Background: Cardiac catheterization (CC) is a frequently performed procedure in US with over 1,000,000 procedures performed annually. Prior studies have demonstrated an inverse relationship between annual volume and complications with centers performing greater than 400 procedures annually having fewer complications. However, there has not been any investigation into the optimal daily volume of procedures to ensure the lowest risk. The objective of this study is to determine the relationship between daily volume and complication rates and to identify an optimal volume of procedures per day.
Methods: We used data captured retrospectively from the NCDR and Lumedx© database of adult patients undergoing non-emergent CC at a high-volume (>400 procedures/year) tertiary care hospital catheterization laboratory from January 2005 - June 2013. We excluded patients undergoing CC on weekends and after business hours. In the event of multiple CC, only the first event was utilized for this analysis. Complications examined included: death, post-procedure MI, cardiogenic shock, heart failure, stroke, tamponade, major bleeding, hematoma or acute kidney injury as defined by the NCDR database. We analyzed the relationship between the volume of CC conducted per day and rates of complications.
Results: Overall, 13,819 patients were included who underwent 18,287 CCs on 2,150 days. The average age was 63 years (SD 12.5; range 18-95) and 61% (8,430/13,819) were men. A total of 396 complications occurred in 305 patients on 292 separate days with a 2.2% (396/18,287) CC complication rate. The average volume per day was 8.5 CCs. On the days with a complication, the median procedural volume was 10 CCs compared to 8 CCs on days without a complication (p<0.01). We found a low correlation between the rates of complication and CC volume (Spearman’s rho=0.12; p<0.01). There was a U-shaped relationship with a higher complication rates on days with 1-5 CC and days with > 12 CC. Overall, the lowest complication rates were observed on days with 10-12 events.
Conclusions: There is a U-shaped association between CC volume and rates of CC related complications. Unlike prior studies which identified high annual volumes were associated with lower complication rate, our study results suggests that this relationship does not hold true for daily volume. There appears to be a daily limit at which complication rates begin to rise in proportion to volume. Higher complication rates were seen on days with very low CC volume (<5 procedures) and days with very high CC volume (>12 procedures). It is important that individual high volume CC labs consider a quality control analysis of their daily CC volume to determine the optimal volume associated with the fewest complications.