Left-ventricular power-to-mass ratio at peak exercise predicts mortality, heart failure, and cardiovascular events in patients with stable coronary artery disease: data from the Heart and Soul Study.
BACKGROUND
Quantitative stress echocardiography enables calculation of left-ventricular power-to-mass ratio (LVPMR) at peak exercise, a novel measure of cardiac performance per unit mass of myocardial tissue. We hypothesized that LVPMR at peak exercise provides prognostic information beyond established echocardiographic indices such as left-ventricular ejection fraction (LVEF) and left-ventricular mass index (LVMI).


METHODS
LVPMR (watts/kilogram) at peak exercise was defined as (k x heart rate x mean arterial pressure x stroke volume)/LV mass. We measured LVPMR in 918 adults with stable ambulatory coronary artery disease recruited for the Heart and Soul Study. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for all-cause mortality, cardiovascular death, nonfatal myocardial infarction, heart failure hospitalization, and combined adverse cardiovascular events. Multivariate adjustments were made for established risk factors including LVEF and LVMI. The prognostic value of LVPMR was also compared with established exercise parameters using receiver-operating characteristic curve analysis.


RESULTS
Compared with patients in the highest LVPMR quartile, those in the lowest quartile were at increased risk of all-cause mortality (adjusted HR 1.9; 95% CI 1.1-3.3), heart failure hospitalization (adjusted HR 2.9; 95% CI 1.2-6.9), and combined adverse cardiovascular events (adjusted HR 1.9; 95% CI 1.1-3.4). In comparison with the rate-pressure product and the Duke treadmill score, LVPMR did not add significant prognostic value (p > 0.1 for c-statistic comparisons).


CONCLUSIONS
In patients with stable ambulatory coronary artery disease, LVPMR at peak exercise predicts mortality, heart failure hospitalization, and adverse cardiovascular events. However, LVPMR does not add significant prognostic information beyond established exercise test parameters.
Farzaneh-Far
Ramin
R
Department of Medicine, University of California, CA 94143-0124, USA.
Na
Beeya
B
Whooley
Mary A
MA
Schiller
Nelson B
NB
D000368:Aged; D000369:Aged, 80 and over; D002140:California / Q000453:epidemiology; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000401:mortality; D025401:Echocardiography, Stress; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000401:mortality