Predictors of syncope post pacemaker implantation included : age @-@ years ( HR @ , @ % CI @ to @ , p = @ ; reference range @-@ years ) , age @ years ( HR @ , @ % CI @ to @ , p = @ ) , syncope prior to pacemaker implant ( HR @ , @ % CI @ to @ , p < @ ) , previous myocardial infarction ( HR @ , @ % CI @ to @ , p = @ ) , heart failure ( HR @ , @ % CI @ to @ , p = @ ) , and high Charlson comorbidity index ( HR @ , @ % CI @ to @ , p = @ ) .