Left ventricular chamber and wall mechanics in the presence of concentric geometry.

BACKGROUND: To test the hypothesis that in the presence of left ventricular concentric geometry the definition of 'normal' ejection fraction should be reconsidered, and normality should rather be considered to have a higher than usual lower limit
METHODS: M-mode echocardiographic endocardial shortening (eS) was studied in 148 hypertensive patients with left ventricular concentric geometry (relative wall thickness > or = 0.42), 78 with normal (54 +/- 10 years, 27 women) and 70 with depressed midwall shortening (mS) (53 +/- 10 years, 26 women), based on normal distribution of stress-corrected mS, and compared to a reference adult population of 297 age-matched normal subjects (54 +/- 8 years, 121 women) with eS > or = 28%.
RESULTS: Patients with low mS exhibited higher heart rates and body mass indices than control individuals (both P < 0.01); blood pressure, left ventricular mass, relative wall thickness and peripheral resistance were higher than in patients with normal mS, whereas cardiac index was reduced (all P< 0.01). Adjustment for body mass index and race attenuated but did not eliminate the differences between the two groups of patients (0.05 < P < 0.0001). In contrast, eS was higher than normal in patients with normal midwall shortening, whereas was 'normal' in patients with low left ventricular midwall function. More than 80% of patients in the lowest quartile of apparently normal eS exhibited clear-cut low left ventricular midwall function.
CONCLUSIONS: 'Normal' left ventricular chamber function in the presence of concentric geometry is associated with depressed midwall performance, more severe left ventricular hypertrophy, lower cardiac output and higher peripheral resistance. 'Normal' eS is the hallmark of normal myocardial function when left ventricular geometry is normal, but should be considered as a marker of systolic dysfunction when associated with concentric left ventricular geometry. Normal limits for eS should be therefore reset to upper values.