A reduction in blood flow to the heart muscle that causes no symptoms, also referred to as “silent myocardial ischemia,” is common among late middle-aged and elderly individuals without apparent Heart disease, Danish researchers report.

Silent myocardial ischemia is quite prevalent among patients with stable or unstable coronary artery disease, the authors point out, but its prevalence and prognostic significance in apparently healthy subjects are not well established.

Dr. Ahmad Sajadieh from Copenhagen University Hospital of Bispebjerg and associates evaluated 678 healthy men and women between 55 and 75 years of age who had no history of cardiovascular disease or Stroke.

The findings are published in the European Heart Journal.

Seventy-seven participants (11.4 percent) had at least one episode of silent myocardial ischemia, the authors report, and the number of episodes ranged from 1 to 40. Silent myocardial ischemia episodes lasted from 1 to 1170 minutes (on average, 58 minutes).

During an average follow-up of 53 months, in the 77 subjects in the silent myocardial ischemia group, 16 (20.7 percent) died or had a Heart Attack and 8 (10.4 percent) had other cardiac events.

In comparison, 50 (8.3 percent) total and 18 (3.0 percent) cardiac events were recorded in the participants without silent myocardial ischemia. This represents a 3.7-fold increased risk for cardiac events and a 2.7-fold increased risk for total events in patients with silent myocardial ischemia.

Event-free survival was significantly lower for both men and women who had daily silent myocardial ischemia than for those without silent myocardial ischemia, the researchers note. There was no association between the duration of silent myocardial ischemia and rates of cardiac events.

If screening for silent myocardial ischemia in the general population is to be considered, the authors conclude, it might be important to identify groups of subjects with a higher prevalence of silent myocardial ischemia or lower probability of false positives.

SOURCE: European Heart Journal, July 2005.