Impact of primary PCI volume on hospital mortality in STEMI patients: does time to presentatio matter?

The exact relationship between primary percutaneous coronary intervention (PCI) volume and mortality remains unclear. No data are available on how this relationship could be affected by time-to-presentation. The primary aim of this study was to evaluate the impact of hospital primary PCI volume on in-hospital mortality in ST-elevation myocardial infarction (STEMI) patients depending on time-to-presentation. The impact of primary PCI volume on in-hospital mortality was investigated in a prospective registry of the Lombardy region in Northern Italy, deriving data on mortality rates and number of primary PCIs from a cohort of 2,558 patients. We also explored this relationship at different times-to-presentation (a parts per thousand currency sign90 min, > 90 min-180 min, > 180 min) and risk profiles assessed with the TIMI Risk Index. A strong inverse relationship was found between primary PCI hospital volume and risk-adjusted mortality (r = -0.9; P < 0.001). High primary PCI volumes best predicted the improvement of survival when the time-to-presentation was a parts per thousand currency sign90 min (area under the curve = 0.73, P < 0.0001). At this time, the best primary PCI threshold to provide benefit was > 66 primary PCIs/year (OR = 0.21 [95% CI 0.10-0.47], P < 0.001) and those with high TIMI Risk Index achieved the greatest benefit (P < 0.001). At > 90 min-180 min, the model was less significant (P = 0.02) with a higher threshold of procedures (> 145 primary PCIs/year) required to provide benefits. The model was not predictive of survival for time-to-presentation > 180 min (P = 0.30). The reduction of mortality of STEMI patients treated at high-volume primary PCI centers is time-dependent and affected by risk profile. The greatest benefit was observed in high-risk patients presenting within 90 min from symptoms onset.