OBJECTIVES: Previous systematic reviews have found a significant inverse relationship between procedural volumes and mortality for percutaneous coronary interventions (PCI). The aim of this systematic review was to examine this volume-outcome relationship, in light of interventional cardiology advances, thereby informing the work of the National Review of Specialist Cardiac Services in Ireland.

METHODS: A systematic review was undertaken for the period 01/01/2008 to 28/05/2019 with four primary outcomes: the relationship between postoperative (inpatient/30-day) mortality and 1) total PCI (any indication) hospital volume; 2) total PCI operator volume; 3) primary PCI (emergent indications) hospital volume; 4) primary PCI operator volume. Meta-analyses of case-mix adjusted odds ratios were conducted, where appropriate. Certainty of evidence was assessed using ‘Grading of Recommendations Assessment, Development and Evaluation’ (GRADE). Protocol registration: PROSPERO CRD42019125288.

RESULTS: Of 1,154 unique records retrieved, 22 observational studies conducted in eight countries with 6,432,265 patients were included. No significant association was found between total PCI hospital volume and mortality (odds ratio [OR]: 0.84, 95% confidence interval [CI]: 0.69-1.03). A temporal trend from significant to non-significant was observed. However, the pooled effect estimate for mortality was found to be significantly in favour of high-volume operators for total PCI procedures (OR: 0.77, 95% CI: 0.63-0.94), and for high-volume hospitals for primary PCI procedures (OR: 0.77, 95% CI: 0.62-0.94). Meta-analysis was not possible for primary PCI operator volume due to limited study numbers. The pooled estimates must be interpreted with caution as there was considerable levels of heterogeneity in all meta-analyses (I² = 86%, 93% and 78% respectively). Overall, the GRADE certainty of evidence was ‘very low’.

CONCLUSIONS: A volume-outcome relationship may still exist in favour of high-volume hospitals and operators, although this relationship appears to be attenuating with time and there is very low certainty of evidence. These findings may have implications for the organisation of PCI centres.