Importance of exercise capacity in predicting outcomes and determining optimal timing of surgery in significant primary mitral regurgitation

BACKGROUND

In primary mitral regurgitation (MR), exercise echocardiography aids in symptom evaluation and timing of mitral valve (MV) surgery. In patients with grade ≥3 primary MR undergoing exercise echocardiography followed by MV surgery, we sought to assess predictors of outcomes and whether delaying MV surgery adversely affects outcomes.

METHODS AND RESULTS

We studied 576 consecutive such patients (aged 57±13 years, 70% men, excluding prior valve surgery and functional MR). Clinical, echocardiographic (MR, LVEF, indexed LV dimensions, RV systolic pressure) and exercise data (metabolic equivalents) were recorded. Composite events of death, MI, stroke, and congestive heart failure were recorded. Mean LVEF was 58±5%, indexed LV end-systolic dimension was 1.7±0.5 mm/m(2), rest RV systolic pressure was 32±13 mm Hg, peak-stress RV systolic pressure was 47±17 mm Hg, and percentage of age- and gender-predicted metabolic equivalents was 113±27. Median time between exercise and MV surgery was 3 months (MV surgery delayed ≥1 year in 28%). At 6.6±4 years, there were 53 events (no deaths at 30 days). On stepwise multivariable survival analysis, increasing age (hazard ratio of 1.07 [95% confidence interval, 1.03 to 1.12], P<0.01), lower percentage of age- and gender-predicted metabolic equivalents (hazard ratio of 0.82 [95% confidence interval, 0.71 to 0.94], P=0.007), and lower LVEF (0.94 [0.89 to 0.99], P=0.04) independently predicted outcomes. In patients achieving >100% predicted metabolic equivalents (n=399), delaying surgery by ≥1 year (median of 28 months) did not adversely affect outcomes (P=0.8).

CONCLUSION

In patients with primary MR that underwent exercise echocardiography followed by MV surgery, lower achieved metabolic equivalents were associated with worse long-term outcomes. In those with preserved exercise capacity, delaying MV surgery by ≥1 year did not adversely affect outcomes.

Echocardiographic Predictors of Reverse Remodeling After Cardiac Resynchronization Therapy and Subsequent Events

Background—

Studies of echocardiographic predictors of response after cardiac resynchronization therapy (CRT) have largely involved single parameters. We hypothesized that combining parameters would be more robust and sought to develop a multiparametric echocardiographic score for predicting CRT response.

Methods and Results—

Global longitudinal strain of left ventricle was added to standard echocardiographic measurements in 334 consecutive patients (224 men; mean, 65±12 years) who underwent baseline echocardiography before CRT and underwent follow-up echocardiograms at 1 year. Regression analysis was performed to create an echocardiographic score for prediction of LV reverse remodeling (defined as ≥15% reduction in the LV end-systolic volume). Cox proportional hazards models were used to identify the association of the score with death, transplantation or LV assist device implantation, and heart failure hospitalization during 57±22 months of follow-up. LV reverse remodeling (n=161; 48%) was associated with pre-CRT LV end-diastolic dimension index <3.1 cm/m 2 , global longitudinal strain of left ventricle <–7%, left atrial area <26 cm 2 , right ventricular end-diastolic area index <10.0 cm 2 /m 2 , right atrial area <20 cm 2 , and right ventricular fractional area change ≥35%. Combination of these into an echocardiographic score allowed prediction of LV reverse remodeling with a sensitivity of 84% and a specificity of 79%. During follow-up, there were 134 deaths, 18 heart transplantations/LV assist device implantations, and 93 heart failure admissions. The score was associated with heart failure admission, heart transplantation/LV assist device, or death (hazard ratio, 0.97; 95% confidence interval, 0.95–0.98; P <0.001) and all-cause death (hazard ratio, 0.97; 95% confidence interval, 0.96–0.98; P <0.001), independent of age, sex, ischemic cause, and initial functional class.

Conclusions—

A multiparametric echocardiographic score is helpful in selecting patients likely to undergo reverse remodeling after CRT and predicts clinical outcomes.

Effect of age, gender, and left ventricular diastolic function on left atrial volume index in adults without known cardiovascular disease or risk factors

There are limited data on reference values of left atrial volume indexes (LAVIs) in adults without known cardiovascular disease or risk factors, as well as their stratification by age, gender, and diastolic stage. LAVIs were calculated using the biplane area-length method in accordance with guidelines in 966 consecutive patients (mean age 48.0 ± 15.7 years) with no known cardiovascular disease or risk factors, with preserved left ventricular systolic function and normal or grade I diastolic dysfunction (DD). The mean LAVI was 23 ± 8 ml/m(2). Using a conventional cut-off value of 34 ml/m(2) (mean + 2 SDs of the values derived from the guidelines) to define abnormal LAVI would label about 10% of patients as having dilated left atria and structural heart disease, whereas using the American Society of Echocardiography's recommended cutoff of the mean + 1 SD (i.e., 28 ml/m(2)) would do so for up to about 20%. The mean LAVI was similar between the genders (p = 0.10) and among different age groups (p = 0.60 for the trend across decades). Finally, when stratified by diastolic function, the mean LAVIs were 23.2 ± 8.3 and 22.2 ± 8.7 ml/m(2) for patients with normal (n = 653) and grade I DD (n = 313), respectively (p = 0.10). In conclusion, in this cohort of patients without known cardiovascular disease or risk factors, the cut-off values for abnormal LAVI were greater than those adopted in the guidelines. There was no variation, however, by gender, age, or grade I DD, although subjects with long-standing grade I DD and/or high filling pressures were likely underrepresented.

Association of myocardial deformation with outcome in asymptomatic aortic stenosis with normal ejection fraction

BACKGROUND

Current guidelines recommend intervention for symptomatic aortic stenosis, but the management of asymptomatic aortic stenosis remains controversial. As left ventricular global longitudinal strain (GLS) has been shown to predict cardiovascular outcome, we sought to find whether its use could guide the assessment of risk in these patients.

METHODS AND RESULTS

We prospectively followed 79 patients with severe asymptomatic aortic stenosis (39 men; mean age, 77 ± 12 years; aortic valve [AV] area index, 0.36 cm(2)/m(2)). In addition to standard echocardiography, speckle strain was measured to assess GLS. Patients were followed for cardiac death and AV replacement driven by symptom development. A multivariable Cox regression was performed to identify associations with events. During 23 ± 20 months, 3 patients had cardiac death and 49 underwent AV replacement. Event-free survival was 72 ± 5% at 1 year, 50 ± 5% at 2 years, and 24 ± 5% at 4 years. Death and AV replacement were predicted by GLS (hazard ratio [HR], 1.14 [95% CI, 1.01-1.28]; P=0.037), as well as extent of AV calcification (HR, 2.44 [95% CI, 1.17-5.12]; P=0.018), peak transaortic pressure gradient (HR, 1.03 [95% CI, 1.01-1.04]; P<0.001), valvulo-arterial impedance (HR, 1.32 [95% CI, 1.04-1.67]; P=0.045), and Society of Thoracic Surgeons Predicted Risk of Morbidity and Mortality (HR, 0.95 [95% CI, 0.90-1.00]; P=0.052). A mean absolute GLS <15% was associated with a significant excess mortality, and this measurement added incremental prognostic value to the Society of Thoracic Surgeons Predicted Risk of Morbidity and Mortality, transaortic peak pressure gradient, AV calcification, and valvulo-arterial impedance.

CONCLUSIONS

GLS is associated with outcomes in patients with severe asymptomatic aortic stenosis, incremental to other clinical and echocardiographic variables.

Development of a consensus document to improve multireader concordance and accuracy of aortic regurgitation severity grading by echocardiography versus cardiac magnetic resonance imaging

Current guidelines recommend a multiparametric echocardiographic assessment of aortic regurgitation (AR). However, the absence of a hierarchical weighting of discordant parameters could cause interobserver variability. In the present study, we sought to define and improve the interobserver variability of AR assessment. Seventeen level 3 readers graded 20 randomly selected patients with AR. The readers also provided a usefulness score for each parameter, depending on its influence on their decision of the AR severity grade. A consensus strategy was subsequently formulated and validated against cardiac magnetic resonance imaging in a separate group of 80 patients. The readers were updated with the consensus document and recalibrated using the same cases. Agreement was statistically assessed using Randolph's free-marginal multirater kappa. At baseline, no uniform approach was used to combine the individual parameters, contributing to the interobserver variability (overall kappa 0.5). A consensus strategy to categorize AR severity was developed in which the left ventricular volume took precedence over the other parameters and was used to differentiate chronic severe AR from less severe categories. Recalibration of the readers using this consensus strategy improved concordance (kappa increased to 0.7). The new strategy also improved the accuracy relative to cardiac magnetic resonance imaging, as evidenced by full agreement on severe AR between the consensus document-based grading and AR severity defined by cardiac magnetic resonance imaging in the separate validation group of 80 patients. In conclusion, grading of chronic AR using a multiparametric approach has suboptimal consistency between readers and a left ventricular volume-based consensus document improved concordance and accuracy.

Impact of body mass index on diastolic function in patients with normal left ventricular ejection fraction

Background:

Obesity is a major public health epidemic and is associated with increased risk of heart failure and mortality. We evaluated the impact of body mass index (BMI) on the prevalence of diastolic dysfunction (DD).

Methods:

We reviewed clinical records and echocardiogram of patients with baseline echocardiogram between 1996 and 2005 that showed normal left ventricular ejection fraction (LVEF). Diastolic function was labeled as normal, stage 1, stage 2 or stage 3/4 dysfunction. Patients were categorized as normal weight (BMI <25 kg m⁻²), overweight (25–29.9 kg m⁻²), obese (30–39.9 kg m⁻²) and morbidly obese (⩾40 kg m⁻²). Multivariable ordinal and ordinary logistic regression were performed to identify factors associated with DD, and evaluate the independent relationship of BMI with DD.

Results:

The cohort included 21 666 patients (mean (s.d.) age, 57.1 (15.1); 55.5% female). There were 7352 (33.9%) overweight, 5995 (27.6%) obese and 1616 (7.4%) morbidly obese patients. Abnormal diastolic function was present in 13 414 (61.9%) patients, with stage 1 being the most common. As BMI increased, the prevalence of normal diastolic function decreased (P<0.0001). Furthermore, there were 1733 patients with age <35 years; 460 (26.5%) and 407 (23.5%) were overweight and obese, respectively, and had higher prevalence of DD (P<0.001). Using multivariable logistic regression, BMI remained significant in both ordinal (all stages of diastolic function) and binary (normal versus abnormal). Also, obesity was associated with increased odds of DD in all patients and those aged <35 years.

Conclusions:

In patients with normal LVEF, higher BMI was independently associated with worsening DD.

Relationship between baseline resting diastolic function and exercise capacity in patients with hypertrophic cardiomyopathy undergoing treadmill stress echocardiography: a cohort study

OBJECTIVE

Diastolic dysfunction (DD) is often incriminated in the symptomatology of patients with hypertrophic cardiomyopathy (HCM), but with limited supporting data. This study sought to assess the relationship between baseline diastolic function and exercise capacity in patients with HCM.

DESIGN

Retrospective study.

SETTING

Tertiary referral centre from Cleveland, Ohio, USA.

PARTICIPANTS

695 consecutive patients with a diagnosis of HCM who underwent exercise stress echocardiography between 1996 and 2011.

PRIMARY AND SECONDARY OUTCOME MEASURES

Diastolic function was reassessed from the resting echocardiograms by two blinded board-certified cardiologists. Maximal metabolic equivalents (MET) were extracted from the records. Multivariate regression analysis was performed to determine independent predictors of METs achieved.

RESULTS

Of 695 patients, 130 were excluded because of inability to assess diastolic function. There was no significant difference in maximal METs achieved between those excluded and included in the analysis (p=0.80). There were 495 remaining patients with a mean age (SD) of 50 (15) years, and 32% women among whom 102 (21%) had normal diastolic function, 243 (49%) stage 1 DD; 131 (26%) stage 2 DD and 19 (4%) stage 3 DD. Patients with advanced DD had lower maximal METs achieved compared with those with normal diastolic function (OR 3.18(1.96 to 5.14) for stage 1 versus normal, and 3.21(1.89 to 5.43) for stage ≥2 versus normal, p<0.0001 for both). After adjustment for demographics, comorbidities, echocardiographic parameters and haemodynamics, baseline DD was not an independent predictor of maximal METs achieved.

CONCLUSIONS

Although baseline DD is common in patients with HCM, it does not predict maximal METs achieved beyond traditional risk factors.

Impact of Mitral Regurgitation on Reverse Remodeling and Outcome in Patients Undergoing Cardiac Resynchronization Therapy

Background—

Mitral regurgitation (MR) is associated with reduced survival in patients with chronic heart failure, but may be improved with cardiac resynchronization therapy (CRT). We sought to evaluate the relationship between serial measurements of functional MR and reverse remodeling and outcomes in patients undergoing CRT.

Methods and Results—

A total of 266 consecutive patients undergoing CRT with available baseline echocardiograms and subsequent clinical and echocardiographic follow-up were included in the analysis. Long-term follow-up included all-cause mortality, heart transplantation, and implantation of a left ventricular (LV) assist device. Temporal changes in MR severity and LV end-systolic volume index (LVESVi) were evaluated by linear mixed-model analysis. CRT led to an immediate sustained decrease in MR ( P <0.0001), with no significant subsequent change. The amount of MR decrease correlated with a greater decrease in LVESVi late ( P ≤0.0001), but not early ( P =0.14), after CRT began. Patients with severe MR before CRT experienced a larger LVESVi decrease ( P =0.005). Although baseline MR severity was not associated with adverse events ( P =0.13), a larger MR decrease ( P =0.001) and a smaller residual MR after the initial 6 months of CRT ( P =0.03) were predictive of better outcome in a multivariable model.

Conclusions—

Early reversal of functional MR was associated with reverse cardiac remodeling and improved outcomes. Patients with moderately severe to severe MR before CRT experienced relatively more reverse remodeling than patients with lesser degrees of MR.

The impact of left ventricular size on response to cardiac resynchronization therapy

Patients with nondilated (NDCM) or severely dilated cardiomyopathies (SDCM) have been underrepresented in clinical trials of cardiac resynchronization therapy (CRT). We examined changes in left ventricular ejection fraction (LVEF) and survival in patients with NDCM or SDCM compared with those with traditionally studied moderately dilated cardiomyopathy.

METHODS

We evaluated 800 consecutive patients undergoing the original implantation of a biventricular pacemaker between January 2004 and August 2007. For inclusion, patients had a baseline and pre-CRT echocardiogram, an LVEF ≤40%, a US social security number, and New York Heart Association class II to IV symptoms on standard medical therapy. Patients with a follow-up echocardiogram >2 months after device implantation were included in an analysis of remodeling. Using multivariate models, the impact of baseline left ventricular end-diastolic diameter (LVEDD) on change in LVEF and all-cause mortality was assessed.

RESULTS

A total of 668 patients met inclusion criteria and were included in the assessment of mortality. Four hundred seventy-one had an appropriately timed follow-up echocardiogram and were included in the analysis of remodeling. Patients in all 3 groups realized improvements in LVEF (%) after CRT as follows: NDCM (n = 137; LVEDD ≤5.5 cm) 10.0 ± 12.7, P < .001; moderately dilated cardiomyopathy (n = 233; LVEDD 5.6-6.9 cm) 8.2 ± 11.3, P < .001; and SDCM (n = 101; LVEDD ≥7.0 cm) 5.4 ± 9.4, P < .001. In multivariate analysis, baseline LVEDD was inversely associated with change in LVEF (parameter estimate -3.13 ± 0.56, P < .001) and directly associated with increased all-cause mortality (hazard ratio 1.25 [1.05-1.47] P = .01).

CONCLUSION

Patients with NDCM and SDCM experience significant improvements in LVEF after CRT. The degree of baseline left ventricular dilatation before CRT is an important predictor of subsequent changes in LVEF and survival.

QRS fragmentation is not associated with poor response to cardiac resynchronization therapy

BACKGROUND

QRS fragmentation (fQRS) has been shown to be a marker of scar in patients with left ventricular dysfunction. Whether fQRS is associated with progressive left ventricular remodeling and increased mortality in patients receiving cardiac resynchronization therapy (CRT) is unclear.

METHODS

We reviewed the preimplant and follow-up echocardiograms in 233 patients undergoing the new implantation of a CRT device between December 2001 and November 2006. Patients were included if they had a pre-CRT ECG with appropriate filter settings (filter 0.16-100 or 0.16-150 Hz, 25 mm/s, 10 mm/mV), a left ventricular ejection fraction (LVEF) ≤40%, and New York Heart Association class II-IV symptoms on standard medical therapy. The 12-lead electrocardiogram (ECG) was interpreted by two blinded reviewers for the presence of fQRS. Remodeling end points, including changes in LVEF and left ventricular end-diastolic (LVEDV) and systolic (LVESV) volumes, were compared between patients with and without contiguous fQRS, and an assessment of all-cause mortality was made.

RESULTS

Two hundred thirty-two patients met inclusion criteria, of which 50 demonstrated fQRS in contiguous leads. There was no difference in improvement in LVEF (%) (7.9 ± 12.9 vs 6.8 ± 11.0, P = 0.60) or reduction in LVEDV (mL) (-30.1 ± 57.2 vs -15.7 ± 47.6) or LVESV (mL) (-33.7 ± 58.1 vs -22.7 ± 50.6, P = 0.40) between patients with and without contiguous fQRS. At a mean follow-up of 4.4 ± 1.9 years, there were a total of 89 deaths, 22 (44.0%) in patients with contiguous fQRS and 67 (36.8%) without (log rank P = 0.31).

CONCLUSIONS

QRS fragmentation is not a predictor of progressive ventricular remodeling or mortality in heart failure patients undergoing CRT.

Impact of Longitudinal Cardiac Rotation on Mitral and Tricuspid Atrioventricular Annular Diastolic Motion

Background—

It is unknown whether longitudinal rotation (LR), often seen in cardiac resynchronization therapy candidates, may affect mitral annular early diastolic (E′) velocities and tricuspid annular motion. We assessed whether (1) LR affects the amplitude and timing of septal and lateral mitral annular E′ velocities and tricuspid annular systolic and E′ velocities and (2) if systolic strain heterogeneity seen in cardiac resynchronization therapy patients with LR extends into diastole.

Methods and Results—

Ninety-nine cardiac resynchronization therapy candidates with suitable baseline echocardiograms were identified. Early diastolic (E′) and systolic myocardial velocities of the tricuspid annulus and E′ velocities of the septal and lateral part of the mitral annulus were analyzed from tissue Doppler images. Longitudinal rotation and basal systolic and diastolic strain rates were analyzed by speckle-tracking. LR correlated with lateral mitral annular E′ ( r =0.45, P <0.001), tricuspid annular E′ ( r =−0.3, P =0.003), and with a difference between septal and lateral mitral annular E′ velocities ( r =−0.49, P <0.001) but not with septal mitral annular E′ velocity. LR also correlated with tricuspid annular systolic velocity ( r =0.60, P <0.001). After categorizing the patients according to the quartiles of their LR, we showed that with decreasing quartile number, heterogeneity of systolic ( P =0.003) but not diastolic ( P >0.1) strain rates increased.

Conclusions—

LR direction and magnitude correlates with the amplitude of, and relative differences between, diastolic velocities of tricuspid, lateral mitral, and septal mitral annulus, which are a cornerstone of diastolic function assessment. LR is associated with systolic but not with diastolic regional heterogeneity.

Long-term reverse remodeling with cardiac resynchronization therapy: results of extended echocardiographic follow-up

OBJECTIVES

The purpose of this study was to describe the long-term course of left ventricular remodeling induced by cardiac resynchronization therapy (CRT), adjusting for the confounding effect of patient loss due to disease.

BACKGROUND

Reverse remodeling has been identified as the primary mechanism of improved symptoms and outcome in heart failure patients.

METHODS

A total of 313 consecutive patients who underwent CRT with available baseline echocardiograms and subsequent clinical and echocardiographic follow-up were included in the analysis. Long-term follow-up included all-cause mortality, heart transplantation, and implantation of a left ventricular assist device. Longitudinal data analysis of left ventricular end-systolic volume index (LVESVi) was performed to adjust for the confounding effect of patient loss during follow-up.

RESULTS

Patients with uneventful survival had a lower baseline LVESVi (Delta = 8.6 ml/m(2), SE = 4.6 ml/m(2), p < 0.0001) and a decreased LVESVi by -0.11 ml/m(2)/day during first 6 months, whereas the LVESVi remained unchanged in patients with adverse events (p < 0.0001). Beyond 6 months, the LVESVi remained unchanged in patients with uneventful survival, whereas the LVESVi continued to increase in those with adverse events at a rate of 0.01 ml/m(2)/day (p < 0.0001). Predictors of reverse remodeling were nonischemic etiology, female sex, and a wider QRS duration (p < 0.0001, p = 0.014, and p = 0.001, respectively). In the majority of patients, 6 months indicates a break point after which reverse remodeling becomes significantly less pronounced.

CONCLUSIONS

CRT patients with uneventful survival show a significant decrease in the LVSVi at 6 months and generally maintain this response in the long term. Those with adverse outcomes are characterized by left ventricular dilation despite CRT.