What does a left‑ventricular end‑diastolic pressure (LVEDP) below 18 mm Hg indicate about cardiac filling pressures and clinical significance?

LVEDP Below 18 mm Hg: Clinical Significance

An LVEDP below 18 mm Hg indicates normal left ventricular filling pressures and effectively rules out left ventricular failure, as the ACC/AHA defines LVEDP >18 mm Hg as the threshold for elevated filling pressures in LV dysfunction. 1

Normal LVEDP Values and Interpretation

• Normal LVEDP is typically <12 mm Hg, with values between 12-18 mm Hg representing a borderline or intermediate range 2
• LVEDP >18 mm Hg is the established cutoff for left ventricular failure, as patients with LV failure typically have LVEDP elevated above this threshold 1
• Values between 13-18 mm Hg represent an intermediate zone where LV filling pressures may be mildly elevated but do not meet criteria for overt LV failure 3

Clinical Implications of LVEDP <18 mm Hg

When LVEDP is below 18 mm Hg, this finding argues strongly against decompensated heart failure as the cause of a patient's symptoms. 1 Specifically:

• In patients with dyspnea or suspected heart failure, LVEDP <18 mm Hg suggests an alternative diagnosis should be pursued, as elevated filling pressures are a hallmark of symptomatic LV dysfunction 1
• The absence of elevated LVEDP helps distinguish pre-capillary pulmonary hypertension (where LVEDP/PCWP ≤15 mm Hg) from post-capillary pulmonary hypertension due to left heart disease (where PCWP >15 mm Hg) 4, 5
• In acute myocardial infarction, LVEDP <18 mm Hg is associated with significantly lower mortality risk compared to LVEDP >18 mm Hg (0.3% vs 0.8% in-hospital mortality) 3

Prognostic Significance

LVEDP below 18 mm Hg carries favorable prognostic implications:

• In patients undergoing PCI, those with LVEDP <13 mm Hg had the lowest in-hospital mortality (0.3%), while those with LVEDP >18 mm Hg had more than double the mortality (0.8%) 3
• In STEMI patients undergoing primary PCI, LVEDP ≤18 mm Hg was associated with significantly lower 30-day mortality (HR 2.00 for LVEDP >18 mm Hg) and 2-year mortality (HR 1.57 for LVEDP >18 mm Hg) 6
• The highest risk patients are those with LVEDP ≥24 mm Hg, who experience markedly elevated mortality rates 3, 6

Important Clinical Caveats

Several critical pitfalls must be avoided when interpreting LVEDP <18 mm Hg:

• LVEDP may be "pseudo-normal" in patients treated with diuretics, potentially masking underlying diastolic dysfunction despite apparently normal filling pressures 2, 4
• In right ventricular infarction, LVEDP may be low or normal despite hemodynamic compromise, as the primary problem is inadequate RV output leading to reduced LV filling 1
• LVEDP does not always correlate with PCWP, particularly in conditions such as mitral regurgitation, aortic regurgitation, LV hypertrophy, or during mechanical ventilation 4
• Age-related changes in diastolic function must be considered, as normal values may shift with aging 2

Relationship to Non-Invasive Parameters

When LVEDP is <18 mm Hg, corresponding echocardiographic findings typically include:

• E/e' ratio <8 usually indicates normal LV filling pressures, correlating with LVEDP <18 mm Hg 1
• Left atrial volume index <34 mL/m² suggests normal chronic filling pressures 2
• Mitral inflow E/A ratio <1 suggests delayed LV relaxation with normal filling pressures 1

However, only weak correlation exists between LVEDP and LVEF (R² = 0.03), meaning normal ejection fraction does not exclude elevated LVEDP, and conversely, reduced LVEF does not guarantee elevated LVEDP 6

Clinical Decision-Making Algorithm

When LVEDP is measured and found to be <18 mm Hg:

1. Rule out volume depletion - particularly in acute MI where 10-15% of patients may be significantly volume depleted despite ischemic injury 1
2. Consider right ventricular pathology - RV infarction or primary RV failure can present with low LVEDP despite hemodynamic compromise 1
3. Reassess the diagnosis - if heart failure was suspected, LVEDP <18 mm Hg argues against decompensated LV failure as the primary problem 1
4. Evaluate for pre-capillary pulmonary hypertension - if pulmonary pressures are elevated but LVEDP/PCWP ≤15 mm Hg, this indicates pre-capillary rather than post-capillary PH 4, 5
5. Consider provocative testing - if clinical suspicion for diastolic dysfunction remains high despite normal resting LVEDP, exercise hemodynamics or volume challenge may unmask LV dysfunction, though these require further standardization 4