Inappropriate left ventricular mass: reliability and limitations of echocardiographic measurement for risk stratification and follow-up in single patients

BACKGROUND: The appropriateness of left ventricular (LV) mass to cardiac workload may be calculated by the ratio of observed LV mass to the value predicted for an individual's sex, height, and stroke work at rest. OBJECTIVE: To investigate test-retest reproducibility of observed/predicted LV mass in a single patient. DESIGN AND METHODS: We measured intraclass correlation and interval of agreement between two M-mode tracings, recorded both at the same session and 3-10 days apart in 200 participants (45 +/- 13 years, body mass index 25 +/- 4 kg/m; 99 hypertensive and 101 normotensive; 50% of each group were women) in 16 centres in Italy. Tracings were read by two observers in each centre. RESULTS: The values of observed/predicted LV mass value ranged from 40.78 to 215.50%. On the same day, the within-observer 90% interval of agreement between tracings 1 and 2 was -23 to +20%. For day-to-day test-retest within-observer variability (average three cycles), the 90% interval of agreement of the observed/predicted LV mass was -30 to +32%. The 90% interval of agreement of test-retest between-observer variability was -25 to +25%. The categorical consistency of retest in the identification of subjects with appropriate LV mass, classified in the first study (i.e. > 73% and < 128%), was 90% (k = 0.87). CONCLUSION: Measurement of the appropriateness of LV mass in single patients allows acceptable risk stratification, with a coefficient of consistency similar to that reported for LV mass. The probability of a true change (90% chance) in observed/predicted LV mass over time is maximized for a single-reader difference greater than 22%, although lesser differences might also have clinical relevance.