Prominent involvement of basal left ventricular longitudinal strain in patients with monoclonal gammopathy of undetermined significance

Abstract

Abstract Background In cardiac amyloidosis the application of Speckle Tracking Echocardiography allows to identify a specific left ventricular (LV) longitudinal strain (LS) pattern characterized by “apical sparing”, with a prominent involvement of basal and middle segments and normal LS of apical cap. The pattern of regional LS has been never investigated in monoclonal gammopathy of undetermined significance (MGUS), a condition which can predispose to cardiac amyloidosis. Purpose To compare LV regional LS patterns and LS base-to-apex behaviour of patients affected by MGUS in comparison with healthy subjects. Methods We enrolled 40 patients affected by MGUS (M/F=20/20; age 62.6±13.8 years), asymptomatic for cardiac symptoms, and a control group of 40 healthy subjects, matched for sex and age. Nineteen (47%) MGUS patients showed prevalent free K light chain and 21 (53%) had prevalent free λ light chain. Participants underwent standard echo-Doppler exam, including Speckle Tracking of the three apical views. Global longitudinal strain (GLS), the average LS of six basal (BLS), six middle (MLS), and six apical (ALS) segments (considered in absolute values) and relative regional strain ratio RRSR [=ALS/(BLS+MLS)] were computed. Exclusion criteria were overt heart failure, LV ejection fraction <53%, coronary artery and congenital heart disease, moderate to severe valvular disease, primary cardiomyopathies, atrial fibrillation and inadequate echo imaging. Results The two groups were comparable for body mass index, blood pressure and heart rate. LV mass index, relative wall thickness, left atrial volume index and Doppler-derived LV diastolic parameters did not differ significantly between the two groups. LV ejection fraction was also similar in MGUS and healthy controls. GLS resulted significantly lower in MGUS group than in controls (20.5±3.0 vs. 22.4±2.0%, p<0.02). BLS (17.1±3.7 vs. 19.2±2.2%, p=0.004), MLS (24.9±3.8 vs. 27.1±3.6%, p<0.01) and ALS (25.1±3.8 vs. 27.1±3.5%, p<0.01) were significantly lower in MGUS than in controls. The intergroup difference of RRSR (0.60±0.05 vs. 0.58±0.04) did not achieve the statistical significance (p=0.26) and none of the MGUS patients had RRSR>1. The figure depicts a LS bull'eye of a MGUS patient showing the prominent involvement of LV basal segments. Conclusions In presence of a normal LV ejection fraction, MGUS patients show a subclinical LV longitudinal systolic dysfunction. This is testified by a reduction of GLS and of regional LS which involves mainly LV basal segments, without substantial changes of relative regional strain ratio. LV regional longitudinal dysfunction could be useful to monitor LV myocardial mechanics during follow-up of MGUS patients. LS bull's eye in a MGUS patient Funding Acknowledgement Type of funding source: None