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The relation of “Silent” T wave inversion to cardiovascular disease in an epidemiologic study
The Relation of "Silent" T Wave Inversion to Cardiovascular Disease in an Epidemiologic Study
LEON D. OSTRANDER, Jr., MD
Ann Arbor, Michigan
From the Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Mich. This study was supported by Program Project Grant HE-06378 from the National Heart Institute, National Institutes of Health, U. S. Public Health Service. Manuscript received April 10, 1969, accepted May 26, 1969. Address for reprints: Leon D, Ostrander, Jr., MD, Department of Epiderniology, School of Public Health, The University of Michigan, Ann Arbor, Mich. 48104.
VOLUME 25, MARCH 1970
Forty-seven adults (24 men and 23 women), approximately 1 percent of the examined population of Tecumseh, Mich. had nonspecific T wave inversion unassociated with symptoms or physical signs of heart disease or administration of drugs. They had a higher age-specific prevalence of obesity, hypertension, hypercholesterolemia and hyperglycemia than the total examined Tecumseh population. Individuals with silent T wave inversion also had a significantly higher mortality than expected for a representa. tive sample of Tecumseh participants of similar age and sex. The physiologic abnormalities and course of these 47 persons suggests that even without other symptoms or signs T wave inversions is usually an indication of hypertensive or coronary heart disease. T wave inversion may be a benign finding in the occasional individual who remains free of overt disease and has no abnormalities predisposing to heart disease.
The recognition of electrocardiographic abnormalities characteristic of myocardial infarction permits the physician to make a reliable diagnosis even if the patient recalls no symptoms. Similarly, when a patient has typical symptoms or signs of heart disease, a normal electrocardiogram does not detract from the diagnosis, but nonspecific electrocardiographic abnormalities are accepted as additional evidence of disease. Since electrocardiograms are recorded almost routinely from adults with a variety of noncardiac diseases and from persons who undergo periodic health examinations, nonspecific abnormalities are frequently observed in the tracings of persons without symptoms or other signs of heart disease. Some electrocardiographic abnormalities such as intraventricular block or high amplitude QR,S complexes at least suggest an anatomic defect; however, the most common nonspecific findings, S-T segment depression or T wave inversion, are a disquieting hint of latent disease which the physician can neither confirm nor dismiss. T wave inversion secondary to abnormalities in ventricular activation presents no problem. Some primary T wave changes have such characteristic features that their origin is reasonably certain. The contour of the digitalis-altered T wave is a familiar example. T wave inversion in the right precordial leads recorded from healthy adolescents or young adults, the "juvenile pattern," has not been associated with disease. 1~ Electrolyte disturbances, 4 drugs, 5 intracranial lesions,6 hyperventilation,7,s recent ingestion of food or glucose9,1° and ethnic origin3,~ are some factors responsible for abnormal T waves; however, most changes observed in the electrocardiograms of asymptomatic persons cannot be attributed to such specific causes.
325
OSTRANDER
In clinical practice nonspecific T wave abnormalities are logically considered a sign of myocardial disease because they are so prevalent among people with other evidence of heart disease. The experience of several insurance companies, reviewed by Blackburn and Parlin, ~ indicates an excess mortality among persons with T wave abnormalities. Kannel et al. ~s reported that T wave inversion was an unfavorable prognostic sign among participants in the Framingham epidemiologic study. On the other hand, Blackburn et al. 14 reported a similar prevalence rate and age gradient for T wave inversion among men in Italy and the United States who differed markedly in their frequency of coronary heart disease. It is possible, then, that some T wave abnormalities are a benign manifestation of aging and do not signify myocardial disease. The lability of even fairly marked T wave changes further complicates their interpretation. 15
Methods The community of Tecumseh, Mich. is the site of a prospective epidemiologic study of factors that may affect the health of the residents. 1° Nearly 90 percent of the inhabitants have participated in each of two series of examinations. During 1959 and 1960, 4,678 persons over age 20 had electrocardiograms taken as part of their comprehensive examinations. A second series of examinations was conducted from 1962 to 1965. The interval between examinations ranged from 20 to 72 months for individuals (median 47 months). The period between examinations ranged from 40 to 56 months for 80 percent of the cohort examined twice. 15 Each examinatian included a medical history, thorough physical examination, chest roentgenogram and serum cholesterol and blood glucose determinations. A majority of participants underwent venipuncture one hour after administration of glucose (100 g). It was necessary to record electrocardiograms soon after the participants arrived at the clinic, without regard for previous meals. During the first series of examinations electrocardiograms were sometimes recorded after the ingestion of the oral glucose challenge. Electrocardiograms were classified according to the system of Blackburn et al. 17 Overweight (based on a relative weight index), hypertension and hypercholesterolemia were arbitrarily defined according to the upper quintile of the age- and sex-specific distribution of the variables. Hyperglycemia was similarly defined, but the type of test (casual or postchallenge) was taken into account in the assignment. All patients known to have diabetes were classified in the upper quintile of distributions for blood glucose; thus, 24 percent of women and 22 percent of men past 40 years we:re considered hyperglycemic. S Persons were included in the study population if (1) their electrocardiograms fulfilled the criteria for the 5-2 classification of the Minnesota code and did not show QRS changes of infarction, intraventricular block or ventricular hypertrophy; and (2) if they had no other evidence of heart disease and were taking no
326
TABLE I Prevalence of T wave Inversion Without Other Manifestations of Heart Disease Among Tecumseh Participants Age groups (yr) Number examined Number with T wave inversion Percent with T wave inversion
20-29 30-39 40-49 50-59 60-69 70+ 1035 1381 941 658 374 289 2
4
5
13
15
8
0.2
0.3
0.5
2.0
4.0
2.8
drugs known to alter T waves. 17 The 5-2 classification includes primary T wave inversion greater than 1 mm but less than 5 mm in amplitude in leads that record left ventricular potentials. Although ingestion of food9 or glucose 1° sometimes affects the T waves, the changes are rarely of this magnitude. 1° A few young participants with inverted T waves in several of the chest leads were excluded from the analysis because the tracings were characteristic of the "juvenile pattern". 1,2
Results Prevalence: Of the 4,678 examined persons past 20 years of age in 1959 or 1960, 47 participants (24 men and 23 women; 1 percent of the total) had inverted T waves without other evidence of heart disease (Table I). The prevalence rate ranged from 0.2 percent for subjects aged 20 to 29 years to 4.0 percent for subjects aged 60 to 69 years. Risk factors: Obesity, systolic and diastolic hy-
pertension, hyperchole~terolemia and hyperglycemia were more prevalent among persons with T wave inversion than in the total examined population (Table II). Seven of the 47 persons had no physiologic abnormalities. The differences were significant for obesity and high blood pressure of either type. These 47 participants included a slightly lower proportion of cigarette smokers than would be expected in a representative Tecumseh population sample with similar age and sex characteristics. Reexamination: Six persons (13 percent) with inverted T waves remained free of cardiac symptoms or signs and had normal electrocardiograms at the time of the second examination (Table III). Seventeen (36 percent) continued to have inverted T waves on TABLE II Frequency of Physiologic Abnormalities Among Forty-Seven Persons with T wave Inversion in Tecumseh Overweight (46 determinations) Systolic hypertension Diastolic hypertension Hypercholesterolemia(43 determinations) Hyperglycemia (43 determinations)
15 20 17 12 15
33%* 42%t 36%t 28% 35%~
* Significant at 5 percent level. t Significant at 1 percent level. ~: Not significant because of higher expected proportion of hyperglycemia (23%) and smaller number of determinations.
The American Journal of CARDIOLOGY
"SILENT" T WAVE INVERSION AND CARDIOVASCULAR DISEASE
between examinations among these 17 participants, but most had a decrease in diastolic blood pressure (Table IV). The 11 survivors who were not reexamined were slightly younger than the mean age for the entire group. They had the lowest prevalence of obesity and hyperglycemia of any subgroup (Table III) and a high frequency of hypertension and hypercholesterolemia. The 1 surviving man who experienced symptoms o f angina pectoris was obese, hypertensive and hyperglycemic; his age was near the group mean. Mortality: The mean age of the 7 men and 5 women who died was 70 years, the oldest of any subgroup (Table III). Most of the fatalities were attri, buted to cardiovascular disease. There were five myocardial infarctions, two strokes and one renal failure. The four noncardiac deaths were caused by accident (2 subjects), cancer (1 subject) and undetermined factors (1 subject). The prevalence of hypertension and hypercholesterolemia among those who died was similar to that for t h e entire group. Obesity was less frequent, but half of those who died had prior hyperglycemia. Five deaths would have been expected among a representative sample of Tecumseh participants similar in age and sex to the persons with inverted T waves. The 12 deaths observed among these 47 participants indicates a significantly increased mortality for this group (Table V).
TABLE III Characteristics of Participants at the Time of First Examination According to Their Status at the Time of Reexamination, Death or Withdrawal Sex no. ECG became normal No change in
status New CHD
Death Withdrawal from s t u d y
Total
% Age M F RW* SBP* DBP* SC* BG*
6
13 47
2 4
67
67
67
33
50
17 1 12
36 55 2 58 26 70
9 8 24 1 0 100 7 5 25
29 100 42
12 100 36
18 0 30
29 100 50
45 42
55 36
44 28
11 35
11 23 53 5 6 47 100 57 24 23
20 33
* Percent with high values. Age - - mean age; BG = blood glucose elevation; CHD = coronary heart disease; DBP = diastolic hypertension; RW = high relative weight; SBP = systolic hypertension; SC = serum cholesterol elevation.
reexamination but remained free of other evidence of heart disease. Angina pectoris developed in 1 man, but his electrocardiogram became normal. Twelve persons (26 percent) died from various causes before they could be reexamined, and 11 (23 percent) were alive but either refused reexamination or had moved from the community. The mean age of the 4 women and 2 men whose electrocardiograms became normal was 47 years (range 24 to 63 years; Table I I I ) . Four were obese, 4 had systolic and 4 diastolic hypertension. Three had hyperglycemia and 2 hypercholesterolemia. Between examinations all lost weight. Three had lower systolic blood pressure but 4 had higher diastolic blood pressure (Table IV). However, since the increases in diastolic blood pressure were trivial and the reductions substantial, the mean diastolic pressure for this group was lower on the second examination. The status of 9 men and 8 women (mean age 55 years) did not change (Table III). The proportion of persons with obesity, hypertension, hypercholesterolemia or hyperglycemia was lower in this segment than among the total group with inverted T waves. There was little change in weight or systolic blood pressure
Discussion The characteristics and course of 47 persons who were identified from nearly the entire adult population of Tecumseh permit a more valid assessment of the clinical significance of isolated T wave inversion among white Americans than studies of less representative populations. The progressively higher prevalence of silent T wave inversion among successive age groups is consistent with an acquired characteristic. The lower mean age of the persons whose electrocardiograms reverted to normal and the previously reported lability of all T wave findings in this population 1~ suggest that T waves may fluctuate between normal and abnormal for years before they become persistently invertedi
TABLE IV Changes in Weight and Blood Pressure Among Participants Examined Twice Systolic Blood Pressure
Weight
Improved Sta ble Worse
no.
increase
Decrease
Mean Change (kg)
6 17" 1
0 7 1
6 9 0
--6.5 --0.6 -I-1.0
increase 3 11 0
Diastolic Blood Pressure
Decrease
Mean Change (mm Hg)
Increase
Decrease
Mean Change (mm Hg)
3 5 1
--0.7 -t-0.2 --44.0
4 5 0
2 11 1
--5.7 ---4.3 --20.0
* One in each category did not change.
VOLUME 25, MARCH 1970
327
OSTRANDER TABLE V Observed and Expected Deaths Among Persons With T Wave Inversion in Tecumseh Deaths Age
no.
Expected*
20-49 50-59 60-69 70-79 80+ Total
11 13 15 4 4 47.0
0.1 0.6 1.9 1.1 1.3 5.0
Observed 0.0 3.0 2.0 3.0 4.0 12.0t
* Based on age- and sex-specific death rates during period of observation. t Difference significant at 0.5 percent level.
High blood pressure was the most frequent physiologic abnormality among the total group. Hypertension substantially increases the risk of coronary heart disease, but it is also the most frequent cause of left ventricular hypertrophy. Although high amplitude QRS complexes in specific leads are required for the diagnosis of left ventricular enlargement according to the usual criteria, QR,S amplitudes are frequently insufficient for diagnosis in persons who might be expected to have enlargement, is In many instances T
wave inversion is the only electrocardiographic clue to clinically suspected hypertrophy. Age seems to be the most important short-term prognostic factor. Persons whose electrocardiograms reverted to normal between examinations had a high prevalence of physiologic abnormalities but were younger than individuals in the other groups. Persons who died were older than those in other groups, but they did not differ appreciably from the total group in prevalence of other risk factors. Clinical implications: In the Tecumseh population T wave inversion appears to be a sign of hypertensive or atherosclerotic heart disease in most instances. Persons with this electrocardiographic abnormality had a high prevalence of conditions that predispose to coronary heart disease and an excess mortality that was predominantly due to cardiovascular disease. Nevertheless, the status of 6 of the 7 participants who had no overt physiologic abnormalities remained stable. Perhaps T wave inversion is a benign condition in certain individuals who have no other evidence of heart disease during several years of observation and no physiologic abnormalities that predispose to heart disease. Goldman 19 has warned against overdiagnosis of heart disease among such persons.
References 1. Littman D." Abnormal electrocardiograms in the absence of demonstrable heart disease. Amer J Med 5:337-350, 1948 2. Gottschalk CW, Craige E: A comparison of precordial ST and T waves in the electrocardiograms of 600 healthy young negro and white adults. Southern Med J 49:453-457, 1956 3. Wasserburger RH: Observation on the "juvenile pattern" of adult Negro males. Amer J Med 18:428-437, 1955 4. Merrill AJ: The significance of the electrocardiogram in electrolyte disturbances. Amer Heart J 43:634-639, 1952 5. Ban TA" Electrocardiographic changes induced by phenothiazine drugs. Amer Heart J 70:575-576, 1965 6. Hirsch C: Electrocardiographic changes in subarachnoid hemorrhage, meningitis and intracranial space occupying lesions. Brit Heart J 26:785-793, 1964 7. Wasserburger RH, Lorenz TH" The effect of hyperventilation and probanthine on isolated RST segment and T wave abnormalities. Amer Heart J 51:666-683, 1956 8. Kemp GL, Ellestad MH= The significance of hyperventilation and orthostatic T wave changes on the electrocardiogram. Arch Intern Med (Chicago) 121:518-523, 1968 9. Simonson E, Keys A: The effect of an ordinary meal on the electrocardiogrammnormal standards in middle aged men and women. Circulation 1:1000-1005, ~1950 10. Ostrander LD Jr, Weinstein B J: Electrocardiogrhphic
328
11. 12. 13. 14. 15. 16.
17. 18. 19.
changes after glucose ingestion. Circulation 30:67-76, 1964 Epstein FH, Pollack AA, Ostrander LD Jr: An electrocardiographic survey in Peru. Amer J Med Sci 247:687-693, 1964 Blackburn H, Parlin RW" Antecedents of disease. Insurance mortality statistics. Ann NY Acad Sci 134:965-1017, 1966 Kannel MB, Kagan A, Dawber TR, et ah The epidemiology of coronary heart disease. Geriatrics 17:675-690, 1962 Blackburn H, Vasquez CL, Keys A: The aging electrocardiogram. Amer J Cardiol 20:618-627, 1967 Ostrander LD Jr: Serial electrocardiographic findings in a prospective epidemiologic study. Circulation 34:1069-1080, 1966 Francis T Jr, Epstein FH" Epidemiologic research in a total natural community, Tecumseh, Michigan, in International Conference on Comparability in Epidemiologic Studies, International Epidemiological Association (Acheson RM, ed). Milbank Memorial Fund Quarterly 43 (no. 2, Part 2): 333-342, 1965 Blackburn H, Keys A, Simonson E, et ah The electrocardiogram in population studies: a classification system. Circulation 21:1160-1175, 1960 Ostrander LD Jr" Epidemiologic study of the electrocardiographic diagnosis of left ventricular hypertrophy. Circulation 33:270-282, 1966 Goldman M J: Normal variants in electrocardiograms leading to cardiac invalidism. Amer Heart J 59:71-77, 1960
The American Journal of CARDIOLOGY
LEON D. OSTRANDER, Jr., MD
Ann Arbor, Michigan
From the Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Mich. This study was supported by Program Project Grant HE-06378 from the National Heart Institute, National Institutes of Health, U. S. Public Health Service. Manuscript received April 10, 1969, accepted May 26, 1969. Address for reprints: Leon D, Ostrander, Jr., MD, Department of Epiderniology, School of Public Health, The University of Michigan, Ann Arbor, Mich. 48104.
VOLUME 25, MARCH 1970
Forty-seven adults (24 men and 23 women), approximately 1 percent of the examined population of Tecumseh, Mich. had nonspecific T wave inversion unassociated with symptoms or physical signs of heart disease or administration of drugs. They had a higher age-specific prevalence of obesity, hypertension, hypercholesterolemia and hyperglycemia than the total examined Tecumseh population. Individuals with silent T wave inversion also had a significantly higher mortality than expected for a representa. tive sample of Tecumseh participants of similar age and sex. The physiologic abnormalities and course of these 47 persons suggests that even without other symptoms or signs T wave inversions is usually an indication of hypertensive or coronary heart disease. T wave inversion may be a benign finding in the occasional individual who remains free of overt disease and has no abnormalities predisposing to heart disease.
The recognition of electrocardiographic abnormalities characteristic of myocardial infarction permits the physician to make a reliable diagnosis even if the patient recalls no symptoms. Similarly, when a patient has typical symptoms or signs of heart disease, a normal electrocardiogram does not detract from the diagnosis, but nonspecific electrocardiographic abnormalities are accepted as additional evidence of disease. Since electrocardiograms are recorded almost routinely from adults with a variety of noncardiac diseases and from persons who undergo periodic health examinations, nonspecific abnormalities are frequently observed in the tracings of persons without symptoms or other signs of heart disease. Some electrocardiographic abnormalities such as intraventricular block or high amplitude QR,S complexes at least suggest an anatomic defect; however, the most common nonspecific findings, S-T segment depression or T wave inversion, are a disquieting hint of latent disease which the physician can neither confirm nor dismiss. T wave inversion secondary to abnormalities in ventricular activation presents no problem. Some primary T wave changes have such characteristic features that their origin is reasonably certain. The contour of the digitalis-altered T wave is a familiar example. T wave inversion in the right precordial leads recorded from healthy adolescents or young adults, the "juvenile pattern," has not been associated with disease. 1~ Electrolyte disturbances, 4 drugs, 5 intracranial lesions,6 hyperventilation,7,s recent ingestion of food or glucose9,1° and ethnic origin3,~ are some factors responsible for abnormal T waves; however, most changes observed in the electrocardiograms of asymptomatic persons cannot be attributed to such specific causes.
325
OSTRANDER
In clinical practice nonspecific T wave abnormalities are logically considered a sign of myocardial disease because they are so prevalent among people with other evidence of heart disease. The experience of several insurance companies, reviewed by Blackburn and Parlin, ~ indicates an excess mortality among persons with T wave abnormalities. Kannel et al. ~s reported that T wave inversion was an unfavorable prognostic sign among participants in the Framingham epidemiologic study. On the other hand, Blackburn et al. 14 reported a similar prevalence rate and age gradient for T wave inversion among men in Italy and the United States who differed markedly in their frequency of coronary heart disease. It is possible, then, that some T wave abnormalities are a benign manifestation of aging and do not signify myocardial disease. The lability of even fairly marked T wave changes further complicates their interpretation. 15
Methods The community of Tecumseh, Mich. is the site of a prospective epidemiologic study of factors that may affect the health of the residents. 1° Nearly 90 percent of the inhabitants have participated in each of two series of examinations. During 1959 and 1960, 4,678 persons over age 20 had electrocardiograms taken as part of their comprehensive examinations. A second series of examinations was conducted from 1962 to 1965. The interval between examinations ranged from 20 to 72 months for individuals (median 47 months). The period between examinations ranged from 40 to 56 months for 80 percent of the cohort examined twice. 15 Each examinatian included a medical history, thorough physical examination, chest roentgenogram and serum cholesterol and blood glucose determinations. A majority of participants underwent venipuncture one hour after administration of glucose (100 g). It was necessary to record electrocardiograms soon after the participants arrived at the clinic, without regard for previous meals. During the first series of examinations electrocardiograms were sometimes recorded after the ingestion of the oral glucose challenge. Electrocardiograms were classified according to the system of Blackburn et al. 17 Overweight (based on a relative weight index), hypertension and hypercholesterolemia were arbitrarily defined according to the upper quintile of the age- and sex-specific distribution of the variables. Hyperglycemia was similarly defined, but the type of test (casual or postchallenge) was taken into account in the assignment. All patients known to have diabetes were classified in the upper quintile of distributions for blood glucose; thus, 24 percent of women and 22 percent of men past 40 years we:re considered hyperglycemic. S Persons were included in the study population if (1) their electrocardiograms fulfilled the criteria for the 5-2 classification of the Minnesota code and did not show QRS changes of infarction, intraventricular block or ventricular hypertrophy; and (2) if they had no other evidence of heart disease and were taking no
326
TABLE I Prevalence of T wave Inversion Without Other Manifestations of Heart Disease Among Tecumseh Participants Age groups (yr) Number examined Number with T wave inversion Percent with T wave inversion
20-29 30-39 40-49 50-59 60-69 70+ 1035 1381 941 658 374 289 2
4
5
13
15
8
0.2
0.3
0.5
2.0
4.0
2.8
drugs known to alter T waves. 17 The 5-2 classification includes primary T wave inversion greater than 1 mm but less than 5 mm in amplitude in leads that record left ventricular potentials. Although ingestion of food9 or glucose 1° sometimes affects the T waves, the changes are rarely of this magnitude. 1° A few young participants with inverted T waves in several of the chest leads were excluded from the analysis because the tracings were characteristic of the "juvenile pattern". 1,2
Results Prevalence: Of the 4,678 examined persons past 20 years of age in 1959 or 1960, 47 participants (24 men and 23 women; 1 percent of the total) had inverted T waves without other evidence of heart disease (Table I). The prevalence rate ranged from 0.2 percent for subjects aged 20 to 29 years to 4.0 percent for subjects aged 60 to 69 years. Risk factors: Obesity, systolic and diastolic hy-
pertension, hyperchole~terolemia and hyperglycemia were more prevalent among persons with T wave inversion than in the total examined population (Table II). Seven of the 47 persons had no physiologic abnormalities. The differences were significant for obesity and high blood pressure of either type. These 47 participants included a slightly lower proportion of cigarette smokers than would be expected in a representative Tecumseh population sample with similar age and sex characteristics. Reexamination: Six persons (13 percent) with inverted T waves remained free of cardiac symptoms or signs and had normal electrocardiograms at the time of the second examination (Table III). Seventeen (36 percent) continued to have inverted T waves on TABLE II Frequency of Physiologic Abnormalities Among Forty-Seven Persons with T wave Inversion in Tecumseh Overweight (46 determinations) Systolic hypertension Diastolic hypertension Hypercholesterolemia(43 determinations) Hyperglycemia (43 determinations)
15 20 17 12 15
33%* 42%t 36%t 28% 35%~
* Significant at 5 percent level. t Significant at 1 percent level. ~: Not significant because of higher expected proportion of hyperglycemia (23%) and smaller number of determinations.
The American Journal of CARDIOLOGY
"SILENT" T WAVE INVERSION AND CARDIOVASCULAR DISEASE
between examinations among these 17 participants, but most had a decrease in diastolic blood pressure (Table IV). The 11 survivors who were not reexamined were slightly younger than the mean age for the entire group. They had the lowest prevalence of obesity and hyperglycemia of any subgroup (Table III) and a high frequency of hypertension and hypercholesterolemia. The 1 surviving man who experienced symptoms o f angina pectoris was obese, hypertensive and hyperglycemic; his age was near the group mean. Mortality: The mean age of the 7 men and 5 women who died was 70 years, the oldest of any subgroup (Table III). Most of the fatalities were attri, buted to cardiovascular disease. There were five myocardial infarctions, two strokes and one renal failure. The four noncardiac deaths were caused by accident (2 subjects), cancer (1 subject) and undetermined factors (1 subject). The prevalence of hypertension and hypercholesterolemia among those who died was similar to that for t h e entire group. Obesity was less frequent, but half of those who died had prior hyperglycemia. Five deaths would have been expected among a representative sample of Tecumseh participants similar in age and sex to the persons with inverted T waves. The 12 deaths observed among these 47 participants indicates a significantly increased mortality for this group (Table V).
TABLE III Characteristics of Participants at the Time of First Examination According to Their Status at the Time of Reexamination, Death or Withdrawal Sex no. ECG became normal No change in
status New CHD
Death Withdrawal from s t u d y
Total
% Age M F RW* SBP* DBP* SC* BG*
6
13 47
2 4
67
67
67
33
50
17 1 12
36 55 2 58 26 70
9 8 24 1 0 100 7 5 25
29 100 42
12 100 36
18 0 30
29 100 50
45 42
55 36
44 28
11 35
11 23 53 5 6 47 100 57 24 23
20 33
* Percent with high values. Age - - mean age; BG = blood glucose elevation; CHD = coronary heart disease; DBP = diastolic hypertension; RW = high relative weight; SBP = systolic hypertension; SC = serum cholesterol elevation.
reexamination but remained free of other evidence of heart disease. Angina pectoris developed in 1 man, but his electrocardiogram became normal. Twelve persons (26 percent) died from various causes before they could be reexamined, and 11 (23 percent) were alive but either refused reexamination or had moved from the community. The mean age of the 4 women and 2 men whose electrocardiograms became normal was 47 years (range 24 to 63 years; Table I I I ) . Four were obese, 4 had systolic and 4 diastolic hypertension. Three had hyperglycemia and 2 hypercholesterolemia. Between examinations all lost weight. Three had lower systolic blood pressure but 4 had higher diastolic blood pressure (Table IV). However, since the increases in diastolic blood pressure were trivial and the reductions substantial, the mean diastolic pressure for this group was lower on the second examination. The status of 9 men and 8 women (mean age 55 years) did not change (Table III). The proportion of persons with obesity, hypertension, hypercholesterolemia or hyperglycemia was lower in this segment than among the total group with inverted T waves. There was little change in weight or systolic blood pressure
Discussion The characteristics and course of 47 persons who were identified from nearly the entire adult population of Tecumseh permit a more valid assessment of the clinical significance of isolated T wave inversion among white Americans than studies of less representative populations. The progressively higher prevalence of silent T wave inversion among successive age groups is consistent with an acquired characteristic. The lower mean age of the persons whose electrocardiograms reverted to normal and the previously reported lability of all T wave findings in this population 1~ suggest that T waves may fluctuate between normal and abnormal for years before they become persistently invertedi
TABLE IV Changes in Weight and Blood Pressure Among Participants Examined Twice Systolic Blood Pressure
Weight
Improved Sta ble Worse
no.
increase
Decrease
Mean Change (kg)
6 17" 1
0 7 1
6 9 0
--6.5 --0.6 -I-1.0
increase 3 11 0
Diastolic Blood Pressure
Decrease
Mean Change (mm Hg)
Increase
Decrease
Mean Change (mm Hg)
3 5 1
--0.7 -t-0.2 --44.0
4 5 0
2 11 1
--5.7 ---4.3 --20.0
* One in each category did not change.
VOLUME 25, MARCH 1970
327
OSTRANDER TABLE V Observed and Expected Deaths Among Persons With T Wave Inversion in Tecumseh Deaths Age
no.
Expected*
20-49 50-59 60-69 70-79 80+ Total
11 13 15 4 4 47.0
0.1 0.6 1.9 1.1 1.3 5.0
Observed 0.0 3.0 2.0 3.0 4.0 12.0t
* Based on age- and sex-specific death rates during period of observation. t Difference significant at 0.5 percent level.
High blood pressure was the most frequent physiologic abnormality among the total group. Hypertension substantially increases the risk of coronary heart disease, but it is also the most frequent cause of left ventricular hypertrophy. Although high amplitude QRS complexes in specific leads are required for the diagnosis of left ventricular enlargement according to the usual criteria, QR,S amplitudes are frequently insufficient for diagnosis in persons who might be expected to have enlargement, is In many instances T
wave inversion is the only electrocardiographic clue to clinically suspected hypertrophy. Age seems to be the most important short-term prognostic factor. Persons whose electrocardiograms reverted to normal between examinations had a high prevalence of physiologic abnormalities but were younger than individuals in the other groups. Persons who died were older than those in other groups, but they did not differ appreciably from the total group in prevalence of other risk factors. Clinical implications: In the Tecumseh population T wave inversion appears to be a sign of hypertensive or atherosclerotic heart disease in most instances. Persons with this electrocardiographic abnormality had a high prevalence of conditions that predispose to coronary heart disease and an excess mortality that was predominantly due to cardiovascular disease. Nevertheless, the status of 6 of the 7 participants who had no overt physiologic abnormalities remained stable. Perhaps T wave inversion is a benign condition in certain individuals who have no other evidence of heart disease during several years of observation and no physiologic abnormalities that predispose to heart disease. Goldman 19 has warned against overdiagnosis of heart disease among such persons.
References 1. Littman D." Abnormal electrocardiograms in the absence of demonstrable heart disease. Amer J Med 5:337-350, 1948 2. Gottschalk CW, Craige E: A comparison of precordial ST and T waves in the electrocardiograms of 600 healthy young negro and white adults. Southern Med J 49:453-457, 1956 3. Wasserburger RH: Observation on the "juvenile pattern" of adult Negro males. Amer J Med 18:428-437, 1955 4. Merrill AJ: The significance of the electrocardiogram in electrolyte disturbances. Amer Heart J 43:634-639, 1952 5. Ban TA" Electrocardiographic changes induced by phenothiazine drugs. Amer Heart J 70:575-576, 1965 6. Hirsch C: Electrocardiographic changes in subarachnoid hemorrhage, meningitis and intracranial space occupying lesions. Brit Heart J 26:785-793, 1964 7. Wasserburger RH, Lorenz TH" The effect of hyperventilation and probanthine on isolated RST segment and T wave abnormalities. Amer Heart J 51:666-683, 1956 8. Kemp GL, Ellestad MH= The significance of hyperventilation and orthostatic T wave changes on the electrocardiogram. Arch Intern Med (Chicago) 121:518-523, 1968 9. Simonson E, Keys A: The effect of an ordinary meal on the electrocardiogrammnormal standards in middle aged men and women. Circulation 1:1000-1005, ~1950 10. Ostrander LD Jr, Weinstein B J: Electrocardiogrhphic
328
11. 12. 13. 14. 15. 16.
17. 18. 19.
changes after glucose ingestion. Circulation 30:67-76, 1964 Epstein FH, Pollack AA, Ostrander LD Jr: An electrocardiographic survey in Peru. Amer J Med Sci 247:687-693, 1964 Blackburn H, Parlin RW" Antecedents of disease. Insurance mortality statistics. Ann NY Acad Sci 134:965-1017, 1966 Kannel MB, Kagan A, Dawber TR, et ah The epidemiology of coronary heart disease. Geriatrics 17:675-690, 1962 Blackburn H, Vasquez CL, Keys A: The aging electrocardiogram. Amer J Cardiol 20:618-627, 1967 Ostrander LD Jr: Serial electrocardiographic findings in a prospective epidemiologic study. Circulation 34:1069-1080, 1966 Francis T Jr, Epstein FH" Epidemiologic research in a total natural community, Tecumseh, Michigan, in International Conference on Comparability in Epidemiologic Studies, International Epidemiological Association (Acheson RM, ed). Milbank Memorial Fund Quarterly 43 (no. 2, Part 2): 333-342, 1965 Blackburn H, Keys A, Simonson E, et ah The electrocardiogram in population studies: a classification system. Circulation 21:1160-1175, 1960 Ostrander LD Jr" Epidemiologic study of the electrocardiographic diagnosis of left ventricular hypertrophy. Circulation 33:270-282, 1966 Goldman M J: Normal variants in electrocardiograms leading to cardiac invalidism. Amer Heart J 59:71-77, 1960
The American Journal of CARDIOLOGY