Prevalence
and Reproducibility
Ventricular
Arrhythmias
of Exercise-Induced
During Maximal
Exercise Testing in Normal Men
JAMES V. FARIS, MD* PAUL L. McHENRY, MD, JOHN W. STEPHEN
FACC
JORDAN, MD N. MORRIS, MD,
Indianapolis.
FACC
Indiana
From the Krannert Institute of Cardiology and the Department of Medicine, Indiana University School of Medicine, Indianapolis, Ind. This study was supported in part by the Herman C. Krannert Fund, Indianapolis, Grants HL-06306. HL05363 and HL-05749 from the National Heart and Lung Institute, National Institutes of Health, Bethesda, Md., the American Heart Association, Dallas, Texas and the Indiana Heart Association, Indianapolis, Ind. * This work was completed during Dr. Faris’s tenure as the John B. Hickam Memorial Fellow of the American Heart Association, Indiana Affiliate, Inc., Indianapolis. Ind. Address for reprints: Paul L. McHenry, MD, Indiana University School of Medicine, 1100 West Michigan St., Indianapolis, Ind. 46202.
The occurrence of ventricular arrhythmias at rest or during ordinary daily activities has been implicated as a risk factor for future coronaryrelated events and sudden death. However, the clinical significance of exercise-induced ventricular arrhythmias remains uncertain. To assess the prevalence and reproducibility of such arrhythmias, two serial maximal treadmill exercise tests were performed in a study population of 543 male Indiana State policemen at an average interval of 2.9 years. Four hundred sixty-two subjects were clinically free of evidence of cardiovascular disease, and 81 had evidence of definite or suspected cardiovascular disease. The prevalence of exercise-induced ventricular arrhythmias during the first test was 30 percent in men aged 25 to 34 years, 32 percent in those aged 35 to 44 years and 38 percent in those aged 45 to 54 years. The prevalence rate in these age groups with repeat testing was 38, 38 and 42 percent, respectively. These differences were not statistically significant. The group with definite or suspected cardiovascular disease had a greater prevalence of exercise-induced ventricular arrhythmias than normal subjects during both tests but the prevalence rate with repeat testing remained constant. The occurrence of exercise-induced ventricular arrhythmias was reproducible in individual subjects during the second test in 55 percent of 25 to 34 year oids, 58 percent of 35 to 44 year oids and 82 percent of 45 to 54 year olds. Thus, individual reproducibility in two consecutive tests was only slightly greater than reproducibility by chance alone. The group with known or suspected cardiovascular disease demonstrated a trend toward greater reproducibility with repeat testing. Exercise-induced ventricular arrhythmias were not reproducible by type or complexity. The marked variability of exercise-induced ventricular arrhythmias during repeat maximal exercise testing in a clinically normal population appears to negate the usefulness of this finding during a single test as a marker of future cardiovascular disease. Nevertheless, subjects whose arrhythmias were reproducible may form a group destined to manifest clinical cardiovascular disease in long-term follow-up studies.
The occurrence of ventricular arrhvthmias at rest or durine ordinarv daily activities has been implicated as a risk factor for fu&e overt heart disease or sudden death.1-6 With the advent of clinical treadmill exercise testing and electrocardiographic recordings during exercise a high incidence rate of exercise-induced ventricular arrhythmias in clinically normal subjects 7,8 has become apparent. The prevalence of exercise-induced ventricular arrhythmias has been reported to be greater in patients with cardiovascular disease than in normal subjects, 8-12 but such arrhythmias have not been documented as a risk factor for future cardiac events in either group. The potential
March 31, 1976
The American Journal of CARDIOLOGY
Volume 37
617
EXERCISE ARRHYTHMIAS
IN NORMAL SUBJECTS-FARIS
ET AL
TABLE I Staging Program for Graded Treadmill Exercise Testing
Staae
Speed (miles/ hour)
Time (min)
I II III IV V VI VII
3
2.0 3.3 3.3 3.3 3.3 3.3 3.3
z 3 3 z
Grade 1%) 3 : 12 15 18 21
clinical implication of exercise-induced ventricular arrhythmias suggested by these reports warrants assessment of their reproducibility to clarify further their significance in a single exercise test.
In 1972 we reported on the prevalence of exerciseinduced ventricular arrhythmias during maximal treadmill exercise testing of 650 male members of the Indiana State Police Force.8 In this study we report on the prevalence of such arrhythmias during a second maximal treadmill exercise test performed an average of 2.9 years later by 543 subjects from the original study group. The reproducibility of exercise-induced ventricular arrhythmias during repeat testing was determined in subjects who had such arrhythmias on their first test. Materials
and Methods
Five hundred forty-three members of the Indiana State Police Force aged 25 to 58 years underwent repeat self-determined maximal treadmill exercise testing an average of 2.9 years (range 1 to 4 years) after the initial test as a part of a continuing cardiovascular evaluation program being conducted at the Indiana University Medical Center. Before each exercise test the subjects had a complete history and physical examination. Posteroanterior and lateral roentgenograms of the chest were obtained as well as routine laboratory studies that included a complete blood count, urinalysis and determination of fasting blood sugar, urea nitrogen and uric acid and serum triglyceride and cholesterol levels. A resting 12 lead electrocardiogram and a continuous 6 minute rhythm strip were recorded before the maximal treadmill exercise test. During the first evaluation subjects manifesting ventricular arrhythmias at rest were excluded so that the true prevalence of exercise-induced ventricular arrhythmias could be defined, Subjects who manifested new ventricular arrhythmias at rest during the second evaluation were not excluded in determining the reproducibility of exercise-induced ventricular arrhythmias during the second test. They were excluded when the prevalence rates of exercise-induced ventricular arrhythmias were determined for the second test so that the data could be compared with those of the first test. Exercise protocol: Our multistage exercise program (Table I), bipolar horizontal lead system and electrode application technique have previously been described.8 All are designed to obtain optimal noise reduction during max-
616
March31,
1976
The American
Journal
of CARDIOLOGY
imal exercise, thus permitting the detection and classification of arrhythmias. An additional bipolar vertical lead system was used in a portion of the second studies to facilitate further the detection and classification of arrhythmias.13 The electrocardiogram was monitored continuously with an oscilloscope, and direct write-outs were recorded at selected intervals and whenever the monitoring physician or technician observed an arrhythmia. The electrocardiographic signal was also recorded continuously on magnetic tape together with an electronically generated time code. All arrhythmias observed during the exercise test were later located on the tape by means of the time code and a complete write-out was obtained. This procedure permitted a thorough analysis of the arrhythmias with respect to frequency, origin and type (extrasystoles per minute, supraventricular versus ventricular, unifocal versus multifoCal). The data were again reviewed for arrhythmias during analog to digital conversion of the electrocardiographic signal in preparation for computer quantitation of the S-T segment response to exercise.l* The QRS configuration was used as the primary determinant of the origin of the recorded arrhythmias, but the recordings were also studied for premature P waves and partial compensatory pauses in an effort to rule out aberrant intraventricular conduction of supraventricular impulses. Two or more consecutive ventricular premature complexes or multifocal ventricular premature complexes were classified as complex exercise-induced ventricular arrhythmias. Ventricular premature complexes were considered multifocal in origin if two distinctly multiform QRS configurations appeared in the same stage of exercise at essentially the same heart rate. The frequency per minute of the ventricular premature complexes was defined as the maximal number of such complexes recorded during any single minute of exercise or during any minute of the 6 minute recovery period. Classification of test subjects: The 543 subjects were classified into three age groups-25 to 34, 35 to 44 and 45 to 54 years-at the time of their first treadmill test. For purposes of comparison in this study they were continued in their initial age group. The clinical and laboratory data for each subject were reviewed for evidence of cardiovascular disease. At the time of the first evaluation subjects were classified as having definite cardiovascular disease if they had (1) classic exertional angina, (2) a previous documented myocardial infarction, (3) a previous episode of chest pain consistent with myocardial ischemia accompanied by serial ST-T wave changes, (4) evidence of valvular heart disease, (5) persistent resting systolic blood pressure greater than 160 mm Hg or diastolic pressure greater than 96 mm Hg, or (6) symptomatic peripheral vascular or cerebrovascular disease. A diagnosis of “suspected” cardiovascular disease was made if they had (1) experienced one or more episodes of chest pain consistent with myocardial ischemia but without associated electrocardiographic or serum enzyme changes, (2) a positive computer-quantitated S-T segment index in response to maximal exercise,14 or (3) any abnormality of the resting electrocardiogram without other clinical evidence of heart disease (Table II). The subjects were reclassified after the second evaluation if they manifested any of these criteria as a serial change. A statistical analysis was then made of the observed prevalence and reproducibility of exercise-induced ventricular arrhythmias in the normal subjects and those with definite or suspected cardiovascular disease in each of the age groups.
Volume
37
EXERCISE ARRHYTHMIAS IN NORMAL SUBJECTS-FARIS
TABLE
II
TABLE
Cardiovascular Abnormalities Classified As Having Definite Disease
Observed in the 81 Patients or Suspected Cardiovascular
Age Group 25-34 (no. = 17)
Definite disease Arteriosclerotic heart disease Valvular heart disease Hypertension or hypertensive heart disease Peripheral vascular disease Suspected disease Arteriosclerotic heart disease With exercise S-T changes NonspecIfic S-T and T wave changes Left axis deviation > -‘30° QRS prolongation of >ll set
(Yr)
35-44 (no. = 39) 21
12
z
5 2
: 14 6 0 4
; 18 3 1
110
3 1
5 1
0 1
: 13 1
Results Follow-up: Five hundred forty-three of the 650 subjects completed both maximal treadmill exercise tests with records suitable for arrhythmia analysis. This represented an 85.4 percent follow-up rate. The follow-up rate of subjects classified as normal during the first study was 87 percent (472 of 561); for those with definite or suspected cardiovascular disease it was 80 percent (71 of 89). Ten patients had definite or suspected heart disease in the interval between tests and were reclassified accordingly (Table II). Prevalence of ventricular arrhythmias: The number of subjects studied with two maximal treadmill exercise tests and the prevalence of exercise-induced ventricular arrhythmias are shown in Table III. The subjects are subclassified into a normal group and a group of subjects with definite or sus-
TABLE
Prevalence of Exercise-Induced Ventricular Arrhythmias During Serial Maximal Treadm’ill Exercise Tests in 543 Men Free of Ventricular Arrhythmias at Rest
(vrj 25-34 N CVD 35-44
45-54 N CVD
Prevalence of Arrhythmias
Men (no.)
Test 1
217 17
64(30%) 8(47%)
78(36%) 8(47%)
200 39
64(32%) 21(54%)
76138%) 22(56%)
16(36%) 11(44%)
19(42%) 8(32%)
45 25
Test 2
of Exercise
Serial Maximal
Induced
Treadmill
Ventricular
Exercise
Arrhythmias
petted cardiovascular disease. During the second test exercise-induced ventricular arrhythmias occurred in the normal group in 36 percent (78 of 217) of men aged 25 to 34 years, 38 percent (76 of 200) of those aged 34 to 44 years and 42 percent (19 of 45) of those aged 45 to 54 years. The prevalence rate in these same subjects during the first test was 30 percent (64 of 217), 32 percent (64 of 200) and 36 percent (16 of 45), respectively. These prevalence rates are reasonably close and therefore reproducible. Statistical analysis of these pairs revealed that the absolute increments of 6 percent in each age group were not significant. In the cardiovascular disease group, exercise-induced ventricular arrhythmias were observed during the second test in 47 percent of 25 to 34 year olds, 56 percent of 35 to 44 year olds and 32 percent of 45 to 54 year olds. These prevalence rates were similar to those observed during the first test (47, 54
Age Group (yrj (no.) 25-35 N (217) CVD (17) 35-44 N (200) CVD (39) 45-54 N (45) CVD (25)
Total no.
Observed
During
Tests Men With Arrhythmias
on Test 1
Without Arrhythmias on Test 2
Men With Arrhythmias With Arrhythmias on Test 2
64 8
29(45%) 4(50%)
3;i;y
64 21
27(42%) 5(24%)
16 11
*
*The decreasing prevalence in this subgroup was the result of four subjects who demonstrated ventricular premature complexesat rest as anew finding during the second test and were not considered to have exercise-induced ventriculararrhythmias. CVD = men with definite or suspected cardiovascular disease; N = men with normal clinical findings.
IV
Reproducibility Two
III
Aae Grouo 45-54 (no. = 25)
ET AL.
;;;;7; 00
Total no.* 7% 8
4;;:“03;00
37(58%) 16176%)
77 26
y;;“:“; 00
10162%) 8(73%)
21 12
11(52%) 4(33%)
00
*For the purpose of testing reproducibility of ventricular arrhythmias during exercise, subjects who demonstrated plexes at rest as a new finding on test 2 were included. CVD = men with definite or suspected cardiovascular disease; N = men with normal clinical findings.
March 31, 1976
on Test 2
Without Arrhythmias on Test 1
ventricular
The American Journal of CARDIOLOGY
premature
Volume 37
com-
619
EXERCISE ARRHYTHMIAS IN NORMAL SUBJECTS-FARIS
ET AL.
and 44, respectively). The apparent decrease in prevalence in the 45 to 54 year olds was caused by the exclusion of four persons who at rest demonstrated ventricular premature complexes as a new finding at the time of the second study. As with the first study,8 advancing age was associated with an increasing prevalence of exercise-induced ventricular arrhythmias in both the clinically normal subjects and those with definite or suspected cardiovascular disease. Reproducibility: The number of subjects with exercise-induced ventricular arrhythmias during the first test and the reproducibility of these arrhythmias during repeat testing are shown for each age group in Table IV. The prevalence of exercise-induced ventricular arrhythmias during both tests in the normal subjects was 55 percent in the 25 to 34 year olds, 58 percent in the 35 to 44 year olds and 62 percent in the 45 to 54 year olds. In these same age groups exerciseinduced ventricular arrhythmias were present only in the second test in 59, 58 and 52 percent, respectively (Table IV, columns 5 and 6). Reproducibility of exercise-induced ventricular arrhythmias in the 25 to 34 year olds with definite or suspected cardiovascular disease was similar to that in the normal group (50 percent). In the 35 to 44 and 45 to 54 year old subjects in the cardiovascular disease group, reproducibility during the second test was 76 and 73 percent, respectively. This finding constituted a trend toward greater reproducibility in the older subjects with cardiovascular disease and was statistically significant (P
and Reproducibility
Ventricular
Arrhythmias
of Exercise-Induced
During Maximal
Exercise Testing in Normal Men
JAMES V. FARIS, MD* PAUL L. McHENRY, MD, JOHN W. STEPHEN
FACC
JORDAN, MD N. MORRIS, MD,
Indianapolis.
FACC
Indiana
From the Krannert Institute of Cardiology and the Department of Medicine, Indiana University School of Medicine, Indianapolis, Ind. This study was supported in part by the Herman C. Krannert Fund, Indianapolis, Grants HL-06306. HL05363 and HL-05749 from the National Heart and Lung Institute, National Institutes of Health, Bethesda, Md., the American Heart Association, Dallas, Texas and the Indiana Heart Association, Indianapolis, Ind. * This work was completed during Dr. Faris’s tenure as the John B. Hickam Memorial Fellow of the American Heart Association, Indiana Affiliate, Inc., Indianapolis. Ind. Address for reprints: Paul L. McHenry, MD, Indiana University School of Medicine, 1100 West Michigan St., Indianapolis, Ind. 46202.
The occurrence of ventricular arrhythmias at rest or during ordinary daily activities has been implicated as a risk factor for future coronaryrelated events and sudden death. However, the clinical significance of exercise-induced ventricular arrhythmias remains uncertain. To assess the prevalence and reproducibility of such arrhythmias, two serial maximal treadmill exercise tests were performed in a study population of 543 male Indiana State policemen at an average interval of 2.9 years. Four hundred sixty-two subjects were clinically free of evidence of cardiovascular disease, and 81 had evidence of definite or suspected cardiovascular disease. The prevalence of exercise-induced ventricular arrhythmias during the first test was 30 percent in men aged 25 to 34 years, 32 percent in those aged 35 to 44 years and 38 percent in those aged 45 to 54 years. The prevalence rate in these age groups with repeat testing was 38, 38 and 42 percent, respectively. These differences were not statistically significant. The group with definite or suspected cardiovascular disease had a greater prevalence of exercise-induced ventricular arrhythmias than normal subjects during both tests but the prevalence rate with repeat testing remained constant. The occurrence of exercise-induced ventricular arrhythmias was reproducible in individual subjects during the second test in 55 percent of 25 to 34 year oids, 58 percent of 35 to 44 year oids and 82 percent of 45 to 54 year olds. Thus, individual reproducibility in two consecutive tests was only slightly greater than reproducibility by chance alone. The group with known or suspected cardiovascular disease demonstrated a trend toward greater reproducibility with repeat testing. Exercise-induced ventricular arrhythmias were not reproducible by type or complexity. The marked variability of exercise-induced ventricular arrhythmias during repeat maximal exercise testing in a clinically normal population appears to negate the usefulness of this finding during a single test as a marker of future cardiovascular disease. Nevertheless, subjects whose arrhythmias were reproducible may form a group destined to manifest clinical cardiovascular disease in long-term follow-up studies.
The occurrence of ventricular arrhvthmias at rest or durine ordinarv daily activities has been implicated as a risk factor for fu&e overt heart disease or sudden death.1-6 With the advent of clinical treadmill exercise testing and electrocardiographic recordings during exercise a high incidence rate of exercise-induced ventricular arrhythmias in clinically normal subjects 7,8 has become apparent. The prevalence of exercise-induced ventricular arrhythmias has been reported to be greater in patients with cardiovascular disease than in normal subjects, 8-12 but such arrhythmias have not been documented as a risk factor for future cardiac events in either group. The potential
March 31, 1976
The American Journal of CARDIOLOGY
Volume 37
617
EXERCISE ARRHYTHMIAS
IN NORMAL SUBJECTS-FARIS
ET AL
TABLE I Staging Program for Graded Treadmill Exercise Testing
Staae
Speed (miles/ hour)
Time (min)
I II III IV V VI VII
3
2.0 3.3 3.3 3.3 3.3 3.3 3.3
z 3 3 z
Grade 1%) 3 : 12 15 18 21
clinical implication of exercise-induced ventricular arrhythmias suggested by these reports warrants assessment of their reproducibility to clarify further their significance in a single exercise test.
In 1972 we reported on the prevalence of exerciseinduced ventricular arrhythmias during maximal treadmill exercise testing of 650 male members of the Indiana State Police Force.8 In this study we report on the prevalence of such arrhythmias during a second maximal treadmill exercise test performed an average of 2.9 years later by 543 subjects from the original study group. The reproducibility of exercise-induced ventricular arrhythmias during repeat testing was determined in subjects who had such arrhythmias on their first test. Materials
and Methods
Five hundred forty-three members of the Indiana State Police Force aged 25 to 58 years underwent repeat self-determined maximal treadmill exercise testing an average of 2.9 years (range 1 to 4 years) after the initial test as a part of a continuing cardiovascular evaluation program being conducted at the Indiana University Medical Center. Before each exercise test the subjects had a complete history and physical examination. Posteroanterior and lateral roentgenograms of the chest were obtained as well as routine laboratory studies that included a complete blood count, urinalysis and determination of fasting blood sugar, urea nitrogen and uric acid and serum triglyceride and cholesterol levels. A resting 12 lead electrocardiogram and a continuous 6 minute rhythm strip were recorded before the maximal treadmill exercise test. During the first evaluation subjects manifesting ventricular arrhythmias at rest were excluded so that the true prevalence of exercise-induced ventricular arrhythmias could be defined, Subjects who manifested new ventricular arrhythmias at rest during the second evaluation were not excluded in determining the reproducibility of exercise-induced ventricular arrhythmias during the second test. They were excluded when the prevalence rates of exercise-induced ventricular arrhythmias were determined for the second test so that the data could be compared with those of the first test. Exercise protocol: Our multistage exercise program (Table I), bipolar horizontal lead system and electrode application technique have previously been described.8 All are designed to obtain optimal noise reduction during max-
616
March31,
1976
The American
Journal
of CARDIOLOGY
imal exercise, thus permitting the detection and classification of arrhythmias. An additional bipolar vertical lead system was used in a portion of the second studies to facilitate further the detection and classification of arrhythmias.13 The electrocardiogram was monitored continuously with an oscilloscope, and direct write-outs were recorded at selected intervals and whenever the monitoring physician or technician observed an arrhythmia. The electrocardiographic signal was also recorded continuously on magnetic tape together with an electronically generated time code. All arrhythmias observed during the exercise test were later located on the tape by means of the time code and a complete write-out was obtained. This procedure permitted a thorough analysis of the arrhythmias with respect to frequency, origin and type (extrasystoles per minute, supraventricular versus ventricular, unifocal versus multifoCal). The data were again reviewed for arrhythmias during analog to digital conversion of the electrocardiographic signal in preparation for computer quantitation of the S-T segment response to exercise.l* The QRS configuration was used as the primary determinant of the origin of the recorded arrhythmias, but the recordings were also studied for premature P waves and partial compensatory pauses in an effort to rule out aberrant intraventricular conduction of supraventricular impulses. Two or more consecutive ventricular premature complexes or multifocal ventricular premature complexes were classified as complex exercise-induced ventricular arrhythmias. Ventricular premature complexes were considered multifocal in origin if two distinctly multiform QRS configurations appeared in the same stage of exercise at essentially the same heart rate. The frequency per minute of the ventricular premature complexes was defined as the maximal number of such complexes recorded during any single minute of exercise or during any minute of the 6 minute recovery period. Classification of test subjects: The 543 subjects were classified into three age groups-25 to 34, 35 to 44 and 45 to 54 years-at the time of their first treadmill test. For purposes of comparison in this study they were continued in their initial age group. The clinical and laboratory data for each subject were reviewed for evidence of cardiovascular disease. At the time of the first evaluation subjects were classified as having definite cardiovascular disease if they had (1) classic exertional angina, (2) a previous documented myocardial infarction, (3) a previous episode of chest pain consistent with myocardial ischemia accompanied by serial ST-T wave changes, (4) evidence of valvular heart disease, (5) persistent resting systolic blood pressure greater than 160 mm Hg or diastolic pressure greater than 96 mm Hg, or (6) symptomatic peripheral vascular or cerebrovascular disease. A diagnosis of “suspected” cardiovascular disease was made if they had (1) experienced one or more episodes of chest pain consistent with myocardial ischemia but without associated electrocardiographic or serum enzyme changes, (2) a positive computer-quantitated S-T segment index in response to maximal exercise,14 or (3) any abnormality of the resting electrocardiogram without other clinical evidence of heart disease (Table II). The subjects were reclassified after the second evaluation if they manifested any of these criteria as a serial change. A statistical analysis was then made of the observed prevalence and reproducibility of exercise-induced ventricular arrhythmias in the normal subjects and those with definite or suspected cardiovascular disease in each of the age groups.
Volume
37
EXERCISE ARRHYTHMIAS IN NORMAL SUBJECTS-FARIS
TABLE
II
TABLE
Cardiovascular Abnormalities Classified As Having Definite Disease
Observed in the 81 Patients or Suspected Cardiovascular
Age Group 25-34 (no. = 17)
Definite disease Arteriosclerotic heart disease Valvular heart disease Hypertension or hypertensive heart disease Peripheral vascular disease Suspected disease Arteriosclerotic heart disease With exercise S-T changes NonspecIfic S-T and T wave changes Left axis deviation > -‘30° QRS prolongation of >ll set
(Yr)
35-44 (no. = 39) 21
12
z
5 2
: 14 6 0 4
; 18 3 1
110
3 1
5 1
0 1
: 13 1
Results Follow-up: Five hundred forty-three of the 650 subjects completed both maximal treadmill exercise tests with records suitable for arrhythmia analysis. This represented an 85.4 percent follow-up rate. The follow-up rate of subjects classified as normal during the first study was 87 percent (472 of 561); for those with definite or suspected cardiovascular disease it was 80 percent (71 of 89). Ten patients had definite or suspected heart disease in the interval between tests and were reclassified accordingly (Table II). Prevalence of ventricular arrhythmias: The number of subjects studied with two maximal treadmill exercise tests and the prevalence of exercise-induced ventricular arrhythmias are shown in Table III. The subjects are subclassified into a normal group and a group of subjects with definite or sus-
TABLE
Prevalence of Exercise-Induced Ventricular Arrhythmias During Serial Maximal Treadm’ill Exercise Tests in 543 Men Free of Ventricular Arrhythmias at Rest
(vrj 25-34 N CVD 35-44
45-54 N CVD
Prevalence of Arrhythmias
Men (no.)
Test 1
217 17
64(30%) 8(47%)
78(36%) 8(47%)
200 39
64(32%) 21(54%)
76138%) 22(56%)
16(36%) 11(44%)
19(42%) 8(32%)
45 25
Test 2
of Exercise
Serial Maximal
Induced
Treadmill
Ventricular
Exercise
Arrhythmias
petted cardiovascular disease. During the second test exercise-induced ventricular arrhythmias occurred in the normal group in 36 percent (78 of 217) of men aged 25 to 34 years, 38 percent (76 of 200) of those aged 34 to 44 years and 42 percent (19 of 45) of those aged 45 to 54 years. The prevalence rate in these same subjects during the first test was 30 percent (64 of 217), 32 percent (64 of 200) and 36 percent (16 of 45), respectively. These prevalence rates are reasonably close and therefore reproducible. Statistical analysis of these pairs revealed that the absolute increments of 6 percent in each age group were not significant. In the cardiovascular disease group, exercise-induced ventricular arrhythmias were observed during the second test in 47 percent of 25 to 34 year olds, 56 percent of 35 to 44 year olds and 32 percent of 45 to 54 year olds. These prevalence rates were similar to those observed during the first test (47, 54
Age Group (yrj (no.) 25-35 N (217) CVD (17) 35-44 N (200) CVD (39) 45-54 N (45) CVD (25)
Total no.
Observed
During
Tests Men With Arrhythmias
on Test 1
Without Arrhythmias on Test 2
Men With Arrhythmias With Arrhythmias on Test 2
64 8
29(45%) 4(50%)
3;i;y
64 21
27(42%) 5(24%)
16 11
*
*The decreasing prevalence in this subgroup was the result of four subjects who demonstrated ventricular premature complexesat rest as anew finding during the second test and were not considered to have exercise-induced ventriculararrhythmias. CVD = men with definite or suspected cardiovascular disease; N = men with normal clinical findings.
IV
Reproducibility Two
III
Aae Grouo 45-54 (no. = 25)
ET AL.
;;;;7; 00
Total no.* 7% 8
4;;:“03;00
37(58%) 16176%)
77 26
y;;“:“; 00
10162%) 8(73%)
21 12
11(52%) 4(33%)
00
*For the purpose of testing reproducibility of ventricular arrhythmias during exercise, subjects who demonstrated plexes at rest as a new finding on test 2 were included. CVD = men with definite or suspected cardiovascular disease; N = men with normal clinical findings.
March 31, 1976
on Test 2
Without Arrhythmias on Test 1
ventricular
The American Journal of CARDIOLOGY
premature
Volume 37
com-
619
EXERCISE ARRHYTHMIAS IN NORMAL SUBJECTS-FARIS
ET AL.
and 44, respectively). The apparent decrease in prevalence in the 45 to 54 year olds was caused by the exclusion of four persons who at rest demonstrated ventricular premature complexes as a new finding at the time of the second study. As with the first study,8 advancing age was associated with an increasing prevalence of exercise-induced ventricular arrhythmias in both the clinically normal subjects and those with definite or suspected cardiovascular disease. Reproducibility: The number of subjects with exercise-induced ventricular arrhythmias during the first test and the reproducibility of these arrhythmias during repeat testing are shown for each age group in Table IV. The prevalence of exercise-induced ventricular arrhythmias during both tests in the normal subjects was 55 percent in the 25 to 34 year olds, 58 percent in the 35 to 44 year olds and 62 percent in the 45 to 54 year olds. In these same age groups exerciseinduced ventricular arrhythmias were present only in the second test in 59, 58 and 52 percent, respectively (Table IV, columns 5 and 6). Reproducibility of exercise-induced ventricular arrhythmias in the 25 to 34 year olds with definite or suspected cardiovascular disease was similar to that in the normal group (50 percent). In the 35 to 44 and 45 to 54 year old subjects in the cardiovascular disease group, reproducibility during the second test was 76 and 73 percent, respectively. This finding constituted a trend toward greater reproducibility in the older subjects with cardiovascular disease and was statistically significant (P
