Background: The etiology and significance of flu-like symptoms often appearing before myocardial infarction should be clarified.
Methods: In a case-control study of 323 matched controls and a random sample of 110 out of 351 cases the presence of infection symptoms during the preceding four weeks before admission were asked and blood samples taken.
Results: Enterovirus (EV), herpes simplex virus (HSV), and Chlamydia pneumoniae IgA titers were significantly higher in cases than in controls (p<0.001, 0.008 and 0.046, respectively). Flu-like symptoms appeared significantly more often in patients than in controls the most common one being fatigue (p<0.001). In controls with fatigue, EV and HSV titers showed a trend to be higher (1.50 vs 1.45 and 4.29 vs 3.73) than in controls without fatigue but only HSV titers were statistically significantly higher (3.47 vs 3.96, p = 0.02). Even CRP and amyloid A concentrations (3.49 vs 2.08, p<0.0001 and 5.70 vs 3.77 mg/l, p = 0.003, respectively) as well as C4 (0.40 vs 0.44, p = 0.02) were higher in controls with fatigue.
Conclusions: Odds ratios for a coronary event in a logistic regression model were 4.79 for fatigue and 2.72 for EV antibody levels in their fourth quartile. A linear-by-linear association test showed increasing number of single symptoms with higher EV titer quartiles (p = 0.004).