Introduction to Occupational Cardiology


Introduction By Karen Belkic MD, PhD, and Peter Schnall MD, MPH

Cardiologists and other clinicians handling hypertension and ischemic heart disease are routinely called upon to make a judgment about cardiovascular work fitness of their patients. Unfortunately, however, the more fundamental question has rarely been posed in the clinical context. Namely, is the work environment fit, or conducive to cardiovascular health?

As recently summarized in The Workplace and Cardiovascular Disease: Occupational Medicine State of the Art Reviews (13), a large body of epidemiological as well as physiologic evidence has now accumulated implicating a number of workplace factors in the etiology of hypertension and ischemic heart disease (IHD). The evidence is particularly strong and consistent with respect to exposure to high strain work and risk of hypertension and IHD. Calculations of Population Attributable Risk (PAR%) indicate that between 20 and 30% of cases of hypertension among working men could be prevented by eliminating exposure to job strain. PAR% estimates suggest that possibly an even greater percentage of cardiovascular disease could be prevented by eliminating exposure to job strain, together with sedentary work, shift work and physical and chemical noxins. Current Trends in working life characterized e.g., by a rising level of exposure to job strain and long and irregular work hours, portend that work-related hypertension and IHD will become an increasingly important problem in the years to come.

A study by Theorell, Perski and colleagues (16) brings these issues into sharp clinical focus. Examining 79 men who had survived a first myocardial infarction before the age of 45, these authors found that return to work at a high strain job was a significant, independent predictor of IHD-related mortality after five years of follow-up. The predictive strength of return to high strain work was of comparable magnitude to degree of angiographically assessed coronary atheromatosis, and more powerful than left ventricular ejection fraction. This finding remained robust after adjustment for standard cardiac risk factors. On the basis of these data, together with the numerous cohort studies showing an excess risk of CHD morbidity and mortality among workers exposed to job strain or other untoward psychosocial work conditions, Theorell and Karasek (15) ask: “should heart attack patients return to stressful jobs?”

This same question could also be raised with respect to working people with hypertension. There is strong evidence that exposure to job strain, and other untoward occupational exposures, is associated with elevated ambulatory blood pressure (BP) and risk of hypertension (1,3, 9-11). Recent evidence (2) also indicates that work-related hypertension has been heretofore greatly underestimated because of reliance upon blood pressure measurement taken in the clinic setting, far removed from working life. The problem of “occult workplace hypertension”, namely elevated BP at work but normal clinic BP appears to be not only a highly prevalent condition, but also one that is prognostically important with respect to adverse cardiovascular outcomes (2, 8). Furthermore, observational data suggest that amelioration of exposure to psychosocial workplace stressors such as job strain is associated with a clinically important fall in blood pressure, especially among workers suffering from hypertension (11, 12).

Given the rising prevalence of working conditions that are potentially harmful to the cardiovascular system, clinicians will more and more often be faced with the quandary of whether or not to sanction their patients’ continued exposure to the work environment. Further complicating the issue is that the very jobs in which public safety could be compromised with the occurrence of sudden loss or compromise of consciousness or an acute cardiac event (4, 5) are frequently those in which exposure to potentially cardio-deleterious factors is the greatest (6).

The key role of environmental factors in the etiology of internal disease is gaining wider appreciation in the clinical community at large. The most recent edition of Harrison’s Principles of Internal Medicine contains a generic chapter entitled: Influence Of Environmental And Occupational Hazards On Disease (7), wherein, the authors state: “Exposures to hazardous materials and processes in the home, the workplace and the community can cause or exacerbate a multitude of diseases. Physicians commonly treat the sequelae of such disease in the practice of medicine; however, unless the underlying connection with hazardous exposures is identified and mitigated, treatment of the manifestations rather than the cause at best only ameliorates the condition. At worst, the neglect of hazardous exposures may lead to both failure of treatment and failure to recognize a public health problem with wide significance” (p. 18).

Other medical disciplines, notably pulmonary medicine, have already incorporated these principles into their clinical practice. Thus, e.g. there has been an extensive chapter on Environmental Lung Disease, in all of the recent editions of Harrison’s Principles of Internal Medicine.

In contrast, however, except as this relates to levels of physical exertion, the workplace has remained a relatively remote area for clinical cardiology. We believe that the time is right for a “paradigm shift” such that the workplace would become an integral consideration for cardiologic practice. Our aim with this section of the Website is to help provide a forum by which to help advance the discipline of Occupational Cardiology, as a link between primary cardiology, on the one hand, and occupational and preventive medicine, on the other.

Some areas that need to be developed in order to achieve this goal would include:

· Further refinement of our knowledge of the role of workplace stressors in the etiology of hypertension and various manifestations of CVD

· Furthering clinical acumen in taking and interpreting an occupational history, as it relates to the cardiovascular system.

· Formulating, testing and validating algorithms and guidelines for the diagnosis and management of work-related hypertension and relevant cardiovascular diseases and pre-pathologic conditions

· Promoting cooperation with other key participants such as occupational health psychologists and other occupational health specialists and epidemiologists, as well as labor and management.

· Providing legislative and policy support, in the context of which, there would be growing empowerment of the physician to formulate and implement changes at the workplace based upon clinical observations and surveillance.

We welcome an active participation from readers, especially clinicians, in this process. We would like to hear your views, experiences, queries and dilemmas. This section of the Website can also be a forum for debate, with an on-going presentation of opposing arguments.

Cited References

(1) Belkic K, Landsbergis P, Schnall P, Baker D, Theorell T, Siegrist J, Peter R, Karasek R. Psychosocial factors: Review of the empirical data among men. In: Schnall PL, Belkic K, Landsbergis PA, Baker D (eds.) Occupational Medicine: State of the Art Review. The Workplace and Cardiovascular Disease. 2000; 15 (1): 24-40.

(2) Belkic K, Schnall P, Landsbergis P, Schwartz JE, Gerber LM, Baker D, Pickering TG. Hypertension at the workplace-An occult disease? The need for worksite surveillance. Adv. Psychosom Med. In Press.

(3) Brisson C. Women, work and CVD .In: Schnall PL, Belkic K, Landsbergis PA, Baker D (eds.) Occupational Medicine: State of the Art Review. The Workplace and Cardiovascular Disease.2000; 15(1):49-57.

(4) De Gaudemaris R. Clinical issues: return to work and public safety. In: Schnall PL, Belkic K, Landsbergis PA, Baker D (eds.) Occupational Medicine: State of the Art Review. The Workplace and Cardiovascular Disease. 2000; 15 (1): 223-230.

(5) Epstein AE, Miles WM, Benditt DG, Camm AJ, Darling EJ, et al. Personal and public safety issues related to arrhythmias that may affect consciousness: Implications for regulation and physician recommendations. American Heart Association Scientific Statement, 1996.

(6) Fisher J, Belkic K. A public health approach in clinical practice. In: Schnall PL, Belkic K, Landsbergis PA, Baker D (eds.) Occupational Medicine: State of the Art Review. The Workplace and Cardiovascular Disease. 2000; 15 (1): 245-253.

(7) Hu H, Speizer FE. Influence of environmental and occupational hazards on disease. In Fauci AS, Braunwald E, Isselbacher KJ, Wilson JD, Martin JB, Kasper DL, Hauser DL, Longo D (eds.)Harrison’s Principles of Internal Medicine. 14th Edition. New York: McGraw-Hill, Inc., 1998, pp. 18-21.

(8) Liu J, Roman M, Pini R, Schwartz JE, Pickering TG, Devereux RB. Cardiac and arterial target organ damage in adults with elevated ambulatory and normal office blood pressure. Ann Intern Med 1999; 131: 564-572.

(9) Schnall PS, Pieper C, Schwartz JE, Karasek RA, Schlussel Y, Devereux RB, Ganau A, Alderman M, Warren K, Pickering T. The relationship between “job strain”, workplace diastolic blood pressure, and left ventricular mass index. Results of a case-control study. JAMA. 1990; 263: 1929-1935.

(10) Schnall PL, Schwartz JE, Landsbergis PA, Warren K, Pickering TG. Relation between job strain, alcohol and ambulatory blood pressure. Hypertension 1992; 19: 488-494.

(11) Schnall PL, Landsbergis PA, Schwartz J, Warren K, Pickering TG. A longitudinal study of job strain and ambulatory blood pressure: results of a three year follow-up. Psychosom Med 1998; 60: 697-706.

(12) Schnall PL. Hypertension: could lowering job strain be a therapeutic modality. In: Schnall PL, Belkic K, Landsbergis PA, Baker D. (eds.) The Workplace and Cardiovascular Disease. Occupational Medicine: State of the Art Reviews. 2000; 15: 233-238.

(13) Schnall PL, Belkic K, Landsbergis PA, Baker D. (eds.) The Workplace and Cardiovascular Disease. Occupational Medicine: State of the Art Reviews. 2000; 15.

(14) Shimomitsu T, Odagiri Y. Working life in Japan In: Schnall PL, Belkic K, Landsbergis PA, Baker D (eds.) Occupational Medicine: State of the Art Review. The Workplace and Cardiovascular Disease. 2000; 15: 280-281.

(15) Theorell T, Karasek R. Should heart attack patients return to stressful jobs? Stress Med 1995; 11: 219-220.

(16) Theorell T, Perski A, Orth-Gomér K, Hamsten A, de Faire U The effects of the strain of returning to work on the risk of death after a first myocardial infarction before age of 45. Int J Cardiol 1991; 30: 61-67.

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