The aim of the present work was to evaluate the association between coffee consumption and the development of left ventricular systolic dysfunction (LVSD) in patients who had had an acute coronary syndrome. During 2006-2007, 144 male (65 +/- 14 years) and 50 female (71 +/- 12 years) post-acute coronary syndrome patients who developed LVSD (ejection fraction <40%) after the cardiac event and 129 male (64 +/- 12 years) and 51 female (67 +/- 10 years) post-acute coronary syndrome patients without LVSD (ejection fraction >50%) were included in the study. Participants were consequently selected. Detailed information regarding their medical records, sociodemographic and anthropometric data, and various psychological and lifestyle characteristics (physical activity, smoking habits, etc.) were recorded. In particular, nutritional habits, including coffee consumption, were evaluated using a semiquantitative food-frequency questionnaire. Multi-adjusted analysis revealed that in normotensive patients coffee consumption of 1-2 cups/day was associated with 88% (95% confidence interval, 0.02-0.84) lower likelihood of developing LVSD and consumption of >3 cups/day with 90% (95% confidence interval, 0.01-0.88) lower likelihood for LVSD, compared with no history of consumption of coffee and after adjusting for various confounders. In contrast, in hypertensive patients coffee consumption of >3 cups/day was associated with 4.5-fold higher likelihood for developing LVSD (95% confidence interval, 0.89-22.58) as compared with no history of coffee consumption. Coffee consumption has opposite effects on the likelihood of developing LVSD in post-acute coronary syndrome patients depending on their blood pressure levels.