Hazard ratios -LSB- @ % confidence intervals ( CI ) -RSB- for HF were @ ( ref ) , @ ( @-@ @ ) , @ ( @-@ @ ) , @ ( @-@ @ ) , and @ ( @-@ @ ) , for chocolate consumption of less than @/month , @-@ / week , @-@ / week , and @ + / week , respectively , after adjusting for age , body mass index ( BMI ) , smoking , alcohol , exercise , energy intake , and history of atrial fibrillation ( P for quadratic trend = @ ) .