HEART-RATE, ISCHEMIC-HEART-DISEASE, AND SUDDEN CARDIAC DEATH IN MIDDLE-AGED BRITISH MEN

Objective-To examine the relation between resting heart rate and new m ajor ischaemic heart disease events in middle aged men with and withou t pre-existing ischaemic heart disease. Design-Prospective study of a cohort o men with eight years follow up for cardiovascular morbidity a nd mortality for all men. Setting-General practices in 24 British town s (the British Regional Heart study). Subjects-7735 men aged 40-59 yea rs drawn at random from the age-sex registers of one general practice in each town. Main outcome measures-Major ischaemic heart disease even ts such as sudden cardiac death, other deaths attributed to ischaemic heart disease, and non-fatal myocardial infarction. Results-During the follow up period of eight years, 488 men had a major ischaemic heart disease event (217 fatal and 271 non-fatal). Of these, 117 were classi fied as sudden cardiac death (death within one hour of the start of sy mptoms) The relation between heart rate and risk of all major ischaemi c heart disease events, ischaemic heart disease deaths, and sudden car diac death was examined separately in men with and without pre-existin g ischaemic heart disease. In men with no evidence of ischaemic heart disease, there was a strong positive association between resting heart rate and age adjusted rates of all major ischaemic heart disease even ts (fatal and non-fatal), ischaemic heart disease deaths, and sudden c ardiac death. This association remained significant even after adjustm ent for age, systolic blood pressure, blood cholesterol, smoking, soci al class, heavy drinking, and physical activity, with particularly hig h risk in those with heart rate greater-than-or-equal-to 90 beats/min. The increased risk seen in those with increased heart rate was largel y due to a significantly increased risk of sudden cardiac death, which was five times higher than in those with heart rate < 60 beats/min. T he effect of heart rate on sudden cardiac death was present irrespecti ve of blood pressure or smoking state. In men with pre-existing ischae mic heart disease a positive association was seen between raised heart rate and risk of all major ischaemic heart disease events, ischaemic heart disease death, and sudden cardiac death, but the effect was less noticeable than in men without pre-existing ischaemic heart disease. Conclusion-In this study of middle aged British men increased heart ra te greater-than-or-equal-to 90 beats/min) is a risk factor for fatal i schaemic heart disease events but particularly for sudden cardiac deat h. The effect is not dependent on the presence of other established co ronary risk factors and is most clearly seen in men free of pre-existi ng ischaemic heart disease at initial examination.