The effect of establishing pre-angiography thresholds on contrast utilization

Contrast induced nephropathy is linked to contrast utilization and strategies for minimizing renal injury are incorporated into many laboratories that perform coronary angiography. Contrast limits have been described, below which there is minimal incremental increase in the risk of renal injury. Whether a priori acknowledgement of these limits as part of a contrast "Time-Out" reduces contrast utilization has not been established. In this study, we investigate the effect of verbalizing pre-angiography and ½ time contrast thresholds on contrast utilization and associated clinical outcomes.

We retrospectively reviewed 5265 cases of coronary angiography (984 with contrast thresholds defined pre-procedure compared to 4281 without pre-defined contrast thresholds). There were two primary endpoints: (1) proportion of procedures that utilized an amount of contrast ≤ threshold, and (2) median difference between amount of contrast utilized and the contrast threshold. Secondary outcomes incorporated indices of renal function, and included changes in serum creatinine levels, eGFR, and CKD stage.

Compared to pre-"Time-Out" group, the post-"Time-Out" group had a higher proportion of procedures with contrast ≤ stated contrast threshold (88% vs 84%, P < 0.002), and a lower amount of total contrast volume (88 mL [IQR 60-136] versus 78 mL [IQR 53-119]). The post-"Time-Out" group also had a lower incidence of any increase in post-procedure serum creatinine (45% vs 36%; P = 0.04), and a larger median decrease of pre- to post-procedure eGFR (P = 0.04).

Acknowledgement of contrast threshold as part of a contrast "Time-Out" is associated with reduced overall contrast utilization, and likely minimizes risks of contrast-induced nephropathy.