Background Application of percutaneous coronary intervention (PCI) in patients with acute coronary syndromes (ACS) is suboptimal in older frail individuals. This study was conducted to verify if background risk is a risk factor for underuse and diminished effectiveness of PCI in older patients.

Methods An observational cohort study was conducted using data from the Acute Myocardial Infarction in Florence 2 registry, including all ACS hospitalised in 1 year in the area of Florence, Italy. Patients aged 75+ years were selected, whose background risk was stratified with the Silver Code (SC), a validated tool predicting mortality based upon administrative data. Multivariable OR for PCI application and HR for 1-year mortality by PCI usage were calculated.

Results In 698 patients (358 women, mean age 83 years), of whom 176 had ST-segment elevation myocardial infarction (STEMI), for each point increase in SC score the odds for application of PCI decreased by 11%, whereas the hazard of 1-year mortality increased by 10%, adjusting for positive and negative predictors. PCI reduced 1-year mortality progressively more with increasing SC, with HR (95% CI) of 0.8 (0.19 to 1.21), 0.41 (0.18 to 0.45), 0.41 (0.23 to 0.74) and 0.26 (0.14 to 0.48) for SC of 0–3, 4–6, 7–10 and 11+.

Conclusions Application of PCI in older ACS patients decreased with increasing background risk. This therapeutic attitude could not be justified by decreasing effectiveness of PCI in more compromised patients: conversely, application of PCI was associated with a long-term survival advantage that increased progressively with background risk, as expressed by SC.