LV Mass as a Predictor of CVD Events in Older Adults With and Without Metabolic Syndrome and Diabetes

Abstract

Objectives: The purpose of this study was to examine the prognostic significance of left ventricular (LV) mass for cardiovascular disease (CVD) events in older adults with and without metabolic syndrome (MetS) and diabetes mellitus (DM).

Background: MetS and DM are associated with increased CVD risk, but it is unclear in these groups whether subclinical CVD as shown by increased LV mass improves risk prediction compared to standard risk factors in older individuals.

Methods: We studied 3,724 adults (mean 72.4 ± 5.4 years of age, 61.0% female, 4.4% African-American) from the Cardiovascular Health Study who had MetS but not DM or had DM alone or had neither condition. Cox regression was used to examine the association of LV mass, (alone and indexed by height and body surface area [BSA]) as determined by echocardiography, with CVD events, including coronary heart disease (CHD), stroke, heart failure (HF), and CVD death, as well as total mortality. We also assessed the added prediction, discriminative value, and net reclassification improvement (NRI) for clinical utility of LV mass compared to standard risk factors.

Results: Over a mean follow-up of 14.2 ± 6.3 years, 2,180 subjects experienced CVD events, including 986 CVD deaths. After adjustment for age, sex and standard risk factors, LV mass was positively associated with CVD events in those with MetS (hazard ratio [HR]: 1.4, p < 0.001) and without MetS (HR: 1.4, p < 0.001), but not DM (HR: 1.0, p = 0.62), with similar findings for LV mass indexed for height or BSA. Adding LV mass to standard risk factors moderately improved the prediction accuracy in the overall sample and MetS group from changes in C-statistics (p < 0.05). Categorical-free net reclassification improvement increased significantly by 17% to 19% in those with MetS. Findings were comparable for CHD, CVD mortality, and total mortality.

Conclusions: LV mass is associated with increased CVD risk and provides modest added prediction and clinical utility compared to standard risk factors in older persons with and without MetS but not with DM.

Keywords: cardiovascular disease; diabetes; echocardiography; left ventricular mass; metabolic syndrome.

Figure 1. Total Cardiovascular Disease Event Rates (per 1000 person years) by LV Mass Quartile within Disease Group

A higher unadjusted cardiovascular event rate is observed across increasing LV mass quartiles for those with neither MetS/DM, MetS without DM, and for those with DM. MetS=metabolic syndrome. DM=diabetes mellitus. LV = left ventricular mass.

Figure 2. Adjusted Hazard Ratios for Total Cardiovascular Disease Events by Quartiles of LV Mass Within Disease Group

A higher adjusted hazard for cardiovascular events is observed across increasing LV mass quartiles for those with neither MetS/DM or for those with MetS without DM, but not in those with DM. MetS=metabolic syndrome. DM=diabetes mellitus. LV = left ventricular mass. †p<0.05, ‡p<0.01 compared to first quartile.