BELGRADE -- Contrary to popular belief, the hot summer months are not the deadliest for cardiac patients, a leading Yugoslav heart clinic said in a report quoted by local media on Friday.

The Institute for Cardiovascular Diseases in Novi Sad said a one-year study of 560 patients indicated that heart attacks tend to occur in March and April while most deaths come in September and October.

Three out of five heart attacks occur during the daytime, but the ratio is reversed in terms of deaths -- 60 per cent of cardiac patients who expire do so at night.

The most common symptom of an attack is chest pain and occurs in more than 94 per cent of cases.

The largest group, 12.6 per cent, of those who die of a heart attack is made up of people with sedentary desk jobs, while just 2.3 per cent of the victims did jobs requiring severe physical strain, DPA quoted the study as saying.