Impact of contrast echocardiography on accurate discrimination of specific degree of left ventricular systolic dysfunction and comparison with cardiac magnetic resonance imaging.

AIM: Limited data exist on the impact of contrast-enhanced echocardiography on treatment decisions in heart failure patients that require specific left ventricular ejection fraction (LVEF) criteria. This study assessed accuracy of contrast-enhanced echocardiography in identifying patients with LVEF >35% vs ≤35% with cardiac magnetic resonance (CMR) used as reference method. METHODS AND RESULTS: Fifty-five patients from prospective Alberta HEART cohort with LVEF ≤50% on CMR were included. All patients had echocardiography performed within 2 weeks of CMR. Contrast agent was used when ≥2 contiguous LV endocardial segments were poorly visualized on echocardiography. LVEF was computed by Simpson's biplane method using non-contrast echocardiography and contrast-enhanced echocardiography and by outlining the endocardial contours in short-axis cine CMR images. Strong agreement in LV volumes and LVEF was seen between CMR and echocardiography with and without contrast (intra-class correlation coefficients >0.8) with less underestimation of LV volumes by contrast-enhanced echocardiography. Good agreement in LVEF ≤35% vs >35% was seen between CMR and non-contrast echocardiography with optimal images (κ 0.862) and contrast echocardiography (κ 0.769) while it was moderate for non-contrast echocardiography with suboptimal images (κ 0.491). The use of LV contrast in patients with suboptimal images (n = 39) resulted in correctly upgrading LVEF from ≤35% to >35% in 5 (13%) patients and downgrading LVEF from >35% to ≤35% in 2 (5%) patients using CMR as reference. CONCLUSIONS: Contrast-enhanced echocardiography in heart failure patients with suboptimal images helps to more accurately assess eligibility for specific therapies and avoid need for further testing, therefore should be considered routine part of echocardiographic assessment.

Resolution of Cardiac Infiltration Following Autologous Stem Cell Transplantation for AL Amyloidosis.

A 43-year-old man presented with severe heart failure secondary to high-risk light chain cardiac amyloidosis. He underwent chemotherapy and autologous stem cell transplantation with complete hematologic response. Serial cardiac magnetic resonance imaging post-transplant demonstrated gradual normalization of biventricular function and myocardial T1, a surrogate measure of disease burden.

The paradox of left ventricular assist device unloading and myocardial recovery in end-stage dilated cardiomyopathy: implications for heart failure in the elderly.

Dilated cardiomyopathy (DCM) is a common debilitating condition with limited therapeutic options besides heart transplantation or palliation. It is characterized by maladaptive remodeling of cardiomyocytes, extracellular collagen matrix (ECCM) and left ventricular (LV) geometry which contributes to further dysfunction. LV assist devices (LVADs) can reverse adverse remodeling in end-stage DCM. However, there is a disconnect between the benefits of prolonged unloading with LVAD at molecular and cellular levels and the low rate of bridge to recovery (BTR). Potential explanations for this paradox include insufficient reverse ECCM remodeling and/or excessive reverse cardiomyocyte remodeling with atrophy. LVAD therapy is associated with decreased collagen turnover and cross-linking and increased tissue angiotensin II (AngII), whereas LVAD combined with angiotensin-converting enzyme inhibition results in decreased tissue AngII and collagen cross-linking, normalizes LV end-diastolic pressure volume relationships and is associated with modestly higher rates of BTR. Much remains to be learned about ventricular reverse remodeling after LVAD. This can be facilitated through systematic collection and comparison of recovered and unrecovered myocardium. Importantly, vigilant monitoring for ventricular recovery among LVAD patients is needed, particularly in older patients receiving LVAD for destination therapy. In addition, prospective multicenter trials are needed to clarify the potential benefit of concomitant heart failure therapy with selective ß2 agonism on ventricular recovery.

Mechanical circulatory support for elderly heart failure patients.

End-stage systolic heart failure is an increasingly common problem in elderly patients and is associated with high cost, poor quality of life, and poor outcomes. Mechanical circulatory support is a promising therapy as both a bridge to transplantation and destination therapy. Elderly patients are frequently ineligible for heart transplantation because of their age and comorbidities, and the application of mechanical circulatory support for destination therapy in this population is not well defined. A review of the literature was undertaken to better characterize our experience to date with mechanical circulatory support in older heart failure populations. Mechanical circulatory support is being employed increasingly for destination therapy indications in older patients. The newer continuous flow devices appear to have disproportionate advantage in elderly patients, which has translated into marked improvement in 1- and 2-year survival. The rational implementation of MCS devices in elderly heart failure patients needs to focus on (1) continuous flow devices that appear to have particular benefit in this population, (2) extensive pre-MCS assessment including variables relating to frailty, and (3) intervening before these patients develop cardiogenic shock. More data are needed on the cost-benefit analysis of routine use of CF devices as destination therapy in elderly patients with heart failure.

2021 Update on Safety of Magnetic Resonance Imaging: Joint Statement From Canadian Cardiovascular Society/Canadian Society for Cardiovascular Magnetic Resonance/Canadian Heart Rhythm Society.

Magnetic resonance imaging (MRI) is often considered the gold-standard test for characterizing cardiac as well as noncardiac structure and function. However, many patients with cardiac implantable electronic devices (CIEDs) and/or severe renal dysfunction are unable to undergo this test because of safety concerns. In the past 10 years, newer-generation CIEDs and gadolinium-based contrast agents (GBCAs) as well as coordinated care between imaging and heart rhythm device teams have mitigated risk to patients and improved access to MRI at many hospitals. The purpose of this statement is to review published data on safety of MRI in patients with conditional and nonconditional CIEDs in addition to patient risks from older and newer GBCAs. This statement was developed through multidisciplinary collaboration of pan-Canadian experts after a relevant and independent literature search by the Canadian Agency for Drugs and Technologies in Health. All recommendations align with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Key recommendations include: (1) the development of standardized protocols for patients with a CIED undergoing MRI; (2) patients with MRI nonconditional pacemakers and pacemaker dependency should be programmed to asynchronous mode and those with MRI nonconditional transvenous defibrillators should have tachycardia therapies turned off during the scan; and (3) macrocyclic or newer linear GBCAs should be used in preference to older GBCAs because of their better safety profile in patients at higher risk of nephrogenic systemic fibrosis.

Cardiovascular magnetic resonance in the diagnosis of acute heart transplant rejection: a review.

BACKGROUND: Screening for organ rejection is a critical component of care for patients who have undergone heart transplantation. Endomyocardial biopsy is the gold standard screening tool, but non-invasive alternatives are needed. Cardiovascular magnetic resonance (CMR) is well suited to provide an alternative to biopsy because of its ability to quantify ventricular function, morphology, and characterize myocardial tissue. CMR is not widely used to screen for heart transplant rejection, despite many trials supporting its use for this indication. This review summarizes the different CMR sequences that can detect heart transplant rejection as well as the strengths and weaknesses of their application. RESULTS: T2 quantification by spin echo techniques has been criticized for poor reproducibility, but multiple studies show its utility in screening for rejection. Human and animal data estimate that T2 quantification can diagnose rejection with sensitivities and specificities near 90%. There is also a suggestion that T2 quantification can predict rejection episodes in patients with normal endomyocardial biopsies.T1 quantification has also shown association with biopsy proven rejection in a small number of trials. T1 weighted gadolinium early enhancement appeared promising in animal data, but has had conflicting results in human trials. Late gadolinium enhancement in the diagnosis of rejection has not been evaluated.CMR derived measures of ventricular morphology and systolic function have insufficient sensitivity to diagnose mild to moderate rejection. CMR derived diastolic function can demonstrate abnormalities in allografts compared to native human hearts, but its ability to diagnose rejection has not yet been tested.There is promising animal data on the ability of iron oxide contrast agents to illustrate the changes in vascular permeability and macrophage accumulation seen in rejection. Despite good safety data, these contrast agents have not been tested in the human heart transplant population. CONCLUSION: T2 quantification has demonstrated the best correlation to biopsy proven heart transplant rejection. Further studies evaluating diastolic function, late gadolinium enhancement, and iron oxide contrast agents to diagnose rejection are needed. Future studies should focus on combining multiple CMR measures into a transplant rejection scoring system which would improve sensitivity and possibly reduce, if not eliminate, the need for endomyocardial biopsy.

Variables Associated With Cardiac Surgical Waitlist Mortality From a Population-Based Cohort.

BACKGROUND: Cardiac surgery waitlist recommendations, which were developed based on expert opinion, poorly predict preoperative mortality. Studies reporting risk factors for waitlist mortality have not evaluated the risks including nonadherence to waitlist benchmarks. METHODS: In patients who underwent cardiac surgery or died on the waitlist between 2005 and 2015, we used a Fine and Gray competing risk model to identify independent predictors of waitlist mortality in 12,106 patients scheduled for urgent, semiurgent, or nonurgent surgery. The predictive variables were compared with Canadian Cardiovascular Society (CCS) waitlist recommendations using the Akaike information criterion. RESULTS: A total of 101 (0.8%) patients died awaiting surgery. The median wait times and frequency waitlist deaths among emergent, urgent, semi-urgent, and nonurgent surgery were 0.6, 7.4, 69.0, 55.5 days (P < 0.001) and 6.3%, 0.8%, 0.3%, 0.6% (P < 0.001), respectively. Adherence to CCS waitlist recommendations was higher in patients who died on the waitlist (51.6% vs 70.8%, P = 0.001) and was not predictive of waitlist mortality (hazard ratio 1.48, 95% confidence interval 0.62-0.56). Independent predictors of waitlist mortality were age, aortic surgery, ejection fraction < 35%, urgent surgery, prior myocardial infarction, haemodynamic instability during cardiac catheterization, hypertension, and dyslipidemia. These variables were superior to current CCS guidelines (Akaike information criterion 1251 vs 1317, likelihood ratio test P < 0.001). CONCLUSIONS: CCS waitlist recommendations were poorly predictive of waitlist mortality and the majority of waitlist deaths occur within recommended benchmarks. We identified variables associated with waitlist mortality with improved clinical performance. Our findings suggest a need to re-evaluate cardiac surgical triage criteria using evidence-based data.

Transcatheter Valve-in-Valve: A Cautionary Tale.

Transcatheter aortic valve replacement (TAVR) by valve-in-valve (VIV) implantation is an alternative treatment for high-risk patients with a degenerating aortic bioprosthesis. We present a case of transapical TAVR VIV with a 29-mm Edwards SAPIEN XT (ESV) (Edwards Lifesciences, Irvine, CA) into a 29-mm Medtronic Freestyle stentless bioprosthesis (Medtronic Inc, Minneapolis, MN) in which unanticipated dilatation of the Freestyle bioprosthesis resulted in intraprocedural embolization of the TAVR valve, necessitating urgent conversion to a conventional surgical aortic valve replacement (AVR). Our experience suggests that TAVR VIV with the 29-mm ESV in the setting of a degenerated 29-mm Freestyle stentless bioprosthesis must be undertaken with caution.

Correlation of cardiovascular magnetic resonance imaging findings and endomyocardial biopsy results in patients undergoing screening for heart transplant rejection.

BACKGROUND: Endomyocardial biopsy (EMB) is the current gold standard to screen for heart transplant rejection but has important risks and limitations. Cardiovascular magnetic resonance imaging (CMRI) is increasingly used to characterize cardiac function and myocardial tissue. We evaluated the diagnostic accuracy of CMRI compared with EMB and clinically diagnosed heart transplant rejection. METHODS: Comprehensive CMRI scans were performed on adult heart transplant recipients within 24 hours of EMB (routine or clinically indicated), before initiation of any anti-rejection therapy, and blinded to EMB results. Multivariable analysis was used to create CMRI diagnostic criteria for comparison with a positive EMB (Grade ≥ 2R or antibody-mediated rejection) and clinical rejection (change in medical therapy to treat rejection). RESULTS: Sixty participants (75% male; mean age, 51 ± 14 years) were recruited, providing 73 comparisons between CMRI and EMB for the diagnosis of rejection. Multivariable logistic regression identified myocardial edema (T2 relaxation time) and right ventricular end-diastolic volume index as independent predictors of a positive EMB. Combining threshold right ventricular end-diastolic volume index and edema values predicted a positive EMB with very good accuracy: sensitivity, 93%; specificity, 78%; positive predictive value, 52%; and negative predictive valve, 98%. CMRI was more sensitive than EMB at predicting clinical rejection (sensitivity of 67% vs 58%). CONCLUSIONS: CMRI has high sensitivity and high negative predictive value in predicting biopsy-positive heart transplant rejection and may be useful as a screening test before routine EMB. CMRI also has better sensitivity for clinically diagnosed heart transplant rejection and could be helpful in cases of negative rejection on the biopsy specimen.

Late gadolinium enhancement in cardiac transplant patients is associated with adverse ventricular functional parameters and clinical outcomes.

BACKGROUND: Heart transplant recipients (HTRs) experience multiple cardiac complications, many of which might produce myocardial fibrosis. Cardiovascular magnetic resonance imaging (CMR) can image myocardial fibrosis using late gadolinium enhancement (LGE) imaging. We hypothesized that the presence and volume of LGE in heart transplant recipients correlates with left ventricular (LV) functional parameters and clinical outcomes. METHODS: Thirty-eight stable HTRs underwent a CMR study and clinical follow-up. RESULTS: In 38 stable HTRs, LGE was seen in 19 patients (50%), of which 15 (79%) had a nonischemic pattern and 4 (21%) had an ischemic pattern. LGE volume was associated with reduced LV ejection fraction (EF) (R(2) = 0.57; P = 0.001) and increased LV end-diastolic volume (R(2) = 0.59; P = 0.001). The presence of LGE was associated with cardiovascular death or hospitalization within the next year (P = 0.04), and patients who died or were hospitalized had more LGE than those that were not hospitalized (15 g vs 7 g; P = 0.03). CONCLUSIONS: LGE is common in HTR and is associated with adverse ventricular remodelling and adverse clinical outcomes. LGE might be a useful noninvasive approach to monitor graft disease in asymptomatic patients after heart transplant.