Background We previously reported that major depression in patients in
the hospital after a myocardial infarction (MI) substantially increas
es the risk of mortality during the first 6 months. We examined the im
pact of depression over 18 months and present additional evidence conc
erning potential mechanisms linking depression and mortality. Methods
and Results Two-hundred twenty-two patients responded to a modified ve
rsion of the National Institute of Mental Health Diagnostic Interview
Schedule (DIS) for a major depressive episode at approximately 7 days
after MI. The Beck Depression Inventory (BDI), which measures depressi
ve symptomatology, was also completed by 218 of the patients. All pati
ents and/or families were contacted at 18 months to determine survival
status. Thirty-five patients met the modified DIS criteria for major
in-hospital depression after the MI. Sixty-eight had BDI scores greate
r than or equal to 10, indicative of mild to moderate symptoms of depr
ession. There were 21 deaths during the follow-up period, including 19
from cardiac causes. Seven of these deaths occurred among patients wh
o met DIS criteria for depression, and 12 occurred among patients with
elevated BDI scores. Multiple logistic regression analyses showed tha
t both the DIS (odds ratio, 3.64; 95% confidence interval [CI], 1.32 t
o 10.05; P=.012) and elevated BDI scores (odds ratio, 7.82; 95% CI, 2.
42 to 25.26; P=.0002) were significantly related to 18-month cardiac m
ortality. After we controlled for the other significant multivariate p
redictors of mortality in the data set (previous MI, Killip class, pre
mature ventricular contractions [PVCs] of greater than or equal to 10
per hour), the impact of the BDI score remained significant (adjusted
odds ratio, 6.64; 95% CI, 1.76 to 25.09; P=.0026). In addition, the in
teraction of PVCs and BDI score marginally improved the model (P=.094)
. The interaction showed that deaths were concentrated among depressed
patients with PVCs of greater than or equal to 10 per hour (odds rati
o, 29.1; 95% CI, 6.97 to 122.07; P<.00001). Conclusions Depression whi
le in the hospital after an MI is a significant predictor of 18-month
post-MI cardiac mortality. Depression also significantly improves a ri
sk-stratification model based on traditional post-MI risks, including
previous MI, Killip class, and PVCs. Furthermore, the risk associated
with depression is greatest among patients with greater than or equal
to 10 PVCs per hour, This result is compatible with the literature sug
gesting an arrhythmic mechanism as the link between psychological fact
ors and sudden cardiac death and underscores the importance of develop
ing screening and treatment programs for post-MI depression.