Myocardial Contraction Fraction: A Volumetric Measure of Myocardial Shortening Analogous to Strain

Temporal outcomes of patients diagnosed with transthyretin cardiac amyloidosis

BACKGROUND

Transthyretin cardiac amyloidosis (ATTR-CA) is increasingly recognized. Clinical outcomes have evolved over time amidst changes in the diagnostic pathway and advances in therapeutics.

OBJECTIVE

To evaluate clinical outcomes over time of ATTR-CA patients with access to disease-modifying therapy.

METHODS

This is a retrospective cohort study of 419 patients diagnosed with ATTR-CA during 2001-2021, comparing clinical characteristics across eras. The primary endpoint was composite all-cause mortality or orthotopic heart transplant (OHT). Time-to-event analysis was performed using Cox proportional hazard modeling controlling for differences amongst cohorts.

RESULTS

Patients diagnosed in the more recent years had higher median age (2017-2021: 78 years, 2014-2016: 75 years, 2001-2013: 74 years) and more often had ATTRwt (81.9% vs 82.5% vs. 56.4%) but less severe phenotypes as evidenced by more individuals with Columbia stage I disease (47.6% vs 35.9% vs 22.4%), due to lower biomarkers, more NYHA Class I-II patients (68.9% vs 47.6% vs. 43.6%), and lower use of loop diuretics (67.0% vs 78.6% vs 89.1%). Over time, patients were more frequently treated with Tafamidis (74% vs 37% vs 32%). On multivariable analysis, greater Columbia score (HR 1.42, 95% CI 1.30-1.54, p<0.001) was predictive of death or OHT, while Tafamidis (HR 0.31, 95% CI 0.22-0.44, p<0.001) was associated with greater survival and freedom from OHT.

CONCLUSIONS

Recently diagnosed ATTR-CA patients have earlier stage disease and substantially lower mortality. Tafamidis is associated with significantly improved survival and freedom from OHT.

Quantification of Myocardial Contraction Fraction with Three-Dimensional Automated, Machine-Learning-Based Left-Heart-Chamber Metrics: Diagnostic Utility in Hypertrophic Phenotypes and Normal Ejection Fraction

Aims: The differentiation of left ventricular (LV) hypertrophic phenotypes is challenging in patients with normal ejection fraction (EF). The myocardial contraction fraction (MCF) is a simple dimensionless index useful for specifically identifying cardiac amyloidosis (CA) and hypertrophic cardiomyopathy (HCM) when calculated by cardiac magnetic resonance. The purpose of this study was to evaluate the value of MCF measured by three-dimensional automated, machine-learning-based LV chamber metrics (dynamic heart model [DHM]) for the discrimination of different forms of hypertrophic phenotypes. Methods and Results: We analyzed the DHM LV metrics of patients with CA (n = 10), hypertrophic cardiomyopathy (HCM, n = 36), isolated hypertension (IH, n = 87), and 54 healthy controls. MCF was calculated by dividing LV stroke volume by LV myocardial volume. Compared with controls (median 61.95%, interquartile range 55.43-67.79%), mean values for MCF were significantly reduced in HCM-48.55% (43.46-54.86% p < 0.001)-and CA-40.92% (36.68-46.84% p < 0.002)-but not in IH-59.35% (53.22-64.93% p < 0.7). MCF showed a weak correlation with EF in the overall cohort (R2 = 0.136) and the four study subgroups (healthy adults, R2 = 0.039 IH, R2 = 0.089; HCM, R2 = 0.225; CA, R2 = 0.102). ROC analyses showed that MCF could differentiate between healthy adults and HCM (sensitivity 75.9%, specificity 77.8%, AUC 0.814) and between healthy adults and CA (sensitivity 87.0%, specificity 100%, AUC 0.959). The best cut-off values were 55.3% and 52.8%. Conclusions: The easily derived quantification of MCF by DHM can refine our echocardiographic discrimination capacity in patients with hypertrophic phenotype and normal EF. It should be added to the diagnostic workup of these patients.

The First Dedicated Comprehensive Heart Failure Program in the United States: The Division of Circulatory Physiology at Columbia Presbyterian (1992-2004)

The first dedicated multidisciplinary heart failure program in the United States was founded as the Division of Circulatory Physiology at the Columbia University College of Physicians & Surgeons in 1992. The Division was administratively and financially independent of the Division of Cardiology and grew to 24 faculty members at its peak. Its administrative innovations included (1) a comprehensive full-integrated service line, with 2 differentiated clinical teams, one devoted to drug therapy and the other to heart transplantation and ventricular assist devices; (2) a nurse specialist/physician assistant-led clinical service; and (3) a financial structure independent of (and not supported by) other cardiovascular medical or surgical services. The division had 3 overarching missions: (1) to promote a unique career development path for each faculty member to be linked to recognition in a specific area of heart failure expertise; (2) to change the trajectory and enhance the richness of intellectual discourse in the discipline of heart failure, so as to foster an understanding of fundamental mechanisms and to develop new therapeutics; and (3) to provide optimal medical care to patients and to promote the ability of other physicians to provide optimal care. The major research achievements of the division included (1) the development of beta-blockers for heart failure, from initial hemodynamic assessments to proof-of-concept studies to large-scale international trials; (2) the development and definitive assessment of flosequinan, amlodipine, and endothelin antagonists; (3) initial clinical trials and concerns with nesiritide; (4) large-scale trials evaluating dosing of angiotensin converting-enzyme inhibitors and the efficacy and safety of neprilysin inhibition; (5) identification of key mechanisms in heart failure, including neurohormonal activation, microcirculatory endothelial dysfunction, deficiencies in peripheral vasodilator pathways, noncardiac factors in driving dyspnea, and the first identification of subphenotypes of heart failure and a preserved ejection fraction; (6) the development of a volumetric approach to the assessment of myocardial shortening; (7) conceptualization and early studies of cardiac contractility modulation as a treatment for heart failure; (8) novel approaches to the identification of cardiac allograft rejection and new therapeutics to prevent allograft vasculopathy; and (9) demonstration of the effect of left ventricular assist devices to induce reverse remodeling, and the first randomized trial showing a survival benefit with ventricular assist devices. Above all, the division served as an exceptional incubator for a generation of leaders in the field of heart failure.

Echocardiographic findings in cardiogenic shock due to acute myocardial infarction versus heart failure

BACKGROUND

Acute myocardial infarction (AMI) is the prototypical cause of cardiogenic shock (CS), yet CS due to heart failure (HF-CS) is increasingly common. Little is known regarding cardiac function in AMI-CS versus HF-CS. We compared transthoracic echocardiography (TTE) findings in AMI-CS versus HF-CS and identified predictors of mortality in AMI-CS patients.

METHODS

We performed a single-center, retrospective analysis of CS admissions between 2007 and 2018. We compared baseline demographic and TTE parameters in patients with AMI-CS and HF-CS as well as ST elevation myocardial infarction (STEMI)-CS versus non-ST elevation myocardial infarction (NSTEMI)-CS.

RESULTS

We included 893 unique patients, including 581 (65%) with AMI-CS. AMI-CS patients were older but had lower illness severity and non-cardiac comorbidity burden. AMI-CS patients had better left ventricular function (LVEF 35% versus 28%), lower biventricular filling pressures, and higher stroke volume versus those with HF-CS. Among TTE measurements, myocardial contraction fraction had the highest discrimination for mortality in AMI-CS (AUC: 0.64); AUC values for LVEF and SOFA score were 0.61 and 0.65, respectively. Differences in TTE findings between STEMI-CS versus NSTEMI-CS were modest. There were no significant differences in unadjusted or adjusted in-hospital mortality between AMI-CS and HF-CS (31% versus 35%) or STEMI-CS and NSTEMI-CS (31% versus 30%) groups (all p > 0.05).

CONCLUSIONS

Patients with HF-CS and AMI-CS differ in terms of clinical and TTE variables yet have similar prognoses. TTE is useful in determining prognosis of patients admitted with AMI-CS and may allow for early triage and directed therapy.

A Review of Current and Evolving Imaging Techniques in Cardiac Amyloidosis

Purpose of review

Establishing an early, efficient diagnosis for cardiac amyloid (CA) is critical to avoiding adverse outcomes. We review current imaging tools that can aid early diagnosis, offer prognostic information, and possibly track treatment response in CA.

Recent findings

There are several current conventional imaging modalities that aid in the diagnosis of CA including electrocardiography, echocardiography, bone scintigraphy, cardiac computed tomography (CT), and cardiac magnetic resonance (CMR) imaging. Advanced imaging techniques including left atrial and right ventricular strain, and CMR T1 and T2 mapping as well as ECV quantification may provide alternative non-invasive means for diagnosis, more granular prognostication, and the ability to track treatment response.

Summary

Leveraging a multimodal imaging toolbox is integral to the early diagnosis of CA; however, it is important to understand the unique role and limitations posed by each modality. Ongoing studies are needed to help identify imaging markers that will lead to an enhanced ability to diagnose, subtype and manage this condition.

Clinical significance of myocardial contraction fraction in significant primary mitral regurgitation

BACKGROUND

The optimal timing for mitral valve (MV) surgery in asymptomatic patients with primary mitral regurgitation (MR) remains a matter of debate. Myocardial contraction fraction (MCF) - the ratio of the left ventricular (LV) stroke volume to that of the myocardial volume - is a volumetric measure of LV myocardial shortening independent of size or geometry.

AIM

To assess the relationship between MCF and outcome in patients with significant chronic primary MR due to prolapse managed in contemporary practice.

METHODS

Clinical, Doppler-echocardiographic and outcome data prospectively collected in 174 patients (mean age 62 years, 27% women) with significant primary MR and no or mild symptoms were analysed. The impact of MCF< or ≥30% on cardiac events (cardiovascular death, acute heart failure or MV surgery) was studied.

RESULTS

During an estimated median follow-up of 49 (22-77) months, cardiac events occurred in 115 (66%) patients. The 4-year estimates of survival free from cardiac events were 21±5% for patients with MCF <30% and 40±6% for those with ≥30% (P<0.001). MCF <30% was associated with a considerable increased risk of cardiac events after adjustment for established clinical risk factors, MR severity and current recommended class I triggers for MV surgery (adjusted hazard ratio: 2.33, 95% confidence interval: 1.51-3.58; P<0.001). Moreover, MCF<30% improved the predictive performance of models, with better global fit, reclassification and discrimination.

CONCLUSIONS

MCF<30% is strongly associated with occurrence of cardiac events in patients with significant primary MR due to prolapse. Further studies are needed to assess the direct impact of MCF on patient management and outcomes.

Predictive value of cardiac magnetic resonance mechanical parameters for myocardial fibrosis in hypertrophic cardiomyopathy with preserved left ventricular ejection fraction

Objective

Myocardial fibrosis leads to systolic dysfunction in hypertrophic cardiomyopathy (HCM) patients. This study aims to investigate the relationship between cardiac magnetic resonance mechanical parameters for evaluating the left ventricular function in HCM with preserved left ventricular ejection fraction (LVEF ≥50%) and the association between myocardial fibrosis defined by late gadolinium enhancement (LGE).

Methods

This study was a retrospective analysis of CMR images of 93 patients with HCM with preserved ejection fraction (HCMpEF) and 96 controls diagnosed by cardiac magnetic resonance (CMR) at our hospital from July 2019 to January 2022. The myocardial contraction fraction (MCF) was calculated, and myocardial mechanical parameters, including global myocardial longitudinal strain (GLS), circumferential strain (GLS), and myocardial strain (GLS), were obtained by tissue tracking and LGE quantitative modules of dedicated software, respectively. The correlation between myocardial strain and LGE was analyzed, and a multivariate logistic regression model was developed to discuss the risk predictors of LGE.

Results

Compared to the control group, the left ventricular mechanical parameters GLS (-13.90 ± 3.80% versus -18.20 ± 2.10%, p < 0.001), GCS (-16.62 ± 3.50% versus -18.4 ± 2.69%, p < 0.001), GRS (28.99 ± 10.38% versus 33.02 ± 6.25%, p < 0.01), and MCF (64 ± 16% versus 99 ± 18%, p < 0.001) were found significantly lower in HCM group. Moreover, even in LGE-negative HCM patients, GLS (-16.3 ± 3.9%) and MCF (78 ± 19%) were significantly lower compared to the control group. Left ventricular GLS [OR = 1.61, (1.29, 2.02), p = 0.001] and MCF [OR = 0.90, (0.86, 0.94), p = 0.001] independently predicted myocardial late gadolinium enhancement (LGE).

Conclusion

In participants of HCM with preserved ejection fraction, the early onset of reduced left ventricular GLS and MCF in patients with HCMpEF may provide new evidence for evaluating impaired myocardial systolic function. The reduction of myocardial mechanical indexes may reflect the presence and extent of myocardial fibrosis, and the more significant the reduction, the more severe the myocardial fibrosis; GLS and MCF may be ideal predictors for LGE.

Echocardiographic Characteristics of Cardiogenic Shock Patients with and Without Cardiac Arrest

BACKGROUND

Cardiac arrest (CA) is associated with worse outcomes in patients with cardiogenic shock (CS). To better understand the contribution of CA on CS, we evaluated transthoracic echocardiography (TTE) parameters in CS patients with and without CA. Methods: We retrospectively identified CS patients with a TTE performed near cardiac intensive care unit admission between 2007 to 2018. We compared TTE measurements of left ventricular (LV) and right ventricular (RV) function in patients with and without CA. The primary outcome was all-cause in-hospital mortality, as determined using multivariable logistic regression. Results: We included 1085 patients, 35% of whom had CA. Median age was 70 years and 37% were females. CA patients had higher severity of illness, more invasive mechanical ventilation and greater vasopressor/inotrope use. In-hospital mortality was 31% and was higher in CA patients (45% vs. 23%, p <0.001). Although LV ejection fraction (LVEF) was similar (35% vs. 37%, p = 0.05), CA patients had lower cardiac index, mitral valve E wave peak velocity, E/A ratio and E/e' ratio. TTE variables that were associated with hospital mortality varied, among patients with CA, these included measures of RV pressure and function and among patients without CA, these included parameters reflecting LV systolic function. Conclusions: Doppler assessments of RV systolic dysfunction were the strongest TTE predictors of hospital mortality in CS patients with CA, unlike CS patients without CA in whom LV systolic function was more important. This emphasizes the importance of RV assessment for mortality risk stratification after CA.

Echocardiographic left ventricular stroke work index: An integrated noninvasive measure of shock severity

Background

Echocardiographic findings vary with shock severity, as defined by the Society for Cardiovascular Angiography and Intervention (SCAI) shock stage. Left ventricular stroke work index (LVSWI) measured by transthoracic echocardiography (TTE) can predict mortality in the cardiac intensive care unit (CICU). We sought to determine whether LVSWI could refine mortality risk stratification by the SCAI shock classification in the CICU.

Methods

We included consecutive CICU patients from 2007 to 2015 with TTE data available to calculate the LVSWI, specifically the mean arterial pressure, stroke volume index and medial mitral E/e’ ratio. In-hospital mortality as a function of LVSWI was evaluated across the SCAI shock stages using logistic regression, before and after multivariable adjustment.

Results

We included 3635 unique CICU patients, with a mean age of 68.1 ± 14.5 years (36.5% females); 61.1% of patients had an acute coronary syndrome. The LVSWI progressively decreased with increasing shock severity, as defined by increasing SCAI shock stage. A total of 203 (5.6%) patients died during hospitalization, with higher in-hospital mortality among patients with lower LVSWI (adjusted OR 0.66 per 10 J/m2 higher) or higher SCAI shock stage (adjusted OR 1.24 per each higher stage). A LVSWI <33 J/m2 was associated with higher adjusted in-hospital mortality, particularly among patients with shock (SCAI stages C, D and E).

Conclusions

The LVSWI by TTE noninvasively characterizes the severity of shock, including both systolic and diastolic parameters, and can identify low-risk and high-risk patients at each level of clinical shock severity.

Myocardial contraction fraction by echocardiography and mortality in cardiac intensive care unit patients

BACKGROUND

The myocardial contraction fraction (MCF) is proposed as an improved measure of left ventricular (LV) systolic function that overcomes important limitations of the left ventricular ejection fraction (LVEF). We sought to determine whether a low MCF was associated with higher mortality in cardiac intensive care unit (CICU) patients.

METHODS

We retrospectively analyzed unique Mayo Clinic CICU patients from 2007 to 2018 with MCF calculated as the ratio of the stroke volume to the left ventricular myocardial volume from a transthoracic echocardiogram within 1 day of CICU admission. Multivariable logistic regression analyzed the association between MCF and hospital mortality, after adjustment for LVEF and clinical variables.

RESULTS

We included 4794 patients with a mean age of 68.0 ± 14.8 years (37.1% females). The mean MCF was 0.41 ± 0.16, and was lower in the 6.6% of patients who died in the hospital (0.32 ± 0.14 versus 0.42 ± 0.16, p < 0.001). On multivariable analysis, higher MCF remained associated with lower hospital mortality (adjusted OR 0.78 per 0.1 higher, 95% CI 0.69-0.89, p < 0.001), whereas LVEF was not significantly associated with hospital mortality (unadjusted OR 0.91 per 10% higher, OR 95% CI 0.82-1.02, p = 0.09). Patients with MCF <0.2 had the highest in-hospital mortality, and those with MCF ≥0.5 had the lowest in-hospital mortality, irrespective of admission diagnosis or LVEF.

CONCLUSIONS

MCF demonstrated a strong, inverse relationship with hospital mortality in CICU patients, even after adjusting for LVEF and clinical variables. MCF can be used to identify prognostically-relevant myocardial dysfunction at the bedside, even among patients with preserved LVEF.

Cardiopulmonary exercise testing in patients with Cardiac Amyloidosis

BACKGROUND

Cardiac involvement and dysfunction are common in patients presenting with AL and ATTR Amyloidosis. Cardiopulmonary exercise testing (CPET) performance is the gold standard to quantify functional capacity.

PATIENTS AND METHODS

In this study, we evaluated CPET measurements in 41 patients with cardiac Amyloidosis and their correlation with current amyloid specific staging criteria.

RESULTS

In both AL and ATTR cardiac Amyloidosis, percent predicted peak VO2 is significantly reduced and correlates with biomarker abnormalities. The association of cardiac biomarkers with peak VO2 is stronger for AL Amyloidosis (NT-proBNP (r = -0.57, P=0.006), Troponin (r = -0.70, p < 0.001) than ATTR (NT-proBNP (r = -0.4, P = 0.04) and Troponin (r = -0.57, P = 0.002) despite lower left ventricular mass in the former, suggesting that this may be further evidence for light chain toxicity in AL amyloidosis.

CONCLUSION

Our findings suggest further evidence for AL toxicity.

Prediction of Genotype Positivity in Patients With Hypertrophic Cardiomyopathy Using Machine Learning

BACKGROUND

Genetic testing can determine family screening strategies and has prognostic and diagnostic value in hypertrophic cardiomyopathy (HCM). However, it can also pose a significant psychosocial burden. Conventional scoring systems offer modest ability to predict genotype positivity. The aim of our study was to develop a novel prediction model for genotype positivity in patients with HCM by applying machine learning (ML) algorithms.

METHODS

We constructed 3 ML models using readily available clinical and cardiac imaging data of 102 patients from Columbia University with HCM who had undergone genetic testing (the training set). We validated model performance on 76 patients with HCM from Massachusetts General Hospital (the test set). Within the test set, we compared the area under the receiver operating characteristic curves (AUROCs) for the ML models against the AUROCs generated by the Toronto HCM Genotype Score (the Toronto score) and Mayo HCM Genotype Predictor (the Mayo score) using the Delong test and net reclassification improvement.

RESULTS

Overall, 63 of the 178 patients (35%) were genotype positive. The random forest ML model developed in the training set demonstrated an AUROC of 0.92 (95% CI, 0.85-0.99) in predicting genotype positivity in the test set, significantly outperforming the Toronto score (AUROC, 0.77 [95% CI, 0.65-0.90], P=0.004, net reclassification improvement: P<0.001) and the Mayo score (AUROC, 0.79 [95% CI, 0.67-0.92], P=0.01, net reclassification improvement: P=0.001). The gradient boosted decision tree ML model also achieved significant net reclassification improvement over the Toronto score (P<0.001) and the Mayo score (P=0.03), with an AUROC of 0.87 (95% CI, 0.75-0.99). Compared with the Toronto and Mayo scores, all 3 ML models had higher sensitivity, positive predictive value, and negative predictive value.

CONCLUSIONS

Our ML models demonstrated a superior ability to predict genotype positivity in patients with HCM compared with conventional scoring systems in an external validation test set.

Cardiac Amyloidosis: Overlooked, Underappreciated, and Treatable

Cardiac amyloidosis (CA) is an infiltrative and restrictive cardiomyopathy that leads to heart failure, reduced quality of life, and death. The disease has two main subtypes, transthyretin cardiac amyloidosis (ATTR-CA) and immunoglobulin light chain cardiac amyloidosis (AL-CA), characterized by the nature of the infiltrating protein. ATTR-CA is further subdivided into wild-type (ATTRwt-CA) and variant (ATTRv-CA) based on the presence or absence of a mutation in the transthyretin gene. CA is significantly underdiagnosed and increasingly recognized as a cause of heart failure with preserved ejection fraction. Advances in diagnosis that employ nuclear scintigraphy to diagnose ATTR-CA without a biopsy and the emergence of effective treatments, including transthyretin stabilizers and silencers, have changed the landscape of this field and render early and accurate diagnosis critical. This review summarizes the epidemiology, pathophysiology, diagnosis, prognosis, and management of CA with an emphasis on the significance of recent developments and suggested future directions.

Range Variability in CMR Feature Tracking Multilayer Strain across Different Stages of Heart Failure

Heart failure (HF) is associated with progressive ventricular remodeling and impaired contraction that affects distinctly various regions of the myocardium. Our study applied cardiac magnetic resonance (CMR) feature tracking (FT) to assess comparatively myocardial strain at 3 distinct levels: subendocardial (Endo-), mid (Myo-) and subepicardial (Epi-) myocardium across an extended spectrum of patients with HF. 59 patients with HF, divided into 3 subgroups as follows: preserved ejection fraction (HFpEF, N = 18), HF with mid-range ejection fraction (HFmrEF, N = 21), HF with reduced ejection fraction (HFrEF, N = 20) and a group of age- gender- matched volunteers (N = 17) were included. Using CMR FT we assessed systolic longitudinal and circumferential strain and strain-rate at Endo-, Myo- and Epi- levels. Strain values were the highest in the Endo- layer and progressively lower in the Myo- and Epi- layers respectively, this gradient was present in all the patients groups analyzed but decreased progressively in HFmrEF and further on in HFrEF groups. GLS decreased with the severity of the disease in all 3 layers: Normal > HFpEF > HFmrEF > HFrEF (Endo-: −23.0 ± 3.5 > −20.0 ± 3.3 > −16.4 ± 2.2 > −11.0 ± 3.2, p < 0.001, Myo-: −20.7 ± 2.4 > −17.5.0 ± 2.6 > −14.5 ± 2.1 > −9.6 ± 2.7, p < 0.001; Epi-: −15.7 ± 1.9 > −12.2 ± 2.1 > −10.6 ± 2.3 > −7.7 ± 2.3, p < 0.001). In contrast, GCS was not different between the Normal and HFpEF (Endo-: −34.5 ± 6.2 vs −33.9 ± 5.7, p = 0.51; Myo-: −21.9 ± 3.8 vs −21.3 ± 2.2, p = 0.39, Epi-: −11.4 ± 2.0 vs −10.9 ± 2.3, p = 0.54) but was, as well, markedly lower in the systolic heart failure groups: Normal > HFmrEF > HFrEF (Endo-: −34.5 ± 6.2 > −20.0 ± 4.2 > 12.3 ± 4.2, p < 0.001; Myo-: −21.9 ± 3.8 > −13.0 ± 3.4 > −8.0 ± 2.7. p < 0.001; Epi-: −11.4 ± 2.0 > −7.9 ± 2.3 > −4.5 ± 1.9. p < 0.001). CMR feature tracking multilayer strain assessment identifies large range differences between distinct myocardial regions. Our data emphasizes the importance of sub-endocardial myocardium for cardiac contraction and thus, its predilect role in imaging detection of functional impairment. CMR feature tracking offers a convenient, readily available, platform to evaluate myocardial contraction with excellent spatial resolution, rendering further details about discrete areas of the myocardium. Using this technique across distinct groups of patients with heart failure (HF), we demonstrate that subendocardial regions of the myocardium exhibit much higher strain values than mid-myocardium or subepicardial and are more sensitive to detect contractile impairment. We also show comparatively higher values of circumferential strain compared with longitudinal and a higher sensitivity to detect contractile impairment. A newly characterized group of patients, HF with mid-range ejection fraction (EF), shows similar traits of decompensation but has relatively higher strain values as patients with HF with reduced EF.

Association between reduced myocardial contraction fraction and cardiovascular disease outcomes: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

The myocardial contraction fraction (MCF: stroke volume to myocardial volume) is a volumetric measure of left ventricular myocardial shortening. We examined the relationship of MCF, measured by cardiac magnetic resonance imaging (cMRI), to incident cardiovascular (CV) events within the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

Participants (n = 5000, aged 45-84 years) underwent cMRI.

PRIMARY OUTCOME

CVD events (myocardial infarction, resuscitated cardiac arrest, stroke, coronary heart disease: CHD death, and stroke death).

SECONDARY OUTCOMES

CHD and heart failure (HF) events. Cox proportional hazards regression was used to estimate the hazard ratio (HR) and 95% confidence intervals (CI) for outcomes.

RESULTS

There were 299 incident CVD, 188 CHD, and 151 HF events over 10.2 years. The lowest MCF quartile was associated with an increased risk for incident CVD [HR 2.42, CI: 1.58-3.72], CHD [HR 2.32, CI: 1.36-3.96] and HF events [HR 1.99, CI: 1.15-3.44]. In a model adjusted for demographics, CV risk factors, antihypertensive and lipid-lowering medication use, each standard deviation decrease in MCF was associated with incident CVD [HR 1.42, CI: 1.23-1.64], CHD [HR 1.40, CI: 1.17-1.67] and HF [HR 1.58, CI: 1.30-1.94]. In a subgroup analysis of participants with preserved ejection fraction and without left ventricular hypertrophy, the lowest MCF quartile and each standard deviation decrease in MCF was also associated with an increased risk for incident CVD in fully-adjusted analyses.

CONCLUSIONS

MCF is a novel measure that can be measured using cMRI. In this multi-ethnic cohort, MCF is a measure that can be used to predict incident CVD events.

Myocardial Contraction Fraction by M-Mode Echocardiography Is Superior to Ejection Fraction in Predicting Mortality in Transthyretin Amyloidosis

BACKGROUND

Transthyretin amyloidosis (ATTR) is often associated with cardiac involvement manifesting as conduction disease as well as restrictive cardiomyopathy causing heart failure and death. Myocardial contraction fraction (MCF), the ratio of left ventricular stroke volume (SV) to myocardial volume (MV), is a volumetric measure of myocardial shortening that is superior to ejection fraction (EF) in predicting mortality in patients with primary amyloid light chain cardiac amyloidosis. We hypothesized that MCF would be an independent predictor of survival in TTR-CA.

METHODS AND RESULTS

MCF was derived from 2-dimensional echocardiography-guided M-mode data for 530 subjects in the Transthyretin Amyloidosis Outcomes Survey (THAOS) database: age 61 ± 16years, 74% male, 158 wild-type (ATTRwt) and 372 mutant (ATTRm), follow-up 1.5 ± 1.7years. Using multivariate Cox proportional hazard regression models, MCF <25% was highly associated with survival (hazard ratio [HR] 8.5, 95% confidence interval [CI] 4.8-14.9,-P < .0001), which was stronger than the association of EF dichotomized at 50% (HR 2.8, 95% CI 1.8-4.4; P < .0001). MCF <25% remained significantly predictive of survival in a multivariate model that included systolic blood pressure, estimated glomerular filtration rate <65 mL·min^-1·m^-2, New York Heart Association (NYHA) functional class, and health status based on the EuroQol-5D-3L questionnaire (area under the receiver operating characteristic curve [AUC] = 0.83, 95% CI 0.78-0.89).

CONCLUSIONS

MCF was superior to EF in predicting mortality in patients with ATTR. A predictive model combining MCF with systolic blood pressure, renal function, NYHA functional class, and health status was strongly associated with survival in patients with ATTR. CLINICALTRIALS.

GOV IDENTIFIER

NCT00628745.