NEDA 2023 UpdateRisk-Adjusted SVI Stratification
Hemodynamic Inputs
mL
Calculated via LVOT diameter & VTI
m²
Body Surface Area
%
Ejection Fraction
Risk Profile
Requires Stroke Volume, BSA, and LVEF to determine adjusted prognostic risk based on latest NEDA findings.
Guidelines & Evidence
Verified
Last Review: 2026
When to Use
What is Stroke Volume Index (SVI)?
Stroke Volume Index (SVI) is the volume of blood ejected from the left ventricle per heartbeat, divided by the patient's body surface area (BSA). It normalizes cardiac output for patient size, allowing comparison across individuals. SVI is a key hemodynamic parameter that reflects left ventricular forward flow and helps distinguish between "true-severe" and "pseudo-severe" aortic stenosis (AS) in patients with low-gradient AS (mean gradient <40 mmHg, peak velocity <4 m/s). Unlike ejection fraction (EF), which measures the percentage of blood ejected, SVI measures the absolute volume normalized to BSA, making it sensitive to both systolic dysfunction and restrictive physiology (small LV cavity, concentric remodeling).
Primary Clinical Indications
Low-gradient severe aortic stenosis (AS): Differentiates "low-flow" from "normal-flow" states in patients with AVA ≤1.0 cm² but mean gradient <40 mmHg. SVI ≤35 mL/m² defines low-flow (classical or paradoxical).
Prognostic stratification in AS: SVI <30 mL/m² (preserved EF) or <35 mL/m² (reduced EF) identifies patients with significantly worse 1- and 3-year mortality, independent of AVA, symptoms, and cardiac damage stage.
Guiding aortic valve replacement (AVR) timing: Low SVI with dobutamine stress echo helps identify true-severe AS (SVI increases with dobutamine) vs pseudo-severe AS (SVI unchanged or decreases).
Heart failure with preserved ejection fraction (HFpEF): SVI <35 mL/m² is common in HFpEF (40-50% of patients) and predicts worse outcomes independent of LVEF.
Cardiac resynchronization therapy (CRT) response: Low SVI (<35 mL/m²) predicts worse CRT response and higher mortality.
Monitoring after AVR or TAVI: Improvement in SVI post-intervention (increase ≥5-10 mL/m²) correlates with symptom improvement and better long-term survival.
SVI vs Other Hemodynamic Parameters
| Parameter | Definition | Normal Range | Key Limitation | Clinical Utility |
|---|---|---|---|---|
| Stroke Volume Index (SVI) | SV / BSA (mL/m²) | LV: 30-66 (men), 30-59 (women); RV: 28-75 (men), 29-66 (women) | BSA-dependent (obesity underestimates, small body habitus overestimates) | Low-flow AS, HFpEF, CRT response, prognosis |
| Stroke Volume (SV) | EDV – ESV (mL) | LV: 55-127 (men), 47-99 (women) | Not indexed to body size (tall/muscular patients have higher SV) | Cardiac output calculation, preload assessment |
| Ejection Fraction (EF) | SV / EDV × 100% | LV: 50-70% (men/women) | Normal in HFpEF, concentric remodeling, and paradoxical low-flow AS | Systolic function, heart failure classification |
| Cardiac Index (CI) | CO / BSA (L/min/m²) | 2.5-4.0 L/min/m² | Rate-dependent (heart rate), requires heart rate measurement | Shock classification, low-output states |
| Transvalvular Mean Gradient | 4V² (simplified Bernoulli) | <40 mmHg: low-gradient | Flow-dependent (underestimates in low-flow states) | AS severity classification |
Related Scores in Practice
In clinical practice, this assessment is frequently evaluated alongside other validated measures. Depending on the patient's presentation and specific diagnostic requirements, you may also need to utilize the Aortic Valve Area, Lv Ejection Fraction, Cardiac Output Calculator or the Bsa Calculator to formulate a comprehensive care plan.
Last Comprehensive Review: 2026