Subclinical myocardial fibrosis is almost ubiquitous in the hearts of older British persons: 'MyoFit46' cardiovascular sub-study of the NSHD

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Abstract Background Unprecedented numbers are now surviving to older age, but little is known about the burden or pattern of myocardial fibrosis in the asymptomatic elderly population. Previous 1.5 Tesla (T) cardiovascular magnetic resonance (CMR) studies found a prevalence of unexpected infarct-pattern late gadolinium enhancement (LGE) of 17-20% above 75 years but less is known about non-infarct pattern scar in this group. We investigated the prevalence, patterns, and clinical predictors of left ventricular (LV) scar in a large asymptomatic older age cohort. Methods CMR with a single 3T magnet was performed on participants all born in the same week in March 1946, as part of the longest running continued surveillance birth cohort: the National Survey of Health and Development. LV short-axis stack LGE imaging was performed using a free-breathing motion-corrected balanced steady-state free precession sequence with phase-sensitive inversion-recovery. Two blinded observers independently recorded the prevalence, extent, and pattern of LGE per participant. Logistic regression was used to study the association between clinicodemographic parameters and LGE. Results 460 participants were prospectively recruited of which 406 completed CMR with LGE imaging (77.8 ± 0.1 years, 44% male). 341 (84%) demonstrated LGE affecting a mean of 2.1±1.2 myocardial segments per participant (Figure 1). The commonest pattern of LGE was inferior right ventricular insertion point (RVIP), observed in 66.9%. Other patterns included (Figure 2): Linear mid-wall (19.6%) of which 38% were located in the inferior/lateral walls; subepicardial (12.1%); subendocardial infarct-pattern (8.8%); patchy/diffuse (1.6%); embolic LGE (0.6%). Sub-analysis was performed comparing those without significant unexpected fibrosis (LGE–) vs those with focal fibrosis (LGE+, excluding RVIP and those participants with a known history of prior myocardial infarction). LGE+ participants were more likely to be female (71.7% vs 49.1%, p<0.001) or diabetic (11.3% vs 5.1%, p=0.05), had a higher body surface area (BSA, 1.9 vs 1.8 m2, p<0.001), weight (80.1 vs 72.8 kg, p<0.001), LV indexed end systolic volume (24.2 vs 20.4 ml/m2, p=0.001) and LV indexed mass (59.2 vs 55.4 g/m2, p<0.001), and a lower LV ejection fraction (67.9 vs 71.8%, p<0.001) In multivariable logistic regression: BSA, LV indexed mass, LV ejection fraction and diabetic status were independently associated with LGE+ status (odds ratios [95% confidence intervals]: 9.4 [0.7–3.8]; 1.0 [0.01–0.05]; 0.9 [-0.08--0.02]; and 2.5 [0.03–1.7] respectively, p<0.05). Conclusion Advanced PSIR MOCO LGE imaging at 3T reveals that the majority (84%) of asymptomatic British persons above the age of 75 harbour unexpected ‘subclinical’ focal fibrosis, with a substantial proportion of these scars consistent with probable historical myocarditis events. Further work will now explore the life-course determinants of this scar burden in the older age human heart.