Exhaustion as precursor of cardiac death.

Excess fatigue is the most prevalent precursor of sudden cardiac death. This state may reflect prolonged tension or heart disease. In order to test the first explanation a prospective study was done among 3365 males, aged 45-59 years. This cohort was followed during an average period of 9.5 years. Exhaustion was assessed by the statement: 'At the end of the day I am completely exhausted mentally and physically'. Among those free of coronary heart disease at the beginning, 69 subjects died because of myocardial infarction. Data were analysed using Cox's regression analysis. The results showed a highly significant interaction between duration of follow-up and exhaustion upon the risk of cardiac death. The hazard ratios for exhaustion were 8.96, 6.33, 4.47 and 3.16 for the first 10, 20, 30 and 40 months of follow-up respectively. Thereafter the association between exhaustion and cardiac death is no more significant. It is argued that exhaustion before cardiac death does not reflect manifest heart disease but that an interaction between prolonged tension and subclinical levels of ischaemia may increase the risk of cardiac death.