Echocardiographic Evaluation of Left Ventricular Output in Patients with Heart Failure: A Per-Beat or Per-Minute
Donato Mele1, Gabriele Pestelli1, Davide Dal Molin1
1Cardiology Unit and LTTA Centre, University of Ferrara, Ferrara, Italy.
Insights
Stroke volume index (SVI), a per-beat measure, strongly predicts mortality in heart failure patients. Cardiac index (CI), a per-minute measure, did not show similar prognostic value, suggesting SVI is more informative for risk stratification.
Area of Science:
- Cardiology
- Clinical Medicine
- Echocardiography
Background:
- Left ventricular (LV) output is a key predictor of adverse outcomes in heart failure.
- Evaluating LV output can be done per-beat (Stroke Volume Index, SVI) or per-minute (Cardiac Index, CI).
- The comparative prognostic value of SVI versus CI in heart failure has not been established.
Purpose of the Study:
- To compare the prognostic value of per-beat (SVI) and per-minute (CI) measures of left ventricular output in patients hospitalized with heart failure.
- To determine which index, SVI or CI, is a better predictor of all-cause mortality in this patient population.
Main Methods:
- A retrospective observational study of 396 hospitalized heart failure patients who underwent echocardiography.
- Derivation of SVI and CI cutoff values (30 mL/m² and 2.3 L/min/m², respectively) in 138 patients.
- Comparison of the association of these cutoff values with all-cause mortality in 258 patients, with a median follow-up of 2.6 years.
Main Results:
- After adjusting for other predictors, SVI < 30 mL/m² was independently associated with all-cause mortality (HR 2.67; P < .001).
- Cardiac Index (CI) was not found to be independently associated with all-cause mortality.
- Risk stratification using subgroups of SVI or CI did not reveal incremental benefits.
Conclusions:
- Low LV output, defined by SVI < 30 mL/m², is a significant independent predictor of all-cause mortality in hospitalized heart failure patients.
- A per-minute assessment using CI does not appear to provide additional prognostic information beyond SVI.
- These findings suggest that SVI may be a more valuable index for prognostic evaluation in heart failure compared to CI.
Background:
Left ventricular (LV) output is a predictor of adverse outcome in patients with heart failure. It can be evaluated using a per-beat approach, measuring stroke volume index (SVI), or a per-minute approach, calculating cardiac index (CI). However, the prognostic value of these two approaches has never been compared.
Methods:
A single-center retrospective observational study was conducted in 396 hospitalized patients who underwent echocardiography for suspected heart failure. In a group of 138 consecutive patients, SVI and CI cutoff values of 30 mL/m2 and 2.3 L/min/m2, respectively, were derived to separate normal from low LV forward flow conditions. Subsequently, the association of these values with all-cause mortality was compared in a group of 258 consecutive patients. Median follow-up duration was 2.6 years (interquartile range: 2-3.2 years).
Results:
After adjustment for other outcome predictors, SVI <30 mL/m2 was independently associated with all-cause mortality with a hazard ratio of 2.67 (95% confidence interval, 1.74-4.1; P < .001), whereas CI was not. Additionally, three different subgroups of SVI (<30, 30-35, and >35 mL/m2) and CI (<1.8, 1.8-2.2, and ≥2.3 L/min/m2) were compared, and no incremental benefit of this risk stratification model was observed.
Conclusions:
Low LV output on the basis of a per-beat definition (SVI <30 mL/m2) is strongly associated with all-cause mortality in patients hospitalized with heart failure. A per-minute approach seems to add no further information to risk stratification. These findings may have implications for selecting the LV output index when evaluating prognosis in patients with heart failure.
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