Objective We aimed to investigate the association of diffuse myocardial fibrosis by cardiac magnetic resonance (CMR) T₁ with complex ventricular arrhythmia (ComVA) in mitral valve prolapse (MVP).

Methods A retrospective analysis was performed on 41 consecutive patients with MVP referred for CMR between 2006 and 2011, and 31 healthy controls. Arrhythmia analysis was available in 23 patients with MVP with Holter/event monitors. Left ventricular (LV) septal T₁ times were derived from Look-Locker sequences after administration of 0.2 mmol/kg gadopentetate dimeglumine. Late gadolinium enhancement (LGE) CMR images were available for all subjects.

Results Patients with MVP had significantly shorter postcontrast T₁ times when compared with controls (334±52 vs 363±58 ms; p=0.03) despite similar LV ejection fraction (LVEF) (63±7 vs 60±6%, p=0.10). In a multivariable analysis, LV end-diastolic volume, LVEF and mitral regurgitation fraction were all correlates of T₁ times, with LVEF and LV end-diastolic volume being the strongest (p=0.005, p=0.008 and p=0.045, respectively; model adjusted R²=0.30). Patients with MVP with ComVA had significantly shorter postcontrast T₁ times when compared with patients with MVP without ComVA (324 (296, 348) vs 354 (327, 376) ms; p=0.03) and only 5/14 (36%) had evidence of papillary muscle LGE.

Conclusions MVP may be associated with diffuse LV myocardial fibrosis as suggested by reduced postcontrast T₁ times. Diffuse interstitial derangement is linked to subclinical systolic dysfunction, and may contribute to ComVA in MVP-related mitral regurgitation, even in the absence of focal fibrosis.