Quadratic stratification of left ventricular hypertrophy and association with mitral insufficiency grading: a retrospective study using cardiac magnetic resonance.

Background: Chronic primary mitral regurgitation (MR) is caused by the defect in >1 component of the mitral valve, potentially leading to left ventricular hypertrophy (LVH). The relationship between LVH subtypes and the insufficiency grading of chronic MR remains unclear. Thus, we aimed to investigate this association and explore the impact of unhealthy habits on LVH development in patients with chronic primary MR through a cross-sectional study.

Methods: Cardiac magnetic resonance (CMR) data was retrospectively collected from 3T magnetic resonance imaging (MRI) scanners in 71 patients with chronic primary MR (range, 20-84 years, 52% men). Considered patients (with mild-to-severe MR) were enrolled between March 2015 and September 2022 from the Cardiovascular Imaging Registry of Calgary (CIROC) database. Left ventricle (LV) function was assessed using cvi42 v5.11.5. Patients were categorized into 'mild-to-severe' MR using regurgitation fraction (RF), according to the current imaging guidelines. LVH subtypes were determined using mass-to-volume (M/V) calculations. IBM SPSS was used to run all the statistical analyses. This study employed normality checks by using the Shapiro-Wilk test; one-way analysis of variance (ANOVA) and Kruskal-Wallis tests with post-hoc pairwise comparisons; Chi-squared tests, Fisher's Exact test, crosstabulation analysis, and multinomial logistic regression to examine relationships between MR severity, LVH types, and impact of lifestyle factors, significance at P<0.05.

Results: Eccentric LVH was significantly associated with increased severity of MR, while concentric remodeling (CR) was linked to decreased MR severity (χ²=13.276, P=0.03, stratified by sex χ²=7.729, P=0.005). Sex differences emerged in the overall study population. Eccentric LVH was dominantly higher than CR in both males and females (females: 57.7% vs. 42.3%, P=0.05, males: 82.8% vs. 17.2%, P=0.26). No differences were observed between age groups ('Young-Middle' = under 60 years, and 'Middle-Old' = over 60 years). Still, there were notable differences in LVH prevalence within the 'Young-Middle' age group for mild-moderate (P=0.01) and moderate-severe MR (P=0.02). Eccentric LVH was associated with higher body mass index (BMI), smoking, and frequent alcohol consumption [odds ratio (OR) 1.02, 95% confidence interval (CI): 0.56-1.26; OR 1.65, 95% CI: 1.31-6.52; OR 1.15, 95% CI: 0.26-1.34], while CR was solely associated with increased BMI (smokers OR =1.84, 95% CI: 1.25-3.91 and alcohol consumers OR =1.32, 95% CI: 0.86-2.48). Nicotine and caffeine consumption did not appear to be a risk factor for LVH (nicotine: eccentric, OR =0.99, 95% CI: 0.65-1.86; CR, OR =0.97, 95% CI: 0.69-2.39 and caffeine: eccentric, OR =0.69, 95% CI: 0.48-1.61; CR, OR =0.97, 95% CI: 0.78-4.01).

Conclusions: This study reveals sex-based associations between LVH subtypes and severity of chronic primary MR. Lifestyle factors such as cigarette smoking, alcohol consumption, and elevated BMI influence LVH risk, while nicotine and caffeine consumption exhibit minimal effects.