Subjective memory symptoms in surgical and nonsurgical coronary artery patients: 6-year follow-up.

BACKGROUND: Self-reported cognitive and memory complaints after coronary artery bypass graft (CABG) operations are common. Several studies have attempted to quantify the incidence of such complaints and to examine the relationship between subjective and objective cognitive functioning, but the etiology and longitudinal course of these self-reports remain unclear.
METHODS: Measures of subjective memory complaints were compared in two groups: 220 CABG patients and 92 nonsurgical cardiac patients at 3 months, and 1, 3, and 6 years. At 6 years, additional measures were used to quantify memory self-assessment. The frequency of subjective complaints at each time point was determined, and associations with objective cognitive performance as well as depression were examined.
RESULTS: At early (3-month or 1-year) follow-up, subjective memory complaints were reported more often by the CABG than the nonsurgical group (45.5% vs 17.0%, p < 0.0001). By 6 years, the frequency of complaints was similar (52%) in both groups. Subjective memory ratings were significantly correlated with performance on several memory tests at 6 years. This relationship was not confounded by depression.
CONCLUSIONS: Subjective memory complaints are more frequent early in follow-up in patients undergoing CABG than in controls, but are similar by 6 years. The increase in subjective complaints over time may be related to progression of underlying cerebrovascular disease. Unlike previous studies, we found that subjective memory assessments were correlated with objective performance on several memory tests. Although subjective memory complaints are more common in patients with depression, they cannot be explained by depression alone.