Normal Values and Reference Ranges for the Ratio of Transmitral Early Filling Velocity to Early Diastolic Strain Rate: The Copenhagen City Heart Study

Evaluating left atrial strain and left ventricular diastolic strain rate as markers for diastolic dysfunction in patients with mitral annular calcification

BACKGROUND

Mitral annular calcification (MAC) poses many challenges to the evaluation of diastolic function using standard echocardiography. Left atrial (LA) strain and left ventricular early diastolic strain rate (DSr) measured by speckle-tracking echocardiography (STE) are emerging techniques in the noninvasive evaluation of diastolic function. We aim to evaluate the utility of LA strain and early DSr in predicting elevated left ventricular filling pressures (LVFP) in patients with MAC and compare their effectiveness to ratio of mitral inflow velocity in early and late diastole (E/A).

METHODS

We included adult patients with MAC who presented between January 1 and December 31, 2014 and received a transthoracic echocardiogram (TTE) and cardiac catheterization with measurement of LVFP within a 24-h period. We used Spearman's rank correlation coefficient to assess associations of LA reservoir strain and average early DSr with LVFP. Receiver operating characteristic (ROC) curves were computed to assess the effectiveness of LA strain and DSr in discriminating elevated LVFP as a dichotomized variable and to compare their effectiveness with E/A ratio categorized according to grade of diastolic dysfunction.

RESULTS

Fifty-five patients were included. LA reservoir strain demonstrated poor correlation with LVFP (Spearman's rho = 0.03, p = 0.81) and poor discriminatory ability for detecting elevated LVFP (AUC = 0.54, 95% CI 0.38-0.69). Categorical E/A ratio alone also demonstrated poor discriminatory ability (AUC = 0.53, 95% CI 0.39-0.67), and addition of LA reservoir strain did not significantly improve effectiveness (AUC = 0.58, 95% CI 0.42-0.74, p = 0.56). Average early DSr also demonstrated poor correlation with LVFP (Spearman's rho = -0.19, p = 0.16) and poor discriminatory ability for detecting elevated LVFP (AUC = 0.59, 95% CI 0.44-0.75). Addition of average early DSr to categorical E/A ratio failed to improve effectiveness (AUC = 0.62, 95% CI 0.46-0.77 vs. AUC = 0.54, 95% CI 0.39-0.69, p = 0.38).

CONCLUSIONS

In our sample, LA reservoir strain and DSr do not accurately predict diastolic filling pressure. Further research is required before LA strain and early DSr can be routinely used in clinical practice to assess filling pressure in patients with MAC.

Evaluation of Intraoperative Left-Ventricular Diastolic Function by Myocardial Strain in On-Pump Coronary Artery Bypass Surgery

OBJECTIVES

Left ventricular (LV) diastolic function strongly predicts outcomes after cardiac surgery, but there is no consensus about appropriate intraoperative assessment. Recently, intraoperative diastolic strain-based measurements assessed by transesophageal echocardiography (TEE) have shown a strong correlation with LV relaxation, compliance, and filling, but there are no reports about evaluation through the entire perioperative period. Therefore, the authors describe the intraoperative course of this novel assessment technique in patients who underwent coronary artery bypass grafting, and compare it with conventional echocardiographic measures and common grading algorithms of LV diastolic dysfunction (LVDD).

DESIGN

Prospectively obtained data.

SETTING

A single university hospital.

PARTICIPANTS

Thirty adult patients scheduled for isolated on-pump coronary artery bypass grafting surgery with preoperative preserved left and right ventricular systolic function, without significant heart valve disease and pulmonary hypertension, and an uneventful intraoperative course were included.

INTERVENTIONS

Transesophageal echocardiography was performed after induction of anesthesia (T1), after termination of cardiopulmonary bypass (T2), and after sternal closure (T3). Echocardiographic evaluation was performed in stable hemodynamic conditions, in sinus rhythm or atrial pacing, and vasopressor support with norepinephrine ≤0.1 µg/kg/min.

MEASUREMENTS AND MAIN RESULTS

Strain-based measurements of peak longitudinal strain rate during isovolumetric relaxation (SR-IVR) and during early (SR-E) and late (SR-A) LV filling were assessed using EchoPAC v204 software (GE Vingmed Ultrasound AS, Norway). Evaluation of conventional echocardiographic parameters included transmitral Doppler measures of early (E) and late (A) LV filling, as well as lateral-tissue Doppler velocity assessed during early (e´) and late (a´) LV filling, tricuspid regurgitation, and left atrial dilatation. Evaluation and grading of LV diastolic function by myocardial strain was feasible in all included patients at all time points of assessment. Using conventional grading algorithms, however, a substantial number of patients could not be sufficiently graded, falling into an indeterminate zone and not reliably estimating LVDD (T1, 40%; T2, 33%; T3, 36%). There was significant impairment of LV diastolic function after bypass, as measured by SR-IVR (T1 v T2, 0.28 s-1 [IQR 0.23; 0.31) v 0.18 s-1 [IQR 0.14; 0.22]; p < 0.001), SR-E (T1 v T2, 0.95 ± 0.34 s-1v 1.28 ± 0.36 s-1; p < 0.001), and E/SR-IVR (T1 v T2, 2.3 ± 1.0 m v 4.5 ± 2.1 m; p < 0.001]. Conventional echocardiographic measures remained unchanged during the same period (E/A T1 v T2, 1.27 [IQR 0.94; 1.59] v 1.21 [IQR 1.03; 1.47] [p = 1] and E/e´ T1 v T2, 7.0 [IQR 5.3; 9.6] v 6.35 [IQR 5.7; 9.9] [p = 0.9]). There were no significant changes in the values of SR-IVR, SR-E, SR-A, E/SR-IVR, E/A, and E/e´ before and after sternal closure (T2 v T3).

CONCLUSION

Intraoperative assessment of strain-based measurements of LV diastolic function and strain-based LVDD grading was feasible in this group of selected patients, whereas conventional parameters failed to describe LVDD sufficiently in a substantial number of patients. Diastolic strain-based measurements showed impairment of LV relaxation and compliance after bypass, which was not detected by conventional echocardiographic parameters. Therefore, diastolic myocardial strain analysis might be more sensitive in detecting myocardial diastolic dysfunction by TEE in the perioperative setting, with its dynamic changes of loading conditions, and might provide valuable and additional information on the perioperative changes of LV diastolic function.

Ratio of early transmitral inflow velocity to early diastolic strain rate predicts atrial fibrillation following acute myocardial infarction

The ratio of early transmitral filling velocity to early diastolic strain rate (E/SRe) has been proposed as a new non-invasive measurement of left ventricular filling pressure. We aimed to investigate the ability of E/SRe to predict atrial fibrillation (AF) after ST-elevation myocardial infarction (STEMI). This was a prospective cohort study of patients (n = 369) with STEMI. Patients underwent an echocardiographic examination a median of two days after pPCI. By echocardiography, transmitral early filling velocity (E) was measured by pulsed-wave Doppler, and early diastolic strain rate (SRe) was measured by speckle tracking of the left ventricle. E was indexed to SRe and the early myocardial relaxation velocity (e') to obtain the E/SRe and E/e', respectively. The endpoint was new-onset AF. During follow-up (median 5.6 years, IQR: 5.0-6.1 years), 23 (6%) of the 369 patients developed AF. In unadjusted analyses, both E/SRe and E/e' were significantly associated with AF [E/SRe: HR = 1.06; (1.03-1.10); p < 0.001, per 10 increase] and [E/e': HR = 1.11 (1.05-1.17); p < 0.001, per 1 increase] and had equal Harrell's C-statistic of 0.71. However, only E/SRe remained an independent predictor after multivariable adjustments for clinical and echocardiographic parameters [E/SRe: HR = 1.06 (1.00-1.11); p = 0.044, per 10 increase]. E/SRe was further significantly associated with AF in patients with E/e' < 14 HR = 1.09 (1.01-1.17); p = 0.030, per 10 increase), also after multivariable adjustments. E/SRe is an independent predictor of AF in STEMI patients, even in subjects with seemingly normal filling pressure.