An Epidemiologic Study of First Degree Atrioventricular Block in Tecumseh, Michigan

doi:10.1378/chest.59.1.40

Chest

Volume 59, Issue 1, January 1971, Pages 40-46

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PR intervals of 0.22 sec or longer were detected in the electrocardiograms of 95 of 4,678 participants past 20 years of age in the Tecumseh Community Health Study. The prevalence rates were similar in men and women and remained low through the sixth decade, but increased sharply in succeeding decades. Nineteen of the 95 persons had some other manifestation of heart disease and there was a significant association between delayed atrioventricular conduction and angina pectoris or asymptomatic T wave inversion in participants past 60 years of age. Most of the cardiac abnormalities were found among older individuals. Atrioventricular block was more constant on second examination in this group and may have been due in part to sclerosis of the left side of the cardiac skeleton, as well as specific etiologic types of heart disease. Among younger and apparently healthy participants the PR interval usually shortened on repeat examination, frequently to less than 0.22 sec. There was no excess incidence of cardiovascular disease or mortality among the persons with long PR intervals during a mean period of observation of four years. Delay in atrioventricular conduction by itself appears to be a benign condition with no unfavorable prognostic significance. It is probably a transient finding among many members of the population.

Section snippets

METHODS

Tecumseh, Michigan is the site of a prospective epidemiologic study of chronic disease, particularly cardiovascular disease, in a total natural community. Details of these investigations have been published previously.15, 16, 17, 18

In 1959 and 1960 8,641 persons, 88 percent of the entire population of the community, participated in the first series of examinations. All participants gave detailed medical histories and had thorough physical examinations which were performed by experienced members

Prevalence of atrioventricular block (Table 1)

First degree atrioventricular block was not detected among participants less than 20 years of age. Prevalence rates were low among both men and women during the third through sixth decades, but rose progressively in the succeeding decades.

. Prevalence of PR Intervals of 0.22 Second or Longer in Tecumseh Study Population, 1959–1960

Empty Cell	Empty Cell	Empty Cell	Empty Cell	Empty Cell	Age Groups	Empty Cell	Empty Cell	Empty Cell	Empty Cell
Empty Cell	Empty Cell	20–29	30–39	40–49	50–59	60–69	70–79	80 +	Total
	Number examined	453	679	467	331	178	101	26	2235
Men	Number with long PR interval	5	10	9	1	9	9	6	49
	Rate per 1000	11.0	14.7	19.3	3.0	50.6	89.1	230.8

DISCUSSION

First degree atrioventricular heart block was not observed in the electrocardiograms of any participants less than 20 years of age during the first series of examinations in Tecumseh, Michigan. The prevalence of prolonged PR intervals was only 13 per 1,000 among the 4,015 persons from 20 through 59 years of age with no appreciable difference between the sexes or from one decade to another. The prevalence increased sharply in the succeeding decades, so that 43 of the 95 participants with delayed

ACKNOWLEDGMENT

The authors are grateful to Dr. Frederick H. Epstein, Director of the Tecumseh Community Health Study, for his helpful advice and suggestions, to Mr. John Napier, Associate Director for Field Operations, for his Help in assembling the data and to the entire staff for their efforts in collecting the comprehensive information about the study population.

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Cited by (27)

PR prolongation as a predictor of atrial fibrillation onset: A state-of-the-art review
2024, Current Problems in Cardiology
First-degree atrioventricular block (1-AVB), characterized by a PR interval exceeding 200 milliseconds, has traditionally been perceived as a benign cardiac condition. Recently, this perception has been challenged by investigations that indicate a potential association between PR prolongation and an elevated risk of atrial fibrillation (AF). To consolidate these findings, we performed a comprehensive review to assess the available evidence indicating a relationship between these two conditions. We searched MEDLINE and EMBASE databases as well as manually searched references of retrieved articles. We selected 18 cohort studies/meta-analyses involving general and special populations. Consistent findings across expansive cohort studies reveal that incremental increases in the PR interval may serve as an independent risk factor for AF. However, our analyses underscore the need for further research into the association between 1-AVB, defined by a specified PR interval cutoff, and the risk of AF.
Epidemiology and Outcomes Associated with PR Prolongation
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Prolonged PR interval and incidence of atrial fibrillation, heart failure admissions, and mortality in patients with implanted cardiac devices: A real-world survey
2023, Heart Rhythm O2
Citation Excerpt :
The PR interval measures the time from the beginning of atrial depolarization to the onset of ventricular depolarization (1). Prolonged PR interval defined as PR interval > 200 milliseconds (ms), also known as first degree atrioventricular block, is commonly seen in the general population, with higher prevalence in older individuals (2). The prevalence of prolonged PR interval across different studies ranged from 2% to 14%, with overall mean prevalence of 7% (3).
Prolongation of the PR interval has long been considered a benign condition, particularly in the setting of nonstructural heart disease.
The purpose of this study was to investigate the effect of PR interval on various well-adjudicated cardiovascular outcomes using a large real-world population data of patients with implanted dual-chamber permanent pacemakers or implantable cardioverter-defibrillators.
PR intervals were measured during remote transmissions in patients with implanted permanent pacemakers or implantable cardioverter-defibrillators. Study endpoints (time to the first occurrence of AF, heart failure hospitalization [HFH], or death) were obtained between January 2007 and June 2019 from the deidentified Optum de-identified Electronic Health Record dataset.
A total of 25,752 patients (age 69.3 ± 13.9 years; 58% male) were evaluated. The average intrinsic PR interval was 185 ± 55 ms. In the subset of 16,730 patients with available long-term device diagnostic data, a total of 2555 (15.3%) individuals developed AF during 2.59 ± 2.18 years of follow-up. The incidence of AF was significantly higher (up to 30%) in patients with a longer PR interval (ie, PR interval ≥270 ms; P < .05). Time-to-event survival analysis and multivariable analysis showed that PR interval ≥190 ms was significantly associated with higher incidence of AF, HFH, or HFH or death when compared with shorter PR intervals (P < .05 for all 3 parameters).
In a large real-world population of patients with implanted devices, PR interval prolongation was significantly associated with increased incidence of AF, HFH, or death.
Epidemiology and Outcomes Associated with PR Prolongation
2021, Cardiac Electrophysiology Clinics
Citation Excerpt :
The etiologies of PR prolongation include organic heart disease from ischemia, inflammatory and infiltrative diseases, medications, autonomic influences, and collagen vascular disorders as well as idiopathic causes in patients without a history of cardiovascular disease. Although PR prolongation has classically been considered a benign finding, many of the original studies analyzing outcomes in patients with PR prolongation are confounded by selection bias including enrollment of primarily healthy, young male subjects with low burden of comorbid medical conditions.2–6 More contemporary analyses have linked PR prolongation with adverse outcomes including progression of conduction system disease, increased risk of atrial remodeling and atrial arrhythmias,7,8 and increased risk of all-cause mortality.9
Outcomes Related to First-Degree Atrioventricular Block and Therapeutic Implications in Patients with Heart Failure
2016, JACC: Clinical Electrophysiology
Citation Excerpt :
The authors did not report the percentage of participants who developed new PR prolongation during follow-up. An epidemiological study of PR interval duration in the 4,678 men and women in Tecumseh, Michigan, showed no increase in mortality amongst the 2% of the population with PR ≥220 ms during mean follow-up of 4 years (3). Three other studies have similarly found first-degree AVB to be a benign condition in healthy adults (Table 1) (1,2,32).
The prevalence of first-degree atrioventricular block in the general population is approximately 4%, and it is associated with an increased risk of atrial fibrillation. Cardiac pacing for any indication in patients with first-degree heart block is associated with worse outcomes compared with patients with normal atrioventricular conduction. Among patients with heart failure, first-degree atrioventricular block is present in anywhere between 15% and 51%. Data from cardiac resynchronization therapy studies have shown that first-degree atrioventricular block is associated with an increased risk of mortality and heart failure hospitalization. Recent studies suggest that optimization of atrioventricular delay in patients with cardiac resynchronization therapy is an important target for therapy; however, the optimal method for atrioventricular resynchronization remains unknown. Understanding the role of first-degree atrioventricular block in the treatment of patients with heart failure will improve medical and device therapy.
Short- and long-term outcomes depending on electrical dyssynchrony markers in patients presenting with acute heart failure: Clinical implication of the first-degree atrioventricular block and QRS prolongation from the Korean Heart Failure registry
2013, American Heart Journal
Prolongations of PR interval and QRS duration on 12-lead electrocardiogram are associated with atrioventricular and interventricular/intraventricular dyssynchrony, respectively. However, their clinical significance remains unclear in real-world heart failure (HF) population. We assessed whether the presence of first-degree atrioventricular block and/or QRS prolongation (≥120 ms) is associated with worse short- and long-term outcomes in patients with acute HF.
The Korean Heart Failure is a nationwide registry of 3,200 consecutive patients presenting with acute HF at 24 centers in South Korea between June 2004 and April 2009. We selected 1,986 patients with sinus rhythm and divided them into 4 groups depending on the presence of first-degree atrioventricular block and/or QRS prolongation; ED_Neither (n = 1,347), ED_PR (n = 217), ED_QRS (n = 329), and ED_Both (n = 93) groups, respectively.
During the median follow-up of 18.2 months, overall death rate (17%, 22%, 20%, and 29%, P < .01) tended to rise with increasing number of electrical dyssynchrony markers. Patients in ED_Both group showed worst outcomes regarding the requirement of invasive managements during the index admission, in-hospital mortality, postdischarge death/rehospitalization, and cardiac device implantation. In time-dependent Cox regression analyses, presence of both PR >200 ms and QRS ≥120 ms was independently associated with in-hospital death (P < .01), postdischarge death/rehospitalization (P = .03), cardiac device implantation (P < .01), and overall death (P < .01).
A combined analysis of electrical dyssynchrony markers (PR prolongation and QRS widening) might be useful for short- and long-term risk stratifications of patients with acute HF.

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: This work was supported in part by the Cardiovascular Research Center under Program Project Grant HE-09814 from the National Heart Institute, National Institutes of Health, U.S. Public Health Service. Presented at the Conference on Cardiovascular Epidemiology, sponsored by the American Heart Association, National Heart Institute and Louisiana Heart Association, New Orleans, March 3–4, 1869.

^{^**}: Formerly Instructor in Internal Medicine, University of Michigan; currently Assistant Professor of Medicine, Marquette School of Medicine, Milwaukee.

^{^†}: Associate Professor of Internal Medicine.

^{^‡}: Research Associate in Epidemiology.

^{^§}: International Postdoctoral Research Fellow (USPHS No 3F05–01-A1-S1).

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Chest

An Epidemiologic Study of First Degree Atrioventricular Block in Tecumseh, Michigan

Section snippets

METHODS

Prevalence of atrioventricular block (Table 1)

DISCUSSION

ACKNOWLEDGMENT

Amer Heart J

Amer Heart J

Amer J Cardiol

Amer J Clin Nutr

Amer J Med

The electrocardiogram in population studies. A classification system

Circulation

Delayed conduction in dystrophica myotonia

Dis Chest

Heart block in ankylosing spondylitis

Arch Int Med

Electrocardiographic findings in 122,043 individuals

Circulation