocks were necessary to resolve the arrhythmia .
atenolol dose was increased and the patient has remained asymptomatic since the last six months . in the left panels , 12-lead electrocardiogram ( ecg)at the age of nine ( 2002 ) , depicting sinus rhythm , pr interval 160 ms , qtc 380 ms and q - waves in leads v5 , v6 with negative t - waves . in the right panel , 12-lead ecg on admission at the age of sixteen ( 2009 ) , depicting sinus rhythm ; pr interval 130 ms and delayed left atrial depolarization ( the second vector of the p - wave is delayed , most likely by fibrosis of the interatrial septum ) ; deep q - waves in leads i , avl , v5 , and v6 , diffuse t - wave inversion , qrs duration 130 ms and different morphologies of fqrs , including various rsr  patterns parasternal large axis view ( left ) and apical four - chamber view ( right ) depicting global thickened of the left ventricular walls and right ventricle and interatrial septum involvement .
ivs : interventricular septum ; la : left atria ; lv : left ventricle ; ra : right atria ; rv : right ventricle
the stratification of risk in hcm in clinically stable patients is predicated on generally accepted noninvasive markers .
the accepted risk factors in hcm include family history of  1 hcm - related scds ,  1 episode of unexplained syncope , massive left ventricular ( lv ) hypertrophy ( thickness  30 mm ) ; nonsustained vt on serial ambulatory 24-hour holter , and hypotensive or attenuated blood pressure response to exercise .
the ecg has traditionally been a part of the non - invasive evaluation for patients with hcm and though various electrocardiographic abnormalities were described , most of them correlated with the magnitude and extent of ventricular hypertrophy ; however , did not reflecte increased risk per se .
some investigators have attributed the disturbed myocardial electrical properties in hcm to the distinctive anatomical substrate of hypertrophied and disorganized myocytes .
indeed , ventricular electrogram fractionation ( delayed myocardial activation ) has been documented by programmed ventricular extrastimulation in patients with hcm and induced vf ; however , was absent in patients without vf . recently ,
das et al . described the presence of fqrs in patients with coronary artery disease ( cad ) .
the fqrs was defined in the 12-lead ecg as the presence of an additional r - wave ( r ) or notching in the nadir of the r - wave or the s - wave , or the presence of > 1 r ( fragmentation ) in 2 contiguous leads , corresponding to a major coronary artery territory .
fragmented qrs in the presence of wide qrs complexes (  120 ms ) , such as bundle branch block ( bbb ) , premature ventricular complexes ( pvcs ) and paced qrs complexes ( pqrs ) , was defined by the presence > 2 notches in the r - wave or the s - wave , since bbb already have two notches or peaks present in two contiguous leads ( 3 ) .
fqrs has been associated with inhomogeneous activation of the ventricles due to myocardial scar and/or ischemia , which could predict arrhythmic events as well as death .
the underlying mechanisms of fragmentation have been supported by autopsy studies of patients with myocardial infarction ( mi ) and left ventricular aneurysm .
these studies showed that the presence of fqrs was associated with a significant myocardial necrosis alternating with viable myocardial tissue and interspersed in abundant fibrous tissue .
distribution and pattern of the scar depends on the disease states . in cad , myocardial scars are segmental and subendocardial or transmural , whereas in nonischemic cardiomyopathy the scars are patchy and mid myocardial or subepicardial , predominantly in the perivalvular areas . in the presented case ,
myocardial scars are probably the cause of localized conduction block leading to an additional r  or notching of the r  wave or s - wave .
endocardial and epicardial mapping in patients with cad or dilated cardiomyopathy with ventricular arrhythmias have revealed fractionated electrograms over a wide area surrounding the myocardial scar .
fqrs is not specific for cad , and was also observed in other myocardial diseases such as dilated cardiomyopathy , some congenital heart diseases , arrhythmogenic right ventricular cardiomyopathy and brugada syndrome . to the best of our knowledge ,
this is the first report of a patient with hcm and rapidly progressive fqrs , with documented malignant ventricular arrhythmias treated by an icd .
the progressive fragmentation of the qrs and the presence of malignant ventricular arrhythmias , lead us to speculate on the value of fqrs as a predictor of ventricular arrhythmias in patients with hcm .
, in a long series of 330 patients with hcm and high - risk criteria of scd with icd implantation , compared the relationship of electrocardiographic findings and appropriate icd therapies . during a follow - up of 3.7  3.0 years , 17% of the patients had appropriate icd discharges .
the authors found no distinctive ecg characteristics in patients with and without appropriate icd interventions .
bongioanni et al . found in 241 patients with hcm that a qrs duration  120 ms had an odds ratio of 5.2 for all - cause cardiovascular death ; however , was not found to predict scd .
hypothetically , the lack of correlation of malignant ventricular arrhythmias with ecg abnormalities supports the notion that scd likely depends on transient electrophysiologic status and by interacting with the underlying substrate , such as vascular ischemia , neuroendocrine or electrolyte imbalance .
such transient injuries are consistent with the unpredictable nature of hcm - related scd that may occur years after diagnosis , and often without any warning . in the presented case ,
the fqrs probably reflects a more severe myocardial disease , manifested by severe progression of ventricular hypertrophy .
fqrs should be investigated in larger series of patients as a possible new risk factor and predictor of arrhythmic events in patients with hcm .
fqrs should be tested in a larger series of patients as a possible new risk factor and predictor of arrhythmic events in patients with hcm .
 an 18- year old woman with hypertrophic cardiomyopathy , aborted sudden cardiac death and implanted with an implantable cardioverter defibrillator ( icd ) , developed progressive fragmentation of her surface 12-lead electrocardiogram ( ecg ) . during the follow - up , she presented with multiple appropriate icd discharges . here , we discuss the possible association between surface fragmented ecg and the risk of ventricular arrhythmias in patients with hypertrophic cardiomyopathy . 