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Silent MI common, associated with poor outcomes
As many as 45% of MIs may be silent, and silent MI is associated with elevated risk for death, according to new data from the ARIC study.
Silent MIs are more common in men but more likely to be fatal in women, and they are slightly more common in blacks than in whites, researchers reported.
“The outcome of a silent [MI] is as bad as a [MI] that is recognized while it is happening,” Elsayed Z. Soliman, MD, MSc, MS, director of the epidemiological cardiology research center at Wake Forest Baptist Medical Center, Winston-Salem, North Carolina, said in a press release. “And because patients don’t know they have had a silent [MI], they may not receive the treatment they need to prevent another one.”
Elsayed Z. Soliman
Soliman and colleagues analyzed 9,498 participants from the ARIC study without CVD at baseline (1987-1989). The outcome of interest was incident silent MI, defined as ECG evidence of MI without clinical documentation, between baseline and the fourth study visit (1996-1998). The researchers also assessed CHD and all-cause mortality from the fourth study visit to 2010. Median follow-up was 8.9 years.
During follow-up, 3.3% of participants had silent MI and 4.1% had clinically documented MI, Soliman and colleagues found.
Incidence rates were higher in men than in women for silent MI (5.08/1,000 person-years vs. 2.93/1,000 person-years; P < .0001) and clinically documented MI (7.96/1,000 person-years vs. 2.25/1,000 person-years; P < .0001), according to the researchers.
The rate of silent MI was numerically higher in blacks than in whites (4.45/1,000 person-years vs. 3.69/1,000 person-years; P = .217) but clinically documented MI was significantly higher in whites than in blacks (5.04/1,000 person-years vs. 3.24/1,000 person-years; P = .002).
Compared with those who had no MI, those who had silent MI had a threefold higher risk for CHD death (HR = 3.06; 95% CI, 1.88-4.99) and elevated risk for all-cause mortality (HR = 1.34; 95% CI, 1.09-1.65), whereas similar increased risk was observed in those with clinically documented MI (HR for CHD death = 4.74; 95% CI, 3.26-6.9; HR for all-cause mortality = 1.55; 95% CI, 1.3-1.85).
Although both sexes were at increased risk for death after silent MI or clinically documented MI, there was a trend toward mortality risk being greater in women (P for interaction for silent MI = .089; P for interaction for clinically documented MI = .051), the researchers wrote.
“The modifiable risk factors are the same for both kinds of [MI],” Soliman said in the release. “Doctors need to help patients who have had a silent [MI] quit smoking, reduce their weight, control cholesterol and [BP], and get more exercise.” – by Erik Swain
Disclosure: The researchers report no relevant financial disclosures.