Background: The prognostic significance of papillary muscle infarction (PapMI) on hard clinical outcomes has not been investigated in patients with reperfused ST-segment-elevation myocardial infarction. Noninvasive investigation by gadolinium-enhanced cardiac MRI enables the detection of PapMI with high spatial resolution. The aim of our study was (1) to assess the incidence, determinants, and clinical characteristics of PapMI in a large multicenter cohort of patients with ST-segment-elevation myocardial infarction and (2) to assess the prognostic significance of PapMI at 1-year follow-up.
Methods and results: We enrolled 738 patients with ST-segment-elevation myocardial infarction reperfused by primary angioplasty (<12 hours after symptom onset) in this cardiac MRI study at 8 centers. Cardiac MRI was completed within 1 week after infarction using a standardized protocol. Central core laboratory-masked analyses for the presence of PapMI were performed. The primary clinical end point of the study was the occurrence of major adverse cardiac events. PapMIs were detected in 104 patients (14%). The presence of PapMI was associated with larger infarcts (P<0.001), less myocardial salvage (P<0.001), impaired left ventricular function (P<0.001), and more pronounced reperfusion injury (P=0.02). Patients with PapMI had a significantly higher mortality (8 [7.7%] versus 12 [1.9%]) and major adverse cardiac events (21 [20.2%] versus 31 [4.9%]) rate at 12-month follow-up (P<0.001, respectively). PapMI was identified as a significant independent predictor of major adverse cardiac events (hazard ratio, 4.41 [confidence interval, 2.54-7.68]; P<0.001).
Conclusions: The presence of PapMI is associated with decreased myocardial salvage, larger infarcts, and more pronounced reperfusion injury with subsequent significantly increased major adverse cardiac event rates. Consequently, our data underscore the importance of PapMI as a marker of poor outcome in patients with ST-segment-elevation myocardial infarction.
Trial registration: ClinicalTrials.gov NCT00712101.
Keywords: magnetic resonance imaging; myocardial infarction; papillary muscles; prognosis.