Dark-PAP sign: a new prognostic marker in patients with preserved left ventricular ejection fraction

Purpose: We sought to evaluate the prognosis-related role of papillary muscle abnormalities in patients with ventricular arrhythmias, preserved LVEF without a definite diagnosis of cardiac disease. Methods or Background: 391 patients with >500/24h premature ventricular complexes and/or with non-sustained ventricular tachycardia (NSVT), preserved LVEF and no history of cardiac disease were enrolled. Different features of papillary muscles were considered: supernumerary muscles, papillary thickness, the attachment, late gadolinium enhancement (LGE). Dark-PAP was defined as end-systolic signal hypointensity of both papillary muscles in early post-contrast cine images. Mitral valve prolapse, mitral annular disjunction (MAD) and myocardial LGE were considered. Results or Findings: Dark-PAP sign was found in 79 (20%) of patients (more frequently in females). It was associated with a higher prevalence of mitral valve prolapse and MAD. During a median follow-up of 2534 days, 22 hard cardiac events occurred. At Kaplan- Meier curve analysis patients with Dark-PAP sign were at higher risk of events than those without (p<0.0001). Dark-PAP sign was significantly associated with hard cardiac events in all the multivariate models. Dark-PAP sign improved prognostic estimation when added to NSVT (p=0.0006), to LGE of LV walls (p=0.005) and to a model including NSVT+LGE (p=0.014). Dark-PAP sign allowed a significant net reclassification when added to NSVT (NRI 0.30, p =0.03), to LGE (NRI 0.25, p =0.04), and to NSVT + LGE (NRI 0.32, p =0.02). Conclusion: Dark-PAP sign is a novel prognostic marker in patients with ventricular arrhythmias and preserved ejection fraction. Limitations: Firstly, we performed all the CMR using 1.5T machines and with a high dose of 0.5 molar Gd-based contrast agent (0.2 mmol/Kg) and acquired cine-SSFP immediately after injection. Secondly, first pass perfusion imaging could provide further information on myocardial perfusion of lateral wall and even of papillary muscles.