The Association Between the Pattern of Premature Ventricular Contractions and Heart Diseases: Assessment of Routine Electrocardiography in Health Examinations

Journal of J Occup Health 2002; 44: 343Ð347 Occupational Health

The Association between the Pattern of Premature Ventricular Contractions and Heart Diseases: Assessment of Routine Electrocardiography in Health Examinations

Kazuhito HATANAKA1, Akira FUJINAMI2, Yoshihiro NISHIMOTO2, Nobuhiko ITO3 and Masahiko KOBAYASHI1

1Department of Forensic Medicine, Graduate School of Medicine, University of Tokyo, 2Central Health Institute of East Japan Railway Company and 3Department of Cardiology, JR Tokyo General Hospital, Japan

Abstract: The Association between the Pattern of findings applied to the observations in asymptomatic Premature Ventricular Contractions and Heart subjects. Conclusion—It is suggested that the Diseases: Assessment of Routine population without heart disease primarily has the PVCs Electrocardiography in Health Examinations: of the LBBB pattern without axis deviation and the Kazuhito HATANAKA, et al. Department of Forensic analysis of the PVC patterns (bundle branch block Medicine, Graduate School of Medicine, University pattern) and of electrical axis deviation in routine ECG of Tokyo—Objective—Premature ventricular at a routine health examination is useful for diagnosing contractions (PVCs) were observed among patients heart disease. with heart diseases. It has been suggested that the (J Occup Health 2002; 44: 343Ð347) sporadic left bundle branch block (LBBB) pattern of PVCs observed in healthy subjects has no relevance Key words: Premature ventricular contractions, Heart to heart diseases and the presence of this type of PVC disease, Electrocardiography, Bundle branch block, was not associated with a poor prognosis. The aim of Electrical axis deviation this study is to present and evaluate the relationship between PVC patterns on routine electrocardiography Arrhythmia is one of the markers of heart disease. (ECG) and heart diseases. Methods: The subjects Premature ventricular contractions (PVCs) are the most examined were 201 employees from one company common type of arrhythmia and PVCs are suggested to be (male 192, female 9) with PVCs (Lown grading associated with heart diseases, such as ischemic heart classification 0 or 1). The patterns of PVCs were disease, cardiomyopathy, obstructive pulmonary disease classified into the following four categories regarding 1Ð3) the bundle branch block pattern and electrical axis and valvular disease . In ischemic heart disease, frequent, deviation: 1) the LBBB pattern without axis deviation multiform or early-coupling (R-on-T phenomenon) PVCs (135 subjects), 2) the LBBB pattern with left axis are regarded as warning arrhythmias4, 5). PVCs also occur deviation (29 subjects), 3) the right bundle branch block in relation to various stimuli such as electrolyte (RBBB) pattern without axis deviation (22 subjects) and imbalance, tension states and central and peripheral 4) the RBBB pattern with left axis deviation (15 autonomic stimulation6). Therefore, when PVCs are subjects). Results—The presence of subjective detected by electrocardiography (ECG), a close symptoms was not significant in each category. examination is often required to investigate the presence Prevalence of heart disease was 1) 14 (10.4%), 2) 10 of underlying disease. PVCs are also provoked by (34.5%), 3) 9 (40.9%) and 4) 7 (46.7%). The subjects smoking as well as caffeine or alcohol intake3, 6, 7), so that with the LBBB pattern without axis deviation had a lower they are frequently observed in a healthy population. incidence of having heart disease than subjects with other PVC patterns (p<0.05). In addition, similar Other studies have shown that PVCs in healthy subjects are sporadic and show no connection with heart disease8Ð13). Received Feb 8, 2002; Accepted June 13, 2002 In the PVCs of subjects without heart disease, the left Correspondence to: K. Hatanaka, Department of Forensic bundle branch block (LBBB) pattern varied from 60 to Medicine, Graduate School of Medicine, University of Tokyo, 7Ð 96% and the right bundle branch block (RBBB) pattern 3Ð1 Bunkyo-Ku, Hongo, Tokyo 113-0033, Japan varied from 4 to 33%10Ð12). In the PVCs of subjects with 344 J Occup Health, Vol. 44, 2002 heart disease, the LBBB pattern varied from 18 to 22% Table 1. Characterization of premature ventricular and the RBBB pattern varied from 73 to 83%12). In contraction in 201 subjects subjects without ischemic heart disease, the LBBB pattern Pattern of PVCs No. % of group was 74%, the RBBB pattern was 17% and both pattern were 9%13). In subjects with ischemic heart disease, the LBBB without AD 135 67.2 LBBB pattern was 35%, the RBBB pattern was 46% and LBBB with LAD 29 14.4 both were 19%13). In general, most PVC patterns in RBBB without AD 22 10.9 healthy subjects show an LBBB pattern. In addition to RBBB with LAD 15 7.5 the PVC pattern, it is also useful to make other observations regarding the presence or absence of heart Total 201 100 disease on routine ECG at a health examination. We Abbreviations: PVCs=premature ventricular contractions; therefore studied the degree of electrical axis deviation LBBB=left bundle branch block; RBBB=right bundle as a useful indicator. branch block; AD=axix deviation; LAD=left axis deviation. In the present study we analyzed sporadic PVC patterns (bundle branch block pattern) and electrical axis deviation in 201 subjects in routine ECGs. We also examined the association between PVC patterns, electrical axis investigated in each category and the symptoms deviation and the presence of heart disease. associated with PVCs were detected, such as palpitations, discomfort in the chest or feeling that the heart stopped Subjects and Methods during the long pause after PVCs6). The subjects of this study were 201 employees from Statistical significance was established by chi-square one company who had one or more PVCs on a routine analysis with Bonferroni correction for multiple 12-lead ECG obtained during a health examination. There comparisons. Statistical differences were judged were 192 males and 9 females, with ages ranging from significant at p<0.05. 19 to 56 yr (mean of 44.4 yr). All subjects underwent a clinical examination for heart diseases in medical facilities Results and their medical history was reviewed. Subjects with Individual classifications are shown in Table 1. The atrial fibrillation (valvular heart disease, lone atrial heart disease diagnoses were as follows: 20 had fibrillation, ischemic heart disease, cardiomyopathy), hypertensive cardiovascular disease, 11 had ischemic conduction disturbance (atrioventricular block, left bundle heart disease, 5 had cardiomyopathy and 4 had valvular branch block, right bundle branch block, Wolff- heart disease. In excluded subjects, one at Lown’s grade Parkinson-White syndrome), who were taking 3 had neither symptoms nor heart disease and another at antiarrhythmics drugs or who showed poorly recorded Lown’s grade 4A had symptoms and ischemic heart ECG tracing were excluded from the study population. disease. Subjects corresponding to Lown’s grades14) 2Ð5 were also 135 subjects had the LBBB pattern without axis excluded. The QRS complexes were diagnosed as PVCs deviation, 29 had the LBBB pattern with left axis not by automatic data processing, but by physicians deviation, 22 had the RBBB pattern without axis deviation according to the following criteria: (1) premature, (2) not and 15 had the RBBB pattern with left axis deviation. preceded by a premature P wave, (3) with a duration of Of the 201 subjects, 25 had symptoms associated with 0.12 s or greater and (4) with a different morphology PVCs and 176 were asymptomatic. Of the 25 subjects from the dominant rhythm13). The RBBB pattern was with symptoms, 11 had heart disease and 29 did not. Of diagnosed when there was a QRS duration of 0.12 s or the 176 asymptomatic subjects, 29 had heart disease and greater with a QR, RSR’ or RR’ pattern in the V1 lead15). 147 did not (Table 2). The asymptomatic subjects had a The LBBB pattern was diagnosed when there was a QRS lower incidence of heart disease than the symptomatic duration of 0.12 s or greater and a predominantly negative subjects (p<0.05). QRS complex with a terminal S wave in the V1 lead16). Of the 135 subjects with the LBBB pattern without The mean electrical axis deviation was measured in the axis deviation, 16 had symptoms related to PVCs and QRS complex, and the QRS frontal-plane vector, between 119 had no symptoms. Of the 29 subjects with the LBBB Ð30° and Ð90°, was defined as left axis deviation17, 18). pattern with left axis deviation, 4 had symptoms and 25 Subjects were placed into the following four categories, had no symptoms. Of the 22 subjects with the RBBB based on their PVC patterns and electrical axis deviation: pattern without axis deviation, 3 were symptomatic and (1) LBBB pattern without axis deviation, (2) LBBB 19 were asymptomatic. Of the 15 subjects with the RBBB pattern with left axis deviation, (3) RBBB pattern without pattern with left axis deviation, 2 were symptomatic and axis deviation, (4) RBBB pattern with left axis deviation. 13 were asymptomatic. There was no significant The presence or absence of heart disease was also difference between the categories regarding the presence Kazuhito HATANAKA, et al.: Association between PVC Patterns and Heart Disease 345

Table 2. Association between symptoms and heart diseases

Subjects Symptomatic (%) Asymptomatic (%) Total

Heart diseases 11 (44.0) 29 (16.5) 40 No heart diseases 14 (56.0) 147 (83.5) 161 Total 25 176 201 χ2=13.1 (p<0.05)

Table 3. Association between PVC patterns and symptoms

Pattern of PVCs Subjects LBBB without LBBB with RBBB without RBBB with Total AD (%) LAD (%) AD (%) LAD (%)

Symptomatic 16 (11.9) 4 (13.8) 3 (13.6) 2 (13.3) 25 Asymptomatic 119 (88.1) 25 (86.2) 19 (86.4) 13 (86.7) 176 Total 135 29 22 15 201 χ2=0.168 (N.S.)

Abbreviations: PVCs=premature ventricular contractions; LBBB=left bundle branch block; RBBB=right bundle branch block; AD=axis deviation; LAD=left axis deviation.

Table 4. Association between PVC patterns and heart diseases

Pattern of PVCs Subjects LBBB without LBBB with RBBB without RBBB with Total AD (%) LAD (%) AD (%) LAD (%)

Heart diseases 14 (10.4) 10 (34.5) 9 (40.9) 7 (46.7) 40 No heart diseases 121 (89.6) 19 (65.5) 13 (59.1) 8 (53.3) 161 Total 135 29 22 15 201 χ2=23.4 (p<0.05)

Abbreviations: PVCs=premature ventricular contractions; LBBB=left bundle branch block; RBBB=right bundle branch block; AD=axis deviation; LAD=left axis deviation.

or absence of symptoms (Table 3). not. Of the 25 subjects with the LBBB pattern with left The relationships between the PVC patterns and the axis deviation, 7 had heart disease and 18 did not. Of the presence of heart disease are shown in Table 4. Of the 19 subjects with the RBBB pattern without axis deviation, 135 subjects with the LBBB pattern without axis 9 had heart disease and 10 did not. Of the 13 subjects deviation, 14 had heart disease and 121 did not. Of the with the RBBB pattern with left axis deviation, 5 had 29 subjects with the LBBB pattern with left axis deviation, heart disease and 8 did not. Asymptomatic subjects with 10 had heart disease and 19 did not. Of the 22 subjects the LBBB pattern without axis deviation had a lower with the RBBB pattern without axis deviation, 9 had heart incidence of heart disease than subjects with other PVC disease and 13 did not. Of the 15 subjects with the RBBB patterns (p<0.05). pattern with left axis deviation, 7 had heart disease and 8 did not. Subjects with the LBBB pattern without axis Discussion deviation had a lower incidence of having heart disease We investigated the association between PVC patterns than subjects with other PVC patterns (p<0.05). with electrical axis deviation and the presence of heart The data from 176 asymptomatic subjects are shown disease on routine ECG at a health examination in one in Table 5. Of the 119 subjects with the LBBB pattern company. The sporadic LBBB pattern of PVCs without without axis deviation, 8 had heart disease and 111 did axis deviation showed a significantly low incidence of 346 J Occup Health, Vol. 44, 2002

Table 5. Association between PVC patterns and heart diseases (for asymptomatic subjects)

Pattern of PVCs Subjects LBBB without LBBB with RBBB without RBBB with Total AD (%) LAD (%) AD (%) LAD (%)

Heart diseases 8 (6.7) 7 (28.0) 9 (47.4) 5 (38.5) 29 No heart diseases 111 (93.3) 18 (72.0) 10 (52.6) 8 (61.5) 147 Total 119 25 19 13 176 χ2=27.8 (p<0.05)

Abbreviations: PVCs=premature ventricular contractions; LBBB=left bundle branch block; RBBB=right bundle branch block; AD=axis deviation; LAD=left axis deviation.

heart disease. is required. The focus of PVC can be identified by QRS The reason why PVCs predominantly originate in the morphology; that is, the QRS complexes with the LBBB right ventricle (LBBB pattern) in the absence of heart pattern characterize right ventricular ectopic contractions disease is not clear. According to a survey of and the RBBB pattern characterize left ventricular ectopic asymptomatic, healthy subjects, the ratio of the LBBB contractions13, 19, 20). In addition, PVCs originating within pattern to the RBBB pattern is 3 to 111). It is possible that the anterior division of the left bundle branch or the these LBBB pattern PVCs reflect abnormalities in the anterior left ventricular wall present the RBBB pattern right ventricle and these abnormalities cannot be detected with left posterior hemiblock, and those originating within clinically or even with invasive examination the posterior division of the left bundle branch or the (catheterization)22) or these PVCs may be prodromus of posterior left ventricular wall present the RBBB pattern the development of heart disease23), so that all LBBB with left anterior hemiblock17, 19, 20). Thus, the focus of patterns do not always relate to the absence of heart the ventricular extrasystoles contributes to the QRS disease. morphology and since the majority of the PVCs in normal It is well known that Brugada syndrome causes cardiac subjects have the LBBB pattern, the focus must be the arrest from ventricular fibrillation24). In patients with right ventricle7, 11, 12). It is also suggested that the origin Brugada syndrome, the right precordial lead (V1-V3) is near the interventricular septum21). It is possible that patterns resemble those seen in RBBB with variable ST- the QRS morphology of the PVCs is altered by differences segment elevation and a coved or saddle-type appearance, in the focus, because, anatomically, there is the Purkinje and left axis deviation is occasionally present25). Recently, network of left and right bundle branches in the screening of some families with Brugada syndrome has interventricular septum10). It is reported that the QRS revealed a distinct mutation in the gene associated with morphology of PVCs varies according to the focus in the functional abnormalities of channel behavior24). In view conduction system10). Consequently, there is no definite of this finding, it is possible that some pathophysiological tendency regarding the QRS morphology pattern of PVC, disorder could be disclosed by a new examination such when its origin is located in or near the interventricular as molecular biological techniques, in subjects with PVCs septum. Therefore, it is proposed that in populations without heart disease. without heart disease, if the LBBB pattern has left axis Although in the present study subjects without heart deviation, the RBBB pattern either lacks axis deviation disease primarily had PVCs of the LBBB pattern without or has left axis deviation, the focus is in or near the axis deviation, heart disease was observed in some cases interventricular septum. with the LBBB pattern lacking axis deviation. In addition, We also recognized that subjects with the LBBB pattern it is reported that the occurrence of PVCs in subjects with left axis deviation had a higher incidence of heart without clinical heart disease is associated with the long- disease than those with the LBBB pattern without axis term increase in risk of cardiovascular disease26). deviation. In the RBBB pattern of PVCs there was no Therefore, for subjects with PVCs, a regular medical significant difference between the pattern with no axis follow-up should be encouraged, and a close examination deviation and the pattern with left axis deviation. The may be necessary in some cases with PVC of the LBBB reason for the predominance of the LBBB pattern with pattern without axis deviation. left axis deviation in the presence of heart disease is In summary, the findings of the present study suggest unclear. 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