Catheter ablation of atrial fibrillation in Korea: results from the Korean Heart Rhythm Society Ablation Registry for Atrial Fibrillation (KARA)

Background@#This study aims to investigate the current status of AF (atrial fibrillation) catheter ablation in Korea. @*Methods@#The patients who underwent AF catheter ablation from September 2017 to December 2019 were pro‑ spectively enrolled from 37 arrhythmia centers. Demographic data, procedural characteristics, the extent of catheter ablation, acute success of the ablation lesion set, rate and independent risk factor for recurrence of AF were analyzed. @*Results@#A total of 2402 AF patients [paroxysmal AF (PAF) 45.7%, persistent AF (PeAF) 43.1% and redo AF 11.2%] were included. Pulmonary vein isolation (PVI) was performed in 2378 patients (99%) and acute success rate was 97.9%.Additional non-PV ablation (NPVA) were performed in 1648 patients (68.6%). Post-procedural complication rate was 2.2%. One-year AF-free survival rate was 78.6% and the PeAF patients showed poorer survival rate than the ones with other types (PeAF 72.4%, PAF 84.2%, redo AF 80.0%). Additional NPVA did not influence the recurrence of AF in the PAF patients (PVI 17.0% vs. NPVA 14.6%, P value 0.302). However, it showed lower AF recurrence rate in the PeAF patients (PVI 34.9% vs. NPVA 24.4%, P value 0.001). Valvular heart disease, left atrial diameter, PeAF, PVI alone, need of NPVA for terminating AF, and failed ablation were independent predictors of AF recurrence. @*Conclusions@#Additional NPVA was associated better rhythm outcome in the patients with PeAF, not in the ones with PAF. The independent risk factors for AF recurrence in Korean population were similar to previous studies. Further research is needed to discover optimal AF ablation strategy.

Design of Korean Noninvasive Risk Evaluation Study for Sudden Cardiac Death from Infarction or Heart Failure: Myocardial infarction study of K-REDEFINE registry

BACKGROUND AND OBJECTIVES: Despite significant advances in the treatment of acute myocardial infarction (MI), the prevention of sudden cardiac death (SCD), the most common mode of death in patients with MI, remains challenging. Furthermore, previous Korean MI registries did not address the issue of post-MI SCD. Additional risk stratifiers of post-MI SCD are still required to compensate for the limitation of using left ventricular ejection fraction to predict lethal arrhythmic events. SUBJECTS AND METHODS: We designed the first Korean prospective nationwide multicenter registry primarily focused on SCD; the Korean noninvasive Risk Evaluation study for sudden cardiac DEath From INfarction or heart failurE (K-REDEFINE). The registry consists of 2 groups of patients presenting with (1) acute MI or (2) acute heart failure (HF) at 25 tertiary referral cardiovascular centers. The primary endpoint of the MI group study of K-REDEFINE registry is the incidence and risk factors of post-MI SCD. In particular, the association between the risk of SCD and non-invasive Holter-based electrocardiogram (ECG) variables will be evaluated, such as T-wave alternans (marker of repolarization heterogeneity) and heart rate turbulence/variability (a marker of autonomic function). Other secondary study outcomes include atrioventricular arrhythmias, HF-related admission, repeated myocardial ischemic events, stroke, and overall deaths. CONCLUSION AND PERSPECTIVE: The K-REDEFINE registry will provide new prospects for the better management of MI patients with high risk of SCD by clarifying the burden and predictors of SCD and the clinical utility of various non-invasive ambulatory ECG-based variables in risk stratification for SCD in this patient population.

Design of Korean Noninvasive Risk Evaluation Study for Sudden Cardiac Death from Infarction or Heart Failure: Heart failure study of K-REDEFINE registry

BACKGROUND AND OBJECTIVES: Sudden cardiac death (SCD) is one of the most common causes of death in patients with heart failure (HF). However, there are no available data on SCD in previous Korean HF registries. Additionally, although widely used, the utility of left ventricular (LV) ejection fraction (EF) in risk stratification for SCD is limited. SUBJECTS AND METHODS: The Korean non-invasive Risk Evaluation study for sudden cardiac DEath From INfarction or heart failurE (KREDEFINE) is the first Korean prospective, nationwide multicenter registry, primarily focused on SCD. The registry consists of 2 groups of patients presenting with (1) acute HF or (2) acute myocardial infarction (MI) at 25 tertiary referral cardiovascular centers. Using the HF-group data of the K-REDEFINE registry, the incidence and risk factors of SCD in patients with HF will be assessed. In particular, the efficacy of Holter-based ECG variables, such as T-wave alternans (marker of repolarization heterogeneity) and heart rate turbulence/ variability (maker of autonomic function), in risk stratification for SCD will be evaluated. Other cardiovascular outcomes will also be analyzed, including atrioventricular arrhythmias, HF-related admission, stroke, and overall deaths. CONCLUSION AND PERSPECTIVE: The K-REDEFINE registry will pave the way for better management of patients with HF at high risk of SCD by elucidating the burden and risk factors of SCD and the clinical utility of various non-invasive ambulatory ECG-based parameters in risk stratification for SCD in this patient population.

Effects of Angiotensin-II Receptor Blocker on Inhibition of Thrombogenicity in a Canine Atrial Fibrillation Model

BACKGROUND AND OBJECTIVES: Angiotensin-II receptor blockers (ARBs) are known to reduce the development of atrial fibrillation (AF) through reverse-remodeling. However, the effect of ARBs on thrombogenicity in AF remains unknown. MATERIALS AND METHODS: Twelve dogs were assigned to control (n=4), ARB (candesartan cilexitil 10 mg/kg/day p.o., 12 weeks; n=4), or sham (n=4) groups. Sustained AF was induced by rapid atrial pacing. Both arterial and venous serum levels of tissue inhibitor of matrix metalloproteinase-1, von Willebrand factor, P-selectin, and vascular cell adhesion molecule-1 (VCAM-1) were measured at baseline and during AF (0, 4, and 12 weeks) with enzyme-linked immunosorbent assay. Biopsies from both atria including the appendages were performed to semi-quantitatively assess endocardial and myocardial fibrosis after 12 weeks. RESULTS: The serum levels of bio-markers were not significantly different at baseline or during AF between the control and the candesartan groups. The levels were not significantly different over time, but there was a trend toward a decrease in arterial VCAM-1 from 4 to 12 weeks in the candesartan group compared to the control group. The grades of endocardial fibrosis after 12 weeks but not those of myocardial fibrosis were slightly reduced in the candesartan group compared to the control group. CONCLUSION: This study did not show that the ARB candesartan significantly reverses thrombogenicity or fibrosis during AF. Future studies using a larger number of subjects are warranted to determine the therapeutic effect of renin-angiotensin-aldosterone system blockade on prothrombogenic processes in AF.

Swallowing-Induced Atrial Tachyarrhythmias Successfully Ablated at the Left Posterior Interatrial Septum in Patient with Wolff-Parkinson-White Syndrome

We reported a case of a 55-year-old patient who presented with palpitation after swallowing. Initial surface electrocardiogram revealed ventricular preexcitation utilizing a left lateral bypass tract. The orthodromic atrioventricular reentrant tachycardia (AVRT) was induced during electrophysiologic studies. After successful ablation of the AVRT utilizing a left lateral free wall bypass tract, 2 different atrial tachycardias (ATs) were induced under isoproterenol infusion. When the patient swallowed saliva or drank water, 2 consecutive beats of atrial premature complexes (APCs) preceded another non-sustained AT repeatedly, which was coincident with the patient's symptom. The preceding APC couplet had the same activation sequence with one induced AT, and the subsequent non-sustained AT had the same activation sequence with the other induced AT, respectively. We first targeted the preceding 2 consecutive APCs at the left posterior interatrial septum. The following non-sustained AT was also eliminated following ablation of the APCs. After ablation, the patient remained free from the swallowing-induced atrial tachyarrhythmias during the one year follow-up.

Prognosis after Implantation of Cardioverter-Defibrillators in Korean Patients with Brugada Syndrome

PURPOSE: Our study aims to analyze prognosis after implantable cardioverter-defibrillator (ICD) implantation in Korean patients with Brugada syndrome (BrS). MATERIALS AND METHODS: This was a retrospective study of BrS patients implanted with an ICD at one of four centers in Korea between January 1998 and April 2012. Sixty-nine patients (68 males, 1 female) were implanted with an ICD based on aborted cardiac arrest (n=38, 55%), history of syncope (n=17, 25%), or induced ven tricular tachyarrhythmia on electrophysiologic study in asymptomatic patients (n=14, 20%). A family history of sudden cardiac death and a spontaneous type 1 electrocardiography (ECG) were noted in 13 patients (19%) and 44 patients (64%), respectively. RESULTS: During a mean follow-up of 59+/-46 months, 4.6+/-5.5 appropri ate shocks were delivered in 19 patients (28%). Fourteen patients (20%) experienced 5.2+/-8.0 inappropriate shocks caused by supraventricular arrhythmia, lead failure, or abnormal sensing. Six patients were admitted for cardiac causes during follow-up, but no cardiac deaths occurred. An episode of aborted cardiac arrest was a significant predictor of appropriate shock, and the composite of cardiac events in the Cox pro portional hazard model [hazard ratio (95% confidence interval) was 11.34 (1.31-97.94) and 4.78 (1.41-16.22), respectively]. However, a spontaneous type 1 ECG was not a predictor of cardiac events. CONCLUSION: Appropriate shock (28%) and inappropriate shock (20%) were noted during a mean follow-up of 59+/-46 months in Korean BrS patients implanted with an ICD. An episode of aborted cardiac ar rest was the most powerful predictor of cardiac events.

Inadvertently Developed Ventricular Fibrillation during Electrophysiologic Study and Catheter Ablation: Incidence, Cause, and Prognosis

BACKGROUND AND OBJECTIVES: Ventricular fibrillation (VF) can inadvertently occur during electrophysiologic study (EPS) or catheter ablation. We investigated the incidence, cause, and progress of inadvertently developed VF during EPS and catheter ablation. SUBJECTS AND METHODS: We reviewed patients who had developed inadvertent VF during EPS or catheter ablation. Patients who developed VF during programmed ventricular stimulation to induce ventricular tachycardia or VF were excluded. RESULTS: Inadvertent VF developed in 11 patients (46.7+/-9.3 years old) among 2624 patients (0.42%); during catheter ablation for atrial fibrillation (AF) in nine patients, frequent ventricular premature beats (VPBs) in one, and Wolff-Parkinson-White (WPW) syndrome were observed in one. VF was induced after internal cardioversion in six AF patients due to incorrect R-wave synchronization of a direct current shock. Two AF patients showed spontaneous VF induction during isoproterenol infusion while looking for AF triggering foci. The remaining AF patient developed VF after rapid atrial pacing to induce AF, but the catheter was accidentally moved to the right ventricular (RV) apex. A patient with VPB ablation spontaneously developed VF during isoproterenol infusion. The focus of VPB was in the RV outflow tract and successfully ablated. A patient with WPW syndrome developed VF after rapid RV pacing with a cycle length of 240 ms. Single high energy (biphasic 150-200 J) external defibrillation was successful in all patients, except in two, who spontaneously terminated VF. The procedure was uneventfully completed in all patients. At a mean follow-up period of 17.4+/-15.5 months, no patient presented with ventricular arrhythmia. CONCLUSION: Although rare, inadvertent VF can develop during EPS or catheter ablation. Special caution is required to avoid incidental VF during internal cardioversion, especially under isoproterenol infusion.

Unusual Polymorphic Ventricular Tachycardia Originating from the Pulmonary Artery

We report a case about a 27-year-old healthy young male who developed syncope during exercise, which was subsequently identified to be attributable to non-sustained polymorphic ventricular tachycardia (VT). Occurrence of polymorphic VT was neither related to a prolonged QT interval nor a fixed short coupling interval. Standard examinations including echocardiography, coronary angiography, isoproterenol infusion study, and cardiac MRI showed no structural heart disease. On the electrophysiology study, activation mapping revealed that a discrete potential preceded the premature ventricular complex (PVC) triggered polymorphic VT, which was recorded just above the pulmonary valve. After radiofrequency ablation at this area, PVC and polymorphic VT disappeared and did not recur after a 2 month follow up.

Unusual Polymorphic Ventricular Tachycardia Originating from the Pulmonary Artery

We report a case about a 27-year-old healthy young male who developed syncope during exercise, which was subsequently identified to be attributable to non-sustained polymorphic ventricular tachycardia (VT). Occurrence of polymorphic VT was neither related to a prolonged QT interval nor a fixed short coupling interval. Standard examinations including echocardiography, coronary angiography, isoproterenol infusion study, and cardiac MRI showed no structural heart disease. On the electrophysiology study, activation mapping revealed that a discrete potential preceded the premature ventricular complex (PVC) triggered polymorphic VT, which was recorded just above the pulmonary valve. After radiofrequency ablation at this area, PVC and polymorphic VT disappeared and did not recur after a 2 month follow up.

Electrophysiological Characteristics Related to Outcome after Catheter Ablation of Idiopathic Ventricular Arrhythmia Originating from the Papillary Muscle in the Left Ventricle

BACKGROUND AND OBJECTIVES: The electrophysiological properties associated with favorable outcome of radiofrequency catheter ablation (RFCA) for idiopathic ventricular arrhythmia (VA) originating from the papillary muscle (PM) remain unclear. The purpose of this study was to investigate the relationships of electrophysiological characteristics and predictors with the outcome of RFCA in patients with VAs originating from PM in the left ventricle (LV). SUBJECTS AND METHODS: Twelve (4.2%) of 284 consecutive patients with idiopathic VAs originating from LV PM were assessed. The electrophysiological data were compared between the patients in the successful group and patients in the recurrence group after RFCA. RESULTS: In 12 patients with PM VAs, non-sustained ventricular tachycardias (VTs, n=6), sustained VTs (n=4) and premature ventricular complexes (n=2) were identified as the presenting arrhythmias. Seven of eight patients showing high-amplitude discrete potentials at the ablation site had a successful outcome (85.7%), while the remaining four patients who showed low-amplitude fractionated potentials at the ablation site experienced VA recurrence. The mean duration from onset to peak downstroke (Deltat) on the unipolar electrogram was significantly longer in the successful group than in the recurrence group (58+/-8 ms vs. 37+/-9 ms, p=0.04). A slow downstroke >50 ms of the initial Q wave on the unipolar electrogram at ablation sites was also significantly associated with successful outcome (85.7% vs. 25.0%, p=0.03). CONCLUSION: In PM VAs, the high-amplitude discrete potentials before QRS and slow downstroke of the initial Q wave on the unipolar electrogram at ablation sites were related to favorable outcome after RFCA.

Characteristics and Outcomes of Atrial Tachycardia Originating from the Sinus Venosus during Catheter Ablation of Atrial Fibrillation

BACKGROUND AND OBJECTIVES: The sinus venosus (SV) is not a well known source of atrial tachycardia (AT), but it can harbor AT during catheter ablation of atrial fibrillation (AF). SUBJECTS AND METHODS: A total of 1223 patients who underwent catheter ablation for AF were reviewed. Electrophysiological and electrocardiographic characteristics and outcomes after catheter ablation of AT originating from the SV were investigated. RESULTS: Ten patients (0.82%) demonstrated AT from the SV (7 males, 53.9+/-16.0 years, 6 persistent) during ablation of AF. The mean cycle length was 281+/-73 ms. After pulmonary vein isolation and left atrial ablation, AF converted to AT from the SV during right atrial ablation in 2 patients, by rapid atrial pacing after AF termination in 7 patients, and during isoproterenol infusion in 1 patient. Positive P-waves in inferior leads were shown in most patients (90%). The activation sequence of AT was from proximal to distal in the superior vena cava and high to low in the right atrium, which was similar to that of AT from crista terminalis. Fragmented double potentials were recorded during sinus, and a second discrete potential preceded the onset of P wave by 80+/-37 ms during AT. Using 4.4+/-2.7 radiofrequency focal applications, ATs were terminated and became no longer inducible in all. After ablation procedure, two patients showed transient right phrenic nerve palsy. After 19.9+/-14.8 months, all but 1 patient were free of atrial tachyarrhythmia without complications. CONCLUSION: The AT which develops during AF ablation is rarely originated from SV, and its electrophysiologic characteristics may be helpful in guiding effective focal ablation.

Effect of Human Bcl-2 Gene Expression on the Peripheral Atherosclerotic Lesions of Apolipoprotein E-Deficient Mouse

BACKGROUND AND OBJECTIVES: Bcl-2 protein is related to the inhibition of apoptosis via the mitochondrial pathway and Bcl-2's anti-oxidant effect. During the development of atherosclerosis, apoptosis is known to play an important role in the pathophysiologic behavior of atherosclerotic vascular disease in the medium-sized arteries. Apoptosis may be a compensatory reaction to regulate the cellular density of various tissues during the cellular proliferation process such as happens with tissue injury and during the development of atherosclerosis. The consequences of apoptosis in atherosclerosis may be related to the formation of an acellular lipid core, plaque instability and the loss of vascular wall integrity and remodeling. We sought to determine the effect of Bcl-2 gene expression on the development of primary atherosclerosis in apolipoprotein E deficient mouse, which is one of the typical animal models that are used for the development of peripheral atherosclerosis. MATERIALS AND METHODS: Bcl-2 transgenic mice were cross hybridized with apolipoprotein E deficient mice. Systemic analysis of the distribution and severity of their atherosclerotic lesions was done by dissecting microscopy, and the histological characteristics of the lesions were evaluated in normal chow-fed, 9-month-old apolipoprotein-E deficient/Bcl-2 transgenic mice (n=6) and apolipoprotein-E deficient mice (n=6). RESULTS: The distribution and severity of atherosclerotic lesions at the peripheral arteries were less in the apolipoprotein-E deficient/Bcl-2 transgenic mice. Acellular lipid core formation, destruction of the smooth muscle cell layers in the media and infiltration of inflammatory cells in the adventitia were much less in the apolipoprotein-E deficient/Bcl-2 transgenic mice. The lipid profile was similar in both groups. CONCLUSION: The effect of Bcl-2 gene expression on the peripheral atherosclerosis was related with the inhibition or the delay of atherosclerotic lesion progression, such as the reduction of amount of the acellular lipid core, maintenance of vascular smooth muscle cell integrity and the reduction of adventitial inflammation, and this was achieved regardless of serum cholesterol level.

Initiation and Maintenance Mechanism of Atrial Fibrillation Assessed by 3-Dimensional Non-Contact Mapping System

BACKGROUND AND OBJECTIVES: We undertook this study to assess the initiation and maintenance mechanisms of atrial fibrillation (AF) and their relationships with the anatomical structures of the left atrium (LA) and pulmonary veins (PVs). SUBJECTS AND METHODS: Thirty-seven patients (33 men, mean age 50, range 25-68 years) with paroxysmal AF (n=29) and persistent AF (n=8) who underwent mapping of the LA and PV using 3D non-contact endocardial mapping system (EnSite 3000) were enrolled. The multielectrode array and ablation catheter were positioned in the LA via the double transseptal approach. Atrial premature beats (APBs) which triggered initiation of AF that lasted longer than 1 min were mapped and the activation sequence was analyzed on isopotential color maps. Wave front dynamics and the relationship with the underlying structures were assessed. RESULTS: More than half, 56.4%, of APBs from PV were related to the initiation of AF, but not related to the maintenance of AF. A quarter, 25.6%, of APBs from PV not only initiated AF, but also maintained AF without continuous triggering. Mixed type and indeterminate type of AF was 5.0% and 12.8%, respectively. During AF, the mean number of wavelets was 1.45 (maximum 3 in 76.5%). Anatomical structures showing slow conduction and wavebreaks were mostly located at the septopulmonary bundle (86.5%) and the posterior roof of the LA between the left superior PV and right superior PV (54.1%). CONCLUSION: Focal repetitive activity from PV played an important role in both the initiation and maintenance of AF. Specific anatomical structures such as septopulmonary bundle or posterior roof of the LA were related to the heterogeneous conduction delay and spontaneous wavebreak, which was also important in the maintenance of AF.

Acute Effect of Intravenous Propafenone for Atrial Fibrillation Refractory to Transthoracic Electrical Cardioversion

BACKGROUND AND OBJECTIVES: Various intravenous (IV) antiarrhythmic drugs in patients with atrial fibrillation (AF) refractory to electrical cardiooversion have been attempted. We assessed the efficacy of IV propafenone in patients with AF who failed to achieve normal sinus rhythm using standard external direct current (DC) cardioversion. SUBJECTS AND METHODS: Of the 77 AF patients who underwent a DC cardioversion, 18, who were refractory for up to a maximal 360 joules of external DC cardioversion, were included in this study. Propafenone was infused for 10 minutes at doses of 2 mg/kg (n=3), 2.5 mg/kg (n=8), and 3 mg/kg (n=7) followed by repeated DC cardioversion. RESULTS: The mean age of the patients receiving propafenone was 55+/-14 years and 21% were women. The mean ejection fraction and the average diameter of the left atrium were 56+/-5% and 42+/-7 mm, respectively. The AF cycle length increased following propafenone infusion form 160+/-23 ms to 278+/-62 ms (p<0.05). The AF converted to a normal sinus rhythm following propafenone infusion in three patients. Thirteen patients were successfully cardioverted following IV propafenone infusion, with a mean accumulated energy of 410+/-216 joules (689+/-373 joules prior to propafenone infusion, p<0.05). Cardioversion failed in 2 patients;therefore, the success rate of the cardioversion in patients who received IV propafenone was 88.9% (16/18). No significant adverse effects were observed. CONCLUSION: IV propafenone can be safely used to enhance the efficacy of cardioversion in patients with AF refractory to transthoracic DC cardioversion.

Vessel Size and Long-Term Clinical and Angiographic Outcome after Primary Stenting in Acute Myocardial Infarction

BACKGROUND AND OBJECTIVES: The role of coronary stenting in the treatment of patients with small vessels ( or =3.0 mm. The primary end points were the major adverse cardiac events including death, recurrent myocardial infarction, or target vessel revascularization at follow-up. The incidence of angiographic restenosis (> or = 50% of diameter stenosis) was assessed as a secondary end point. Event-free survival in the small vessel group (less than 3mm of reference vessel diameter) was 62.5% at 23.7+/-13.0 months and 76% in the large vessel group (p<0.001) at 23.5+/-12.0 months. The follow-up angiographic restenosis rate was significantly higher in the small vessel group (61% vs. 32% in the small and large vessel groups, respectively, p=026). CONCLUSION: Acute myocardial infarction patients with small vessels present a higher risk for an adverse outcome following primary stenting.

The Efficacy and Safety of Outpatient Coronary Angiography

BACKGROUND: Coronary angiography have become important and integral components in the investigation of patients with cardiovascular disease. Technical improvement combined with an increased need of coronary angiography, and efforts to decrease the length of inpatient hospital stay have prompted the development of outpatient coronary angiography. In this study, we compared the procedure-related complications and costs of inpatient and outpatient coronary angiography when performed at the same institution. In addition, we attempted the coronary angiography as outpatient setting in patients with unstable angina, old age, and anticoagulation therapy, who have been regarded as contraindication for outpatient procedure. METHODS: Diagnostic coronary angiography was performed in 199 cases as inpatient setting, and 225 cases as outpatient setting at Korea University Guro Hospital From January through July 1996. There was no significant difference in sex, age, risk factor, blood pressure, cholesterol level, and ejection fraction. We did not give the heparin during the procedure and, use the Judkins' method in all patients. After the procedure, pressure dressing was done with compressor device for 15 minutes, then sandbag was applied on the puncture site. In outpatient, they took bed rest for 6 hours in one-day care room. RESULTS: 1) In the inpatient group, there were 6 cases(3.0%) of catheterization-related complication, and there were 7 cases(3.1%) of complication in the outpatient group. There was no major complication in both groups, such as death, myocardial infarction, stroke, and perforation of heart and great vessels. In the inpatient group, 2 cases of arrhythmia, 3 cases of hematoma at puncture site, and 1 case of femoral artery pseudoaneuryrsm occurred. In the outpatient group, 2 cases of arrhythmia, 1 case of hematoma at puncture site, 2 cases of skin rash, 1 case of acute febrile reaction, and 1 case of femoral artery dissecting aneurysm developed. There was no significant difference in the rate of complications between two groups(p=0.947). 2) In the outpatient group, there were 28 cases of unstable angina, 6 cases of old age more than 75 years, and 5 cases of anticoagulant has been taken. No catheterization-related complication occurred in those groups. 3) The costs and duration of hospital stay in the inpatient group were won480,230+/-86,800 and 50.3+/-12.3 hours and those in the outpatient group were won276,870+/-32,050 and 8.3+/-1.2 hours. There was significant difference between two groups in the costs and duration of hospital stay(p<0.01, p<0.01). CONCLUSIONS: Outpatient coronary angiography could be done safely with low complication rate, and could reduce the costs and hospital stay. For high risk group such as unstable angina, old age, and anticoagulation therapy, there was no complication in this study, but more experiences and available data should be accumulated to be accepted as a general guideline.

Diagnostic Value of QT and JT Dispersion in Exercise ECG

BACKGROUND: QT dispersion(QTD : QTmax-QTmin) or JT dispersion(JTD:JTmax-JT-min)in 12 leads ECG has been known to reflect regional variations in ventricular repolarization and has been reported to bel one of the marker of regional myocardial ischemia. To evaluate the significance of QTD or JTD of exercise ECG in diagnosis of coronary artery disease, we studied 106 patients(mean age, 56.9 years old, male 63) who were referred for the evaluation of chest pain on exertion. METHOD: Treadmill exercise stress test with modified Bruce protocol and coronary angiography were performed in 106 patients with chest pain on exertion. ST-segment depression by >1.0 mm 0.08 second after J-point during or after exercise in exercise test and >50% stanosis of epicardial artery in coronary angiogram were defined as positive. Of 106 patients, 41 had positive exercise ECG and positive coronary angiogram(true positive, TP), 20 had positive exercise ECG and negative coronary angiogram(false positive, FT), 20 had negative exercise ECG and positive coronary angiogram(faalse negative, FN), and 23 had negative exercise ECG and negative coronary angiogram(true negative, Tn). QT and JT interval in 12 leads were measured at baseline and peakexercise and were corrected for heart rate using Bazett's formula. QTD and JTD were measured by calculation the difference between the maximum QT and mininum QT and that between maximum JT and minumum JT. RESULTS: QTD at baseline for TP(72.8ms)was prolonged compared to Tn(52.2ms,P<0.01), but was not different from that for FT(70.2 ms). At peak exercise, QTD for TP(81.3 msec) was significantly prolonged(p<0.01), while QTD for FP(71.2 msec) was not different from that for TN(56.8 msec). JTD at baseline(78.4 msec) and at peak exercise(88.2 msec) for TP were significantly prolonged compared to those for TN(55.2msec and 55.1msec p<0.01,p<0.01, respectively), but those for FP were not porlonged(77.0msec and 79.0msec, respectively). QTD and JTD at peak exercise were more markedly prolonged in patients with sever stenosis of coronary artery(p=0.053 and p<0.05, repectively) and multivessels diseases(p<0.01, 0<0.05) than those with less severe disease and single vessel disease. Patients with left anterior descending artery lesion had greater QTD and JTD at peak exercise than those with other vessels lesion(p<0.01). In addition to standard criteria with ST segment displacement in exercise EGC, inclusion of exercise induced QTD of more than 60msec increased the sensitivity of exercise ECG from 66.7% to 83.3%, and JTD of more than 70msec increased the specificity from 52% to 76.0%. CONCLUSION: Measurement of QT dispersion and JT dispersion of exercise ECG may be useful method to identify the severity of coronary artery disease and to improve diagnostic accuracy of exercise ECG in coronary artery disease.