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DOI: 10.1161/CIRCULATIONAHA.106.623934 2006;113;e753-e756 Circulation

Shlomo Stern Electrocardiogram: Still the Cardiologist’s Best Friend

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ElectrocardiogramStill the Cardiologist’s Best FriendShlomo Stern, MD

Case presentation: A 22-year-old male, previously healthy,came to the outpatient clinic

soon after an episode that he describedas “near fainting” during completerest, but at the time he was feelingstrong anger because of a dispute withhis friends. The physical examinationwas normal, but the resting 12-leadECG, taken for the first time in his life,showed alterations diagnosed as Bru-gada syndrome (Figure). Holter moni-toring showed the typical signs of thesyndrome with no other abnormalities.The patient was referred for furtherevaluation, including family search forthis syndrome, which turned out neg-ative. Currently, implantation of animplantable cardioverter-defibrillatoris being considered in a tertiary hospi-tal for this patient.

BackgroundIn the last several years, we have seena new surge of interest in electrocardi-ology.1 In the following report, wedescribe innovations in interpreting the12-lead ECG in the physician’s officethat contribute to an instant diagnosisand to practical conclusions in ourday-to-day clinical practice.

Patients at High Risk forSudden Cardiac Death

Although �90% of cases of suddencardiac death (SCD) occurs in personswithout known or previously recog-nized structural or functional cardiacabnormalities, scrutinizing the QRSvoltage, as well as the QT and cor-rected QT (QTc) intervals of the sur-face ECG, will help in diagnosing riskfactors for SCD. A QTc �450 ms formen and �470 ms for women was anindependent risk factor for SCD insubjects enrolled in the RotterdamStudy aged �55 years; a 3-fold in-creased risk of SCD after adjustmentfor other risk factors was found inthese patients.2 An increased QRSvoltage was found to increase the riskfor out-of-hospital cardiac arrest inwomen but not in men in the Reykja-vik Study.3 In patients in whom coro-nary artery disease is suspected, thepresence of isolated left anterior hemi-block represents an increased risk forarrhythmic cardiac death.4

Patients Resuscitated FromCardiac Arrest

Patients resuscitated from cardiac arrestdue to ventricular tachyarrhythmia with-out clear precipitating factors are at highrisk of recurrence, and therefore long-term prophylactic therapy is indicated.

Wever and Robles de Medina5 pointedout that in contrast to older beliefs, sur-vivors of idiopathic ventricular fibrilla-tion are currently also considered high-risk patients, because the recurrence rateof life-threatening episodes was as highas 43% after an average of �6 years offollow-up.

Wolff-Parkinson-WhiteSyndrome

Wolff-Parkinson-White syndrome inmany cases shows preexcitation on thesurface ECG. These patients have arisk of SCD �1 per 1000 patient-yearsof follow-up. Almost all survivors ofSCD with Wolff-Parkinson-Whitesyndrome have had symptomatic ar-rhythmias before the event, but up to10% experience SCD as their firstmanifestation of the disease.6

Arrhythmogenic RightVentricular Dysplasia

The diagnostic ECG marker for ar-rhythmogenic right ventricular dyspla-sia is, in the absence of right bundle-branch block, an S-wave upstroke �55ms in V1 through V3, which correlateswell with disease severity and subse-quent induction of ventriculartachycardia on electrophysiologicalstudy.7 These patients have spontane-ously abnormal ECGs in 83.9% of

From the Hebrew University of Jerusalem, Jerusalem, Israel.Correspondence to Dr Shlomo Stern, FAHA, 1 Shmuel Hanagid St, Jerusalem 94592, Israel. E-mail sh_stern@netvision.net.il(Circulation. 2006;113:e753-e756.)© 2006 American Heart Association, Inc.

Circulation is available at http://www.circulationaha.org DOI: 10.1161/CIRCULATIONAHA.106.623934

CLINICIAN UPDATECLINICIAN UPDATE

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cases.8 The authors studied 130 pa-tients with a mean follow-up of 8.1years, during which 24 deaths wererecorded. All patients who died had ahistory of ventricular tachycardia.Multivariate analysis showed that afteradjustment for gender, history of syn-cope, chest pain, inaugural ventriculartachycardia, recurrence of ventriculartachycardia, and QRS dispersion, clin-ical signs of right ventricular failureand left ventricular dysfunction bothremained independently associatedwith mortality. The syndrome is pro-gressive, and within 6 years of presen-tation, nearly all patients had an abnor-mal finding on their surface ECG.

Prolonged QTc IntervalA prolonged QTc interval was associ-ated with an increased risk of coronaryheart disease and cardiac mortality inboth black and white healthy men andwomen.9 A prolonged QTc was asso-ciated in the Atherosclerosis Risk InCommunities (ARIC) Study with thepresence of ECG abnormalities, possi-bly resulting from small, silent myo-cardial infarctions. These authorsviewed a prolonged QTc as a markerof subclinical atherosclerosis. Twothirds of the cases of SCD were asso-ciated with an abnormal prolongationof the QTc interval. This investigationshowed that in individuals with bor-derline and abnormally prolonged QTcduration, a dose-response effect ex-isted between the duration of the QTcinterval and the risk of SCD in the agegroups of 55 to 68 years and �68years, separately for men and women,after adjustments for relevant covari-ates. In view of knowledge about the

QT-prolonging properties of variousimportant antiarrhythmic drugs andgiven that the administration of severalof these drugs is associated with anincreased mortality,10 meticulous clin-ical and ECG follow-up of such pa-tients is mandatory.

Short QTc IntervalA short QTc interval, �300 ms, diag-nosed on the 12-lead ECG became arelatively new clinical entity called the“short-QT syndrome,” characterizedby the absence of structural heart dis-ease, a family history of SCD, andmajor or minor arrhythmic events.11

This syndrome was shown to be afamilial cause of sudden death, and theimportance of recognizing this ECGpattern even in young, otherwisehealthy subjects was stressed by Gaitaand coworkers.12

Brugada SyndromeThe Brugada syndrome, an arrhythmo-genic disorder associated with a highrisk of SCD due to ventriculartachycardia/fibrillation, is diagnosedon the 12-lead ECG by a pattern ofright bundle-branch block and a coved,�2-mm ST-segment elevation in leadsV1 through V3. In patients withBrugada-type ECG and no history ofcardiac arrest, among 12 noninvasiverisk indices in multivariate analysis,spontaneous changes in the ST seg-ment were found to be the most signif-icant predictor of subsequent suddendeath or ventricular tachyarrhythmiaduring a 40�19-month follow-up.13

However, because ST-segment eleva-tion is associated with a wide varietyof benign and malignant pathophysio-

logical conditions, a differential diag-nosis is difficult at times.14

Noncardiac SurgeryCandidates

Noncardiac surgery candidates withcoronary artery disease need preoper-ative evaluation, which should cer-tainly include a 12-lead ECG. Theprognostic information available froman ECG was studied by Jeger andcoworkers.15 After adjustment for clin-ical baseline findings, ST depressionand faster heart rates were independentpredictors of all-cause mortality.Faster heart rate was also an indepen-dent predictor of major adverse cardiacevents at 2 years. The predictive valueof the ECG was independent of clini-cal findings and perioperativeischemia.

Asymptomatic IndividualsWhen asymptomatic individuals, suchas those included in the CopenhagenCity Heart Study,16 presented with leftventricular hypertrophy with ST de-pression and negative T waves in theirECG, they had an age-adjusted relativerisk of 3.78 for myocardial infarction,4.27 for ischemic heart disease, and3.75 for cardiovascular disease duringa 7-year follow-up. Given these re-sults, our European colleagues con-cluded that in asymptomatic individu-als, ECG findings should be treated“on an equal footing” with the classicrisk factors and can be involved in riskassessment.17

Female PatientsIn female patients, the value of theECG for risk stratification was similar

Twelve-lead ECG of the patient showing typical changes for Brugada syndrome.

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to that in males, in contrast to thewidespread misconception that theECG is of limited utility in women.18

Rautaharju and coworkers19 studied 5ECG variables in men and women andfound them to be equally significantmortality predictors in both genders.

Unrecognized MyocardialInfarction

Unrecognized myocardial infarction inmen carries a substantially increasedcoronary risk, and its diagnosis in theoffice is therefore of high importance.The determination of optimal ECGcriteria for this retrospective diagnosiswas the subject of several studies.Ammar and coworkers20 scrutinized 6different surveys and described a highspecificity for ECG criteria (91.9% to97.5%) in all studies but a low sensi-tivity (20.8% to 29.7%); even the Brit-ish Regional Heart Study21 provided asensitivity of only 37%. In this laststudy, a somewhat better prognosiswas found for men with unrecognizedinfarctions than for those with recog-nized infarctions: Adjusted to an aver-age age of 50 years, the percentage ofmen surviving for 15 years free of anew major cardiovascular event was52% for the former and 44% for thelatter group.

Post-Myocardial InfarctionPatients

After reperfusion/revascularizationtherapy, post-myocardial infarction pa-tients who had a prolonged QRS dura-tion (�120 ms) showed on multivari-able analysis the highest associationwith total mortality (hazard ratio 4.0,95% confidence interval 2.3 to 6.9).22

The association of prolonged QRS du-ration and late mortality was particu-larly strong in patients with left ven-tricular ejection fraction �30%.

Cardiac ResynchronizationTherapy

Optimal candidates for CRT are thepatients with a QRS complex duration�120 ms, dilated cardiomyopathy onan ischemic or nonischemic basis, leftventricular ejection fraction �0.35,

New York Heart Association func-tional class III or IV despite maximalmedical therapy for heart failure, andsinus rhythm.23 Even the success ofcardiac resynchronization therapy canbe evaluated by measuring the QRScomplex. Among multiple demo-graphic, clinical, and ECG variables,the amount of QRS shortening associ-ated with biventricular simulation wasthe only independent predictor of agood clinical response, as demon-strated by Lecoq and coworkers.24

Heart FailureHF is frequently associated with aprolongation of the QRS complex be-yond 120 ms, an abnormality observedin 14% to 47% of the patients in thestudy by Kashani and Barold.25 Left-sided intraventricular conduction delaypredisposed patients to an increasedrisk of tachyarrhythmias and was asso-ciated with more advanced myocardialdisease, worse left ventricular func-tion, poorer prognosis, and a higherall-cause mortality rate. A graded in-crease in mortality was observed withthe width of the QRS complex, and aQRS �120 ms, QRS 120 to 160 ms,and QRS �160 ms correlated with20%, 36%, and 58% mortality, respec-tively, at 36 months.26 The mean QRScomplex amplitudes and the sum of allQRS complex amplitudes were foundto be “unique” for predicting the resultof a positive versus negative dobuta-mine stress echocardiogram in patientswith ischemic left ventriculardysfunction.27

In patients with chronic HF, a QRSduration �140 ms was associated witha 60% event-free survival rate versus90% among those with a QRS duration�144 ms. This ECG parameter wascomplementary to further echocardio-graphic assessment of these patients.28

The ECG and �-type natriureticpeptide were evaluated as screeningtools for left ventricular systolic dys-function in a random elderly popula-tion.29 For ECG alone, sensitivity,specificity, and negative and positivepredictive values to detect left ventric-

ular systolic dysfunction were 96%,79%, 100%, and 26%, respectively.

Hypertensive PatientsIn hypertensive patients, a strain pat-tern, defined as a down-sloping convexST segment with inverted asymmetri-cal T-wave opposite the QRS axis inlead V5 or V6, identified an increasedrisk of developing HF and of dying asa result of HF. This was found even inthe setting of aggressive blood pres-sure lowering, which suggests thatmore aggressive therapy may be war-ranted in hypertensive patients withECG strain to reduce the risk of HFand HF mortality.30 ECG follow-up inpatients with ECG evidence of leftventricular hypertrophy showed that areduction in the left ventricular hyper-trophy criteria, using the Cornellvoltage-duration product and/orSokolow-Lyon criteria, was associatedwith a reduced likelihood of cardiovas-cular events.31

ConclusionsThe 12-lead surface ECG can indicatepathological changes even beforestructural changes in the heart can bediagnosed by other methods. The re-cording of an ECG was of great valuefor several past generations of cardiol-ogists and continues to provide vitalinformation. Researchers should fur-ther scrutinize Einthoven’s ingeniousmethod, and clinicians should continueto tap this important and reliablesource of information.

AcknowledgmentsI wish to thank Professor Shmuel Gottliebfor allowing me to publish the case study ofthe patient described. The excellent edito-rial help of Liane Herman is gratefullyappreciated.

DisclosuresNone.

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