Identification of persons at risk for sudden cardiac death

Sudden cardiac death and the potential role of beta-adrenoceptor-blocking drugs

Sudden cardiac death is a major health problem in the industrially developed countries. The risk of sudden cardiac death may be reduced by early detection of coronary heart disease, elimination of the risk factors, treatment of the ischaemia in patients known to have coronary heart disease and suppression of ventricular arrhythmias. Of all the therapeutic measures currently available to reduce the risk of sudden cardiac death, beta-adrenoceptor-blocking drugs (beta blockers) appear to be the most effective. In this paper their actions are reviewed and evidence for their efficacy is presented.

Sudden unexpected cardiac death among Tasmanian men

OBJECTIVE

To examine sudden unexpected cardiac death (SUCD) in Tasmanian men and to assess the contribution of these deaths to differences in rates of mortality from ischaemic heart disease (IHD) between regions within Tasmania.

DESIGN AND SETTING

Descriptive epidemiological study based in the community.

SUBJECTS

Male residents of Tasmania aged 30 to 69 years who died from IHD suddenly and unexpectedly between 1987 and 1989.

MAIN OUTCOME MEASURES

Rates and proportions of sudden cardiac death in men who had no prior overt signs of IHD, validated by necropsy and information from the attending doctors.

RESULTS

SUCD accounted for approximately 24% of deaths from IHD among men aged 30 to 69 years in Tasmania. The ratios of observed to expected numbers of deaths occurring among manual and nonmanual workers were similar whereas there was an excess of events among men aged less than 65 years who were not working. Examination of data from necropsy reports revealed that 32% of cases showed evidence of previous "silent" myocardial infarction and 63% showed severe coronary artery disease in two or more vessels, with a further 28% having severe single vessel disease. The contribution of SUCD to total mortality from IHD varied from 20% in the north-west region to 25% in the south and 26% in the north, but the limited number of events makes it uncertain whether the variation in the rate of SUCD is significantly different from that for total mortality from IHD.

CONCLUSIONS

The proportion of deaths from IHD among men in Tasmania which are sudden and unexpected and the associated necropsy findings are consistent with those described in other population based studies of sudden cardiac death. Non-participation in the workforce was a risk factor in SUCD. As yet, we cannot distinguish whether the higher mortality rates from IHD among men in northern regions of Tasmania (P < 0.01) were due to differences in SUCD or whether the same rate of SUCD obtains in all regions of the State and the differences in mortality from IHD reflect variation in non-sudden deaths and deaths in people with overt IHD.

Death from myocardial infarction: what are the benefits of early arrival at hospital and thrombolysis?

The potential benefits of early hospital care in the event of myocardial infarction were investigated in a community-based study of all suspected cases of heart attack among people aged under 70 years in the Hunter Region of New South Wales. Between August 1984 and December 1985 acute care data were collected for 1029 cardiovascular events classified as definite myocardial infarction or sudden coronary death; 516 (50%) resulted in death within 28 days from the onset of symptoms and 325 of these deaths (63%) occurred outside hospital. Of 703 people who are known to have reached hospital alive 205 (29%) did so more than four hours after the onset of symptoms. At the time of the study fewer than 1% of patients received streptokinase. To estimate the potential benefits of increased medical care an optimistic scenario was considered in which patients who arrived at hospital more than four hours after the onset of symptoms received medical attention earlier and all eligible patients received thrombolysis. Based on the results of the Second International Study of Infarct Survival (ISIS-2), if streptokinase and aspirin had been used 14% of deaths would have been averted. If, in addition, patients had arrived at hospital earlier and received optimal benefit from thrombolysis another 13% of deaths could have been avoided. These results provide a broader perspective of the potential benefits of improved medical care than can be obtained from hospital-based studies that deal only with those heart attack victims who survive long enough to reach hospital alive.

The medical device industry and the biomedical engineer: current status and future trends

The role of new and existing technology in the development of medical devices is examined. The impact of competition and economic and regulatory pressures is assessed. The identification of clinical needs is discussed. These include the needs to reduce liability, find less invasive alternatives to surgery, improve the quality of life, and prevent disease. Career opportunities are considered in some detail.