Impact of stroke volume assessment by three-dimensional transesophageal echocardiography on the classification of low-gradient aortic stenosis

BACKGROUND

Accurate assessment of flow status is crucial in low-gradient aortic stenosis (AS). However, the clinical implication of three-dimensional transesophageal echocardiography (3DTEE) on flow status evaluation remains unclear. This study aimed to investigate the assessment of flow status using 3D TEE in low-gradient AS patients.

METHODS

We retrospectively reviewed patients diagnosed with low-gradient AS and preserved ejection fraction at our institution between 2019 and 2022. Patients were categorized into low-flow/low-gradient (LF-LG) AS or normal-flow/low-gradient (NF-LG) AS based on two-dimensional transthoracic echocardiography (2DTTE). We compared the left ventricular outflow tract (LVOT) geometry between the two groups and reclassified them using stroke volume index (SVi) obtained by 3DTEE.

RESULTS

Among 173 patients (105 with LF-LG AS and 68 with NF-LG AS), 54 propensity-matched pairs of patients were analyzed. 3DTEE-derived ellipticity index of LVOT was significantly higher in LF-LG AS patients compared to NF-LG AS patients (p = 0.012). We assessed the discordance in flow status classification between SVi2DTTE and SVi3DTEE in both groups using a cutoff value of 35 ml/m2. The LF-LG AS group exhibited a significantly higher discordance rate compared to the NF-LG AS group, with rates of 50% and 2%, respectively. The optimal cutoff values of SVi3DTEE for identifying low flow status, based on 2DTTE-derived cutoff values, were determined to be 43 ml/m2.

CONCLUSIONS

LVOT ellipticity in low-gradient AS patients varies depending on flow status, and this difference contributes to discrepancies between SVi3DTEE and SVi2DTTE, particularly in LF-LG AS patients. Utilizing SVi3DTEE is valuable for accurately assessing flow status.

Prognostic value of flow-status in severe aortic stenosis patients undergoing percutaneous intervention

PURPOSE

Low-flow status is a mortality predictor in severe aortic stenosis (SAS) patients, including after transcatheter aortic valve implantation (TAVI) treatment. However, the best parameter to assess flow is unknown. Recent studies suggest that transaortic flow rate (FR) is superior to currently used stroke volume index (SVi) in defining low-flow states. Therefore, we aimed to evaluate the prognostic value of FR and SVi in patients undergoing TAVI.

METHODS

A single-centre retrospective analysis of all consecutive patients treated with TAVI for SAS between 2011 and 2019 was conducted. Low-FR was defined as < 200 mL/s and low-SVi as < 35 mL/m2. Primary endpoint was all-cause five-year mortality, analyzed using Kaplan-Meier curves and Cox regression models. Secondary endpoint was variation of NYHA functional class six months after procedure. Patients were further stratified according to ejection fraction (EF < 50%).

RESULTS

Of 489 cases, 59.5% were low-FR, and 43.1% low-SVi. Low-flow patients had superior surgical risk, worse renal function, and had a higher prevalence of coronary artery disease. Low-FR was associated with mortality (hazard ratio 1.36, p = 0.041), but not after adjustment to EuroSCORE II. Normal-SVi was not associated with survival, despite a significative p-trend for its continuous value. No associations were found for flow-status and NYHA recovery. When stratifying according to preserved and reduced EF, both FR and SVi did not predict all-cause mortality.

CONCLUSION

In patients with SAS undergoing TAVI, a low-FR state was associated with higher mortality, as well as SVi, but not at a 35 mL/m2 cut off.

Orthostatic chronotropic incompetence in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Background

Orthostatic intolerance (OI) is a core diagnostic criterion in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The majority of ME/CFS patients have no evidence of hypotension or postural orthostatic tachycardia syndrome (POTS) during head-up tilt, but do show a significantly larger reduction in stroke volume index (SVI) when upright compared to controls. Theoretically a reduction in SVI should be accompanied by a compensatory increase in heart rate (HR). When there is an incomplete compensatory increase in HR, this is considered chronotropic incompetence. This study explored the relationship between HR and SVI to determine whether chronotropic incompetence was present during tilt testing in ME/CFS patients.

Methods

From a database of individuals who had undergone tilt testing with Doppler measurements for SVI both supine and end-tilt, we selected ME/CFS patients and healthy controls (HC) who had no evidence of POTS or hypotension during the test. To determine the relation between the HR increase and SVI decrease during the tilt test in patients, we calculated the 95% prediction intervals of this relation in HC. Chronotropic incompetence in patients was defined as a HR increase below the lower limit of the 95th % prediction interval of the HR increase in HC.

Results

We compared 362 ME/CFS patients with 52 HC. At end-tilt, tilt lasting for 15 (4) min, ME/CFS patients had a significantly lower SVI (22 (4) vs. 27 (4) ml/m²; p < 0.0001) and a higher HR (87 (11) vs. 78 (15) bpm; p < 0.0001) compared to HC. There was a similar relationship between HR and SVI between ME/CFS patients and HC in the supine position. During tilt ME/CFS patients had a lower HR for a given SVI; 37% had an inadequate HR increase. Chronotropic incompetence was more common in more severely affected ME/CFS patients.

Conclusion

These novel findings represent the first description of orthostatic chronotropic incompetence during tilt testing in ME/CFS patients.

Low Transvalvular Flow Rate in Patients Undergoing Transcatheter Aortic Valve Implantation (TAVI) Is a Predictor of Mortality: The TFR-TAVI Study

BACKGROUND

Transvalvular flow rate (TFR) represents a better reflection of transvalvular flow than the stroke volume index (SVi), and has recently emerged as a useful prognostic tool in patients undergoing surgical aortic valve replacement. There is a paucity of data investigating the role of TFR and its relationship with other clinical or echocardiographic factors in patients undergoing transcatheter aortic valve implantation (TAVI).

METHOD

This was a retrospective single-centre study of 629 consecutive patients who underwent TAVI between March 2009 and September 2020. Pre-TAVI low TFR was defined as <200 c/s. The primary study end point was all-cause mortality.

RESULTS

Low TFR was observed in 41.8% (263/629) of included patients and was associated with increasing age, low body surface area, hypertension, diabetes, atrial fibrillation, left ventricular (LV) dysfunction, and significant mitral regurgitation. LV function status and severity of aortic valve disease were independent predictors of low TFR. Low TFR was significantly associated with long-term all-cause mortality even after adjustment for other risk factors (adjusted hazard ratio [aHR] 1.44; 95% confidence interval [CI] 1.02-2.03; p=0.038). When data were stratified according to SVi, low TFR was an independent predictor of long-term all-cause mortality in patients with normal SVi (aHR 1.98; 95% CI 1.06-3.69; p=0.032) but not in patients with low SVi (HR 1.23; 95% CI 0.71-2.11; p=0.46; p=0.016 for interaction).

CONCLUSIONS

Low TFR is common in patients undergoing TAVI and is an independent predictor of all-cause mortality, particularly in patients with normal SVi.

Outcome of Patients With Both Moderate Aortic Stenosis and Moderate Mitral Stenosis

Aims

This study aimed to investigate the symptoms and prognosis of patients with both moderate aortic stenosis (AS) and mitral stenosis (MS).

Methods and Results

We studied 82 patients with moderate AS and MS diagnosed via transthoracic echocardiography. The patients had a mean age of 79 ± 13 years and 95% of patients had degenerative MS. Out of 82 patients, 34 (41%) had heart failure (HF) symptoms (New York Heart Association class ≥ Ⅱ) or a history of HF admission. Left ventricular ejection fraction, stroke volume index, atrial fibrillation, and right ventricular systolic pressure were independent determinants of HF symptoms. The median follow-up duration was 3.2 (interquartile range, 1.0-4.9) years and clinical events occurred in 48 (59%) patients, including death in 11 (13%) patients, aortic or mitral valve interventions in 22 (27%) patients, and HF hospitalization in 15 (18%) patients. The 5-year survival free of the combined endpoint of aortic or mitral valve interventions, HF hospitalization, or death was 19%. A multivariate predictor of clinical events was HF symptoms (hazard ratio [HR], 2.32; 95% confidence interval [CI], 1.30-4.14; p = 0.0045). Kaplan-Meier survival at 5 years was 61% without intervention and HF symptoms were not associated with mortality.

Conclusions

Among patients with both moderate AS and MS, left ventricular ejection fraction, stroke volume index, atrial fibrillation, and right ventricular systolic pressure were strong determinants of HF symptoms. HF symptoms were independently predictive of clinical events.

The prognostic significance of stroke volume index in low gradient severe aortic stenosis: from the national echo database of Australia

Approximately 50% of patients with severe aortic stenosis (AS) in clinical practice present with 'low-gradient' haemodynamics. Stroke Volume Index (SVI) is a measure of left ventricular output, with 'normal-flow' considered as  > 35 ml/m2. The association between SVI and prognosis in severe low-gradient AS (LGAS) in currently not well-understood. We analysed the National Echo Database of Australia (NEDA) and identified 109,990 patients with sufficiently comprehensive echocardiographic data, linked to survival information. We identified 1,699 with severe LGAS and preserved ejection fraction (EF) (≥ 50%) and 774 with severe LGAS and reduced EF. One- and three-year survival in each subgroup were assessed (follow-up of 74 ± 43 months), according to SVI thresholds. In patients with preserved EF the mortality "threshold" was at SVI < 30 ml/m2; 1- and 3-year survival was worse for those with SVI < 30 ml/m2 relative to those with SVI > 35 ml/m2 (HR 1.80, 95% CI 1.32-2.47 and HR 1.38, 95% CI 1.12-1.70), while survival was similar between those with SVI 30-35 ml/m2 and SVI > 35 ml/m2. In patients with reduced EF the mortality "threshold" was 35 ml/m2; 1- and 3-year survival was worse for both those with SVI < 30 ml/m2 and 30-35 ml/m2 relative to those with SVI > 35 ml/m2 (HR 1.98, 95% CI 1.27-3.09 and HR 1.41, 95% CI 1.05-1.93 for SVI < 30 ml/m2 and HR 2.02, 95% CI 1.23-3.31 and HR 1.56, 95% CI 1.10-2.21 for SVI 30-35 ml/m2). The SVI prognostic threshold for medium-term mortality in severe LGAS patients is different for those with preserved LVEF (< 30 ml/m2) compared to those with reduced LVEF (< 35 ml/m2).

Proposal criteria of paradoxical low-flow low-gradient aortic stenosis for predicting prognosis in patients undergoing transcatheter aortic valve implantation

BACKGROUND

Paradoxical low-flow, low-gradient (PLF-LG) aortic stenosis (AS) is associated with poor prognosis in patients undergoing transcatheter aortic valve implantation (TAVI). This study aimed to verify the conventional criteria of PLF-LG AS (left ventricular ejection fraction [LVEF] > 50%, mean aortic valve pressure gradient [AVPG] < 40 mm Hg and stroke volume index [SVI] < 35 ml/m² by measuring Doppler method) compatible for predicting prognosis in patients undergoing TAVI.

MATERIALS AND METHODS

A total of 128 consecutive patients who underwent TAVI for AS with LVEF > 50% were enrolled. The primary endpoint was the hospital readmission due to heart failure (HRHF) and the secondary endpoint was all-cause mortality after hospital discharge. The patients were classified by both the conventional criteria of PLF-LG AS and the proposal criteria of PLF-LG AS if mean aortic valve pressure gradient (AVPG) < 40 mmHg and SVI by measuring Simpson's method < cut off value based on the ROC curve for predicting HRHF.

RESULTS

According to the conventional criteria, only 6 patients were diagnosed with PLF-LG AS. However, according to the proposal criteria, 16 patients were diagnosed with PLF-LG AS. Fourteen patients developed HRHF during the follow-up period after TAVI. Based on the ROC curves, SVI by measuring Simpson's method (cut off value = 25 ml/m²) had higher sensitivity and specificity for predicting HRHF (AUC = 0.74, p = 0.0013) than SVI by measuring Doppler method (AUC = 0.63, p = 0.045). The multivariate analysis revealed that PLF-LG AS defined by the proposal criteria (HR: 5.25; 95% CI: 1.60-17.16; p = 0.0073) but not by the conventional criteria was independently associated with HRHF. PLF-LG AS defined by the conventional criteria and the proposal criteria were not associated with all-cause mortality in the univariate analysis.

CONCLUSIONS

Our results demonstrated that new criteria of PLF-LG AS defined as SVI < 25 ml/m² measured by Simpson's method could predict HRHF in patients with severe AS who underwent TAVI.

Echocardiographic Killip Classification

BACKGROUND

Although routine echocardiographic parameters such as ejection fraction are used to risk-stratify for death in patients referred for echocardiography, they have limited predictive value. The authors speculated that noninvasive hemodynamic echocardiographic data, assessing left ventricular filling pressure and output, stratified on the basis of the clinical Killip score, might have additive prognostic value on top of routine echocardiographic parameters. The authors created an echocardiographic correlate of this classification, using diastolic grade and stroke volume index (SVI) as indicators of pulmonary congestion and systemic perfusion, respectively, and evaluated the prognostic value of this correlate.

METHODS

A retrospective study of consecutive patients (hospitalized or not) referred for echocardiography for a range of cardiac diagnoses in a tertiary medical center. A total of 556 patients in sinus rhythm who were evaluated by two sonographers, and reviewed by a single cardiologist, were included. Normal filling pressure and normal SVI (>35 mL/m²) defined echocardiographic Killip (eKillip) class 1. Patients with pseudonormal or restrictive diastolic patterns and normal SVI were ascribed to eKillip class 2 or 3, respectively. A pseudonormal or restrictive diastolic pattern and a subnormal SVI defined eKillip class 4.

RESULTS

eKillip class 1 was present in 382 patients (68%); 115 (20%), 26 (5%), and 42 (7%) patients were in eKillip classes 2 to 4, respectively. Median follow-up time was 1,056 days (interquartile range, 729-1,390 days). A total of 105 deaths occurred. Univariate Cox regression analysis showed that eKillip class was associated with all-cause mortality; hazard ratios (HR) -2.73 (95% CI, 1.67-4.48), 3.19 (95% CI, 1.42-7.17), and 4.79 (95% CI, 2.58-8.89) for each eKillip class above 1 (P < .001). In a multivariate analysis adjusted for the Charlson comorbidity index, eKillip class remained independently associated with all-cause mortality (P = .04).

CONCLUSIONS

eKillip class was associated with all-cause mortality among all patients undergoing echocardiography at a tertiary hospital.

The Utility of Flow Rate Compared with Left Ventricular Stroke Volume Index in the Hemodynamic Classification of Severe Aortic Stenosis with Preserved Ejection Fraction

OBJECTIVES

To substitute the stroke volume index (SVi) with flow rate (FR) in the hemodynamic classification of severe aortic stenosis (AS) with preserved ejection fraction (EF), in order to evaluate its prognostic value.

METHODS

A total of 529 patients (78.8 ± 9.8 years old, 44.1% males) with isolated severe AS (aortic valve area, AVA < 1 cm2), EF ≥50%, in sinus rhythm, who underwent transthoracic echocardiography, were stratified by FR (≥/< 200 mL/s) and mean pressure gradient (MG) (≥/< 40 mm Hg): FRnormal/MGhigh, FRlow/MGhigh, FRnormal/MGlow, and FRlow/MGlow.

RESULTS

Aortic valve replacement was more frequently performed in the FRnormal/MGhigh than in the FRlow/MGlow group (69.3 vs. 47%, respectively, p < 0.0001), yielding a similar survival benefit across all four groups. Over a median follow-up of 51 ± 29 months, there were 249 deaths. In highly adjusted models, the FRlow/MGlow group had a higher all-cause mortality (HR = 1.7, 95% CI: 1.1-2.6, p = 0.02) than patients with FRnormal/MGhigh. FR had a stronger association with AVA than SVi (r = 0.51 vs. 0.41, respectively, p = 0.0002), and a similar predictive value for death (AUC = 0.57 and 0.58, respectively, p = 0.88).

CONCLUSIONS

The FRlow/MGlow subset of AS is associated with the worst prognosis, and FR is not superior to SVi in the hemodynamic classification of severe AS.

Passive leg raising as an indicator of fluid responsiveness in patients with severe sepsis

BACKGROUND

In the management of critically ill patients, the assessment of volume responsiveness and the decision to administer a fluid bolus constitute a common dilemma for physicians. Static indices of cardiac preload are poor predictors of volume responsiveness. Passive leg raising (PLR) mimics an endogenous volume expansion (VE) that can be used to predict fluid responsiveness. This study was to assess the changes in stroke volume index (SVI) induced by PLR as an indicator of fluid responsiveness in mechanically ventilated patients with severe sepsis.

METHODS

This was a prospective study. Thirty-two mechanically ventilated patients with severe sepsis were admitted for VE in ICU of the First Affiliated Hospital, Zhejiang University School of Medicine and Ningbo Medical Treatment Center Lihuili Hospital from May 2010 to December 2011. Patients with non-sinus rhythm or arrhythmia, parturients, and amputation of the lower limbs were excluded. Measurements of SVI were obtained in a semi-recumbent position (baseline) and during PLR by the technique of pulse indicator continuous cardiac output (PiCCO) system prior to VE. Measurements were repeated after VE (500 mL 6% hydroxyethyl starch infusion within 30 minutes) to classify patients as either volume responders or non-responders based on their changes in stroke volume index (ΔSVI) over 15%. Heart rate (HR), systolic artery blood pressure (ABPs), diastolic artery blood pressure (ABPd), mean arterial blood pressure (ABPm), mean central venous pressure (CVPm) and cardiac index (CI) were compared between the two groups. The changes of ABPs, ABPm, CVPm, and SVI after PLR and VE were compared with the indices at the baseline. The ROC curve was drawn to evaluate the value of ΔSVI and the change of CVPm (ΔCVPm) in predicting volume responsiveness. SPSS 17.0 software was used for statistical analysis.

RESULTS

Among the 32 patients, 22 were responders and 10 were non-responders. After PLR among the responders, some hemodynamic variables (including ABPs, ABPd, ABPm and CVPm) were significantly elevated (101.2±17.6 vs.118.6±23.7, P=0.03; 52.8±10.7 vs. 64.8±10.7, P=0.006; 68.3±11.7 vs. 81.9±14.4, P=0.008; 6.8±3.2 vs. 11.9±4.0, P=0.001). After PLR, the area under curve (AUC) and the ROC curve of ΔSVI and ΔCVPm for predicting the responsiveness after VE were 0.882±0.061 (95%CI 0.759-1.000) and 0.805±0.079 (95%CI 0.650-0.959) when the cut-off levels of ΔSVI and ΔCVPm were 8.8% and 12.7%, the sensitivities were 72.7% and 72.7%, and the specificities were 80% and 80%.

CONCLUSION

Changes in ΔSVI and ΔCVPm induced by PLR are accurate indices for predicting fluid responsiveness in mechanically ventilated patients with severe sepsis.