How to evaluate diastolic dysfunction in a patient with atrial fibrillation?

Evaluating Diastolic Dysfunction in Atrial Fibrillation

In patients with atrial fibrillation, evaluate diastolic dysfunction by averaging measurements from 3 nonconsecutive beats with cycle lengths within 10-20% of average heart rate, focusing on mitral E velocity deceleration time (DT), E/e' ratio, and tricuspid regurgitation (TR) velocity as the primary parameters. 1

Technical Requirements for Accurate Measurement

The critical first step is proper beat selection and averaging:

• Select 3 nonconsecutive cardiac cycles with RR intervals within 10-20% of the average heart rate to minimize beat-to-beat variability 1
• Match RR intervals when measuring both E and e' velocities to ensure accurate E/e' ratio calculation 1
• Patients with elevated filling pressures demonstrate less beat-to-beat variation in mitral inflow velocity, which itself provides diagnostic information 1

Primary Echocardiographic Parameters

Mitral E Velocity Deceleration Time (DT)

In patients with reduced ejection fraction and AF, DT ≤160 msec has reasonable accuracy for predicting elevated left ventricular diastolic pressures and adverse outcomes. 1

• This parameter is particularly useful because it is independent of atrial contraction 2
• DT should be the primary parameter used in patients with recent cardioversion to sinus rhythm who may have LA stunning and markedly reduced A velocity 3

E/e' Ratio

E/e' ratio ≥11 indicates elevated filling pressures in AF patients. 1

• This cutoff differs from the standard E/e' >14 used in sinus rhythm 3
• The E/e' ratio is valuable because early diastolic filling (E') is independent of atrial influence 2
• Ensure proper tissue Doppler technique with sample volume positioned in the basal myocardial segment, not in the LV cavity, atrium, or outside the heart 3

Tricuspid Regurgitation Velocity

Peak TR velocity >2.8 m/sec suggests elevated left atrial pressure. 1

• This provides a direct estimate of pulmonary artery systolic pressure when combined with right atrial pressure 3, 1
• TR velocity is particularly useful in AF because it is independent of atrial contraction 2

Additional Supporting Parameters

When the primary parameters are inconclusive or unavailable, consider:

• Peak acceleration rate of mitral E velocity ≥1,900 cm/sec² indicates elevated pressures 1
• IVRT ≤65 msec suggests elevated pressures 1
• DT of pulmonary venous diastolic velocity ≤220 msec indicates elevated pressures 1
• E/Vp ratio ≥1.4 suggests elevated pressures 1
• Pulmonary vein systolic (S) wave less than diastolic (D) wave (S/D ratio <1) supports elevated LAP 3, 2

Structural Parameters

Left atrial maximum volume index >34 mL/m² indicates chronically elevated filling pressures. 1

However, a critical caveat: LA enlargement is common in AF regardless of filling pressures, significantly limiting its specificity in this population 1, 4. The LA volume provides information about chronicity of elevated pressures rather than acute elevation 1.

Algorithmic Approach to Interpretation

Step 1: Assess Primary Parameters

Measure DT, E/e' ratio, and TR velocity using proper beat selection technique 1

Step 2: Binary Classification

The clinical target is to reach a binary conclusion: elevated LVFP or not elevated 4

Elevated filling pressures are present when:

• DT ≤160 msec (in reduced EF) 1
• E/e' ≥11 1
• TR velocity >2.8 m/sec 1
• Two or more of the above parameters meet cutoff values 3

Step 3: Integrate Clinical Context

• Consider body mass index in the evaluation algorithm 4
• Measure natriuretic peptides to complement echocardiographic findings 4
• In selected cases where diagnosis remains uncertain, cardiac catheterization with direct LAP measurement may be necessary 4, 5

Common Pitfalls and How to Avoid Them

Pitfall 1: Using standard sinus rhythm algorithms - The 2016 ASE/EACVI algorithm cannot be directly applied in AF 4. Use AF-specific cutoffs and parameters independent of atrial contraction 1, 2.

Pitfall 2: Relying on LA volume alone - LA enlargement occurs frequently in AF independent of filling pressures 1, 4. Use it only as a marker of chronicity, not acute elevation 1.

Pitfall 3: Poor beat selection - Failure to average 3 nonconsecutive beats with similar cycle lengths leads to inaccurate measurements 1. The variability itself provides diagnostic information 1.

Pitfall 4: Mismatched RR intervals - When measuring E/e' ratio, ensure the RR intervals for E and e' measurements are matched 1.

Clinical Implications by Ejection Fraction

In reduced EF with AF: Transmitral inflow pattern (particularly DT) is usually sufficient to identify elevated LAP 3. Patients with HFrEF and AF demonstrate more severe diastolic dysfunction and higher filling pressures than those with HFpEF and AF 6.

In preserved EF with AF: Multiple parameters are needed, as no single parameter is sufficient 3. The E/e' ratio (56.4 mL/m² in HFrEF vs 53.6 mL/m² in HFpEF) and LA volume index are higher in reduced EF 6.