(HealthDay) -- More than one-fifth of healthy middle-aged men have a low-grade systolic heart murmur that confers a nearly five-fold higher risk of future aortic valve replacement (AVR), according to a study published in the June issue of the Journal of Internal Medicine.

Johan Bodegard, M.D., Ph.D., of the Oslo University Hospital in Norway, and colleagues conducted a study involving 2,014 healthy Norwegian men, aged 40 to 59 years, who underwent heart auscultation to detect systolic heart murmur along with other standard between 1972 and 1975. Of these, 1,541 (76.5 percent) had no heart murmur, 441 (21.9 percent) had a low-grade (grade I/II) murmur, and 32 (1.6 percent) had a moderate (grade III/IV) murmur. Patients were followed for up to 35 years to determine whether the presence of a low-grade systolic murmur was associated with an increased long-term risk of AVR or (CVD) mortality.

The researchers found that men with a low-grade systolic murmur had a 4.7-fold increased age-related risk of AVR, but no increased risk of mortality due to CVD. Men with a moderate-grade systolic murmur had an 89.3-fold increased risk of AVR and a 1.5-fold, but not statistically significant, increased risk of death due to CVD.

"Low-grade systolic murmur was found in more than one-fifth of apparently healthy middle-aged men with normal ," the authors write. "Men with low-grade systolic murmur have a late development of AVR requirement, and we suggest that an auscultatory follow-up at five years could safely replace an immediate referral for echocardiography."