Effect of myocardial perfusion pattern on frequency and severity of mitral regurgitation in patients with known or suspected coronary artery disease

The Role of the Left Atrium: From Multimodality Imaging to Clinical Practice: A Review

In recent years, new interest is growing in the left atrium (LA). LA functional analysis and measurement have an essential role in cardiac function evaluation. Left atrial size and function are key elements during the noninvasive analysis of diastolic function in several heart diseases. The LA represents a “neuroendocrine organ” with high sensitivity to the nervous, endocrine, and immune systems. New insights highlight the importance of left atrial structural, contractile, and/or electrophysiological changes, introducing the concept of “atrial cardiomyopathy”, which is closely linked to underlying heart disease, arrhythmias, and conditions such as aging. The diagnostic algorithm for atrial cardiomyopathy should follow a stepwise approach, combining risk factors, clinical characteristics, and imaging. Constant advances in imaging techniques offer superb opportunities for a comprehensive evaluation of LA function, underlying specific mechanisms, and patterns of progression. In this literature review, we aim to suggest a practical, stepwise algorithm with integrative multimodality imaging and a clinical approach for LA geometry and functional analysis. This integrates diastolic flow analysis with LA remodelling by the application of traditional and new diagnostic imaging techniques in several clinical settings such as heart failure (HF), atrial fibrillation (AF), coronary artery disease (CAD), and mitral regurgitation (MR).

Myocardial Contractile Mechanics in Ischemic Mitral Regurgitation: Multicenter Data Using Stress Perfusion Cardiovascular Magnetic Resonance

BACKGROUND

Left ventricular (LV) ischemia has been variably associated with functional mitral regurgitation (FMR). Determinants of FMR in patients with ischemia are poorly understood.

OBJECTIVES

This study sought to test whether contractile mechanics in ischemic myocardium underlying the mitral valve have an impact on likelihood of FMR.

METHODS

Vasodilator stress perfusion cardiac magnetic resonance was performed in patients with coronary artery disease (CAD) at multiple centers. FMR severity was confirmed quantitatively via core lab analysis. To test relationship of contractile mechanics with ischemic FMR, regional wall motion and strain were assessed in patients with inducible ischemia and minimal (≤5% LV myocardium, nontransmural) infarction.

RESULTS

A total of 2,647 patients with CAD were studied; 34% had FMR (7% moderate or greater). FMR severity increased with presence (P < 0.001) and extent (P = 0.01) of subpapillary ischemia: patients with moderate or greater FMR had more subpapillary ischemia (odds ratio [OR]: 1.13 per 10% LV; 95% CI: 1.05-1.21; P = 0.001) independent of ischemia in remote regions (P = NS); moderate or greater FMR prevalence increased stepwise with extent of ischemia and infarction in subpapillary myocardium (P < 0.001); stronger associations between FMR and infarction paralleled greater wall motion scores in infarct-affected territories. Among patients with inducible ischemia and minimal infarction (n = 532), wall motion and radial strain analysis showed impaired subpapillary contractile mechanics to associate with moderate or greater FMR (P < 0.05) independent of remote regions (P = NS). Conversely, subpapillary ischemia without contractile dysfunction did not augment FMR likelihood. Mitral and interpapillary dimensions increased with subpapillary radial strain impairment; each remodeling parameter associated with impaired subpapillary strain (P < 0.05) independent of remote strain (P = NS). Subpapillary radial strain (OR: 1.13 per 5% [95% CI: 1.02-1.25]; P = 0.02) and mitral tenting area (OR: 1.05 per 10 mm2 [95% CI: 1.00-1.10]; P = 0.04) were associated with moderate or greater FMR controlling for global remodeling represented by LV end-systolic volume (P = NS): when substituting sphericity for LV volume, moderate or greater FMR remained independently associated with subpapillary radial strain impairment (OR: 1.22 per 5% [95% CI: 1.02-1.47]; P = 0.03).

CONCLUSIONS

Among patients with CAD and ischemia, FMR severity and adverse mitral apparatus remodeling increase in proportion to contractile dysfunction underlying the mitral valve.

Relative Impact of Surgical Mitral Repair and MitraClip on Annular Remodeling-A Potential Mechanism for Therapeutic Response to Mitral Repair for Degenerative Mitral Regurgitation

OBJECTIVES

Three-dimensional transesophageal echocardiography (TEE) is widely used to guide decision-making for mitral repair. The relative impact of surgical mitral valve repair (MVr) and MitraClip on annular remodeling is unknown. The aim was to determine the impact of both mitral repair strategies on annular geometry, including the primary outcome of annular circumference and area.

DESIGN

This was a retrospective observational study of patients who underwent mitral intervention between 2016 and 2020.

SETTING

Weill Cornell Medicine, a single, large, academic medical center.

PARTICIPANTS

The population comprised 50 patients with degenerative mitral regurgitation (MR) undergoing MVr.

INTERVENTIONS

Elective MVr and TEE.

MEASUREMENTS AND MAIN RESULTS

Patients undergoing MitraClip or surgical MVr were matched (1:1) for sex and coronary artery disease. Mitral annular geometry indices were quantified on intraprocedural three-dimensional TEE. Mild or less MR on follow-up transthoracic echocardiography defined optimal response. Patients undergoing MitraClip were older (80 ± eight v 66 ± six years; p < 0.001) but were otherwise similar to surgical patients. Patients undergoing MitraClip had larger baseline left atrial and ventricular sizes, increased tenting height, and volume (p < 0.01), with a trend toward increased annular area (p = 0.23). MitraClip and surgery both induced immediate mitral annular remodeling, including decreased area, circumference, and tenting height (p < 0.001), with greater remodeling with surgical repair. At follow-up (4.1 ± 9.0 months) optimal response (≤ mild MR) was ∼twofold more common with surgery than MitraClip (81% v 46%; p = 0.02). The relative reduction in annular circumference (odds ratio [OR] 1.05 [1.00-1.09] per cm; p = 0.04) and area (OR 1.03 [1.00-1.05] per cm2; p = 0.049) were both associated with optimal response.

CONCLUSIONS

Surgical MVr and MitraClip both reduce annular size, but repair-induced remodeling is greater with surgery and associated with an increased likelihood of optimal response.

Ischemia-Mediated Dysfunction in Subpapillary Myocardium as a Marker of Functional Mitral Regurgitation

OBJECTIVES

The goal of this study was to test whether ischemia-mediated contractile dysfunction underlying the mitral valve affects functional mitral regurgitation (FMR) and the prognostic impact of FMR.

BACKGROUND

FMR results from left ventricular (LV) remodeling, which can stem from myocardial tissue alterations. Stress cardiac magnetic resonance can assess ischemia and infarction in the left ventricle and papillary muscles; relative impact on FMR is uncertain.

METHODS

Vasodilator stress cardiac magnetic resonance was performed in patients with known or suspected coronary artery disease at 7 sites. Images were centrally analyzed for MR etiology/severity, mitral apparatus remodeling, and papillary ischemia.

RESULTS

A total of 8,631 patients (mean age 60.0 ± 14.1 years; 55% male) were studied. FMR was present in 27%, among whom 16% (n = 372) had advanced (moderate or severe) FMR. Patients with ischemia localized to subpapillary regions were more likely to have advanced FMR (p = 0.003); those with ischemia localized to other areas were not (p = 0.17). Ischemic/dysfunctional subpapillary myocardium (odds ratio: 1.24/10% subpapillary myocardium; confidence interval: 1.17 to 1.31; p < 0.001) was associated with advanced FMR controlling for infarction. Among a subgroup with (n = 372) and without (n = 744) advanced FMR matched (1:2) on infarct size/distribution, patients with advanced FMR had increased adverse mitral apparatus remodeling, paralleled by greater ischemic/dysfunctional subpapillary myocardium (p < 0.001). Although posteromedial papillary ischemia was more common with advanced FMR (p = 0.006), subpapillary ischemia with dysfunction remained associated (p < 0.001), adjusting for posteromedial papillary ischemia (p = 0.074). During follow-up (median 5.1 years), 1,473 deaths occurred in the overall cohort; advanced FMR conferred increased mortality risk (hazard ratio: 1.52; 95% confidence interval: 1.25 to 1.86; p < 0.001) controlling for left ventricular ejection fraction, infarction, and ischemia.

CONCLUSIONS

Ischemic and dysfunctional subpapillary myocardium provides a substrate for FMR, which predicts mortality independent of key mechanistic substrates.

Differential myocardial strain in the early postoperative period in patients receiving arterial vs venous bypass grafts: A hypothesis-generating study

OBJECTIVE

Revascularization via coronary artery bypass grafting (CABG) remains a common therapy for coronary artery disease. CABG-based revascularization is most commonly performed via either single arterial graft (SAG) or multiple arterial grafting (MAG) strategies. Echo-derived global and regional longitudinal strain was used to test where SAG or MAG results in immediate differences in left ventricular (LV) function after CABG.

MATERIALS AND METHODS

Pre- and postprocedural intraoperative transesophageal echos were prospectively collected. Two-dimensional LV images were analyzed for global and regional longitudinal strain (GLS), LV ejection fraction, end-diastolic volume, end-systolic volume, and stroke volume (SV).

RESULTS

Twenty patients underwent open, on-pump CABG (63.9 ± 10 years old, 85% male; 10 with SAG and 10 with MAG. Preprocedural GLS significantly differed between patients with SAG and MAG, with patients with MAG having greater GLS (mean [standard deviation, SD], 20.41 [5.54]) than patients with SAG (16.28 [3.48]). After CABG, in patients with MAG, LV strain decreased both globally (-1.13 [3.15]) and regionally in the anterior-lateral (-1.22 [3.84]) and inferior-lateral regions (-1.32 [5.69]), along with LVEF. In patients with SAG, LV strain increased after CABG globally (1.34 [2.73]) and regionally in the anterior-lateral (1.20 [6.49]) and inferior-lateral regions (0.39 [7.26]), as did LVEF and SV. Postprocedure, more patients with MAG were given vasopressor (100% vs 60%) and inotrope infusions (70% vs 40%) than patients with SAG.

CONCLUSIONS

After CABG, LV function quantified through GLS changes both globally and regionally increased after SAG and decreased after MAG. This finding may have important clinical implications in terms of optimizing intraoperative management for patients with CABG and have the potential to guide the improvement of clinical outcomes.

Transcatheter MitraClip repair alters mitral annular geometry - device induced annular remodeling on three-dimensional echocardiography predicts therapeutic response

Background

Echocardiography (echo) is widely used to guide therapeutic decision-making for patients being considered for MitraClip. Relative utility of two- (2D) and three-dimensional (3D) echo predictors of MitraClip response, and impact of MitraClip on mitral annular geometry, are uncertain.

Methods

The study population comprised patients with advanced (> moderate) MR undergoing MitraClip. Mitral annular geometry was quantified on pre-procedural 2D transthoracic echocardiography (TTE) and intra-procedural 3D transesophageal echocardiography (TEE); 3D TEE was used to measure MitraClip induced changes in annular geometry. Optimal MitraClip response was defined as ≤mild MR on follow-up (mean 2.7 ± 2.5 months) post-procedure TTE.

Results

Eighty patients with advanced MR underwent MitraClip; 41% had optimal response (≤mild MR). Responders had smaller pre-procedural global left ventricular (LV) end-diastolic size and mitral annular diameter on 2D TTE (both p ≤ 0.01), paralleling smaller annular area and circumference on 3D TEE (both p = 0.001). Mitral annular size yielded good diagnostic performance for optimal MitraClip response (AUC 0.72, p < 0.01). In multivariate analysis, sub-optimal MitraClip response was independently associated with larger pre-procedural mitral annular area on 3D TEE (OR 1.93 per cm²/m² [CI 1.19–3.13], p = 0.007) and global LV end-diastolic volume on 2D TTE (OR 1.29 per 10 ml/m² [CI 1.02–1.63], p = 0.03). Substitution of 2D TTE derived mitral annular diameter for 3D TEE data demonstrated a lesser association between pre-procedural annular size (OR 5.36 per cm/m² [CI 0.95–30.19], p = 0.06) and sub-optimal MitraClip response. Matched pre- and post-procedural TEE analyses demonstrated MitraClip to acutely decrease mitral annular area and circumference (all p < 0.001) as well as mitral tenting height, area, and volume (all p < 0.05): Magnitude of MitraClip induced reductions in mitral annular circumference on intra-procedural 3D TEE was greater among patients with, compared to those without, sub-optimal MitraClip response (>mild MR) on followup TTE (p = 0.017); greater magnitude of device-induced annular reduction remained associated with sub-optimal MitraClip response even when normalized for pre-procedure annular circumference (p = 0.028).

Conclusions

MitraClip alters mitral annular geometry as quantified by intra-procedural 3D TEE. Pre-procedural mitral annular dilation and magnitude of device-induced reduction in mitral annular size on 3D TEE are each associated with sub-optimal therapeutic response to MitraClip.

Left ventricular geometry predicts optimal response to percutaneous mitral repair via MitraClip: Integrated assessment by two- and three-dimensional echocardiography

OBJECTIVES

To assess impact of left ventricular (LV) chamber remodeling on MitraClip (MClp) response.

BACKGROUND

MitraClip is the sole percutaneous therapy approved for mitral regurgitation (MR) but response varies. LV dilation affects mitral coaptation; determinants of MClp response are uncertain.

METHODS

LV and mitral geometry were quantified on pre- and post-procedure two-dimensional (2D) transthoracic echocardiography (TTE) and intra-procedural three-dimensional (3D) transesophageal echocardiography (TEE). Optimal MClp response was defined as ≤mild MR at early (1-6 month) follow-up.

RESULTS

Sixty-seven degenerative MR patients underwent MClp: Whereas MR decreased ≥1 grade in 94%, 39% of patients had optimal response (≤mild MR). Responders had smaller pre-procedural LV end-diastolic volume (94 ± 24 vs. 109 ± 25 mL/m2 , p = 0.02), paralleling smaller annular diameter (3.1 ± 0.4 vs. 3.5 ± 0.5 cm, p = 0.002), and inter-papillary distance (2.2 ± 0.7 vs. 2.5 ± 0.6 cm, p = 0.04). 3D TEE-derived annular area correlated with 2D TTE (r = 0.59, p < 0.001) and was smaller among optimal responders (12.8 ± 2.1 cm2 vs. 16.8 ± 4.4 cm2 , p = 0.001). Both 2D and 3D mitral annular size yielded good diagnostic performance for optimal MClp response (AUC 0.73-0.84, p < 0.01). In multivariate analysis, sub-optimal MClp response was associated with LV end-diastolic diameter (OR 3.10 per-cm [1.26-7.62], p = 0.01) independent of LA size (1.10 per-cm2 [1.02-1.19], p = 0.01); substitution of mitral annular diameter for LV size yielded an independent association with MClp response (4.06 per-cm2 [1.03-15.96], p = 0.045).

CONCLUSIONS

Among degenerative MR patients undergoing MClp, LV and mitral annular dilation augment risk for residual or recurrent MR, supporting the concept that MClp therapeutic response is linked to sub-valvular remodeling.

Impact of Mitral Regurgitation Severity and Cause on Effort Tolerance-Integrated Stress Myocardial Perfusion Imaging and Echocardiographic Assessment of Patients With Known or Suspected Coronary Artery Disease Undergoing Exercise Treadmill Testing

Background Mitral regurgitation ( MR ) has the potential to impede exercise capacity; it is uncertain whether this is because of regurgitation itself or the underlying cause of valvular insufficiency. Methods and Results The population comprised 3267 patients who underwent exercise treadmill myocardial perfusion imaging and transthoracic echocardiography within 6±8 days. MR was present in 28%, including 176 patients (5%) with moderate or greater MR . Left ventricular systolic function significantly decreased and chamber size increased in relation to MR , paralleling increments in stress and rest myocardial perfusion deficits (all P<0.001). Exercise tolerance (metabolic equivalents of task) decreased stepwise in relation to graded MR severity ( P<0.05). Workload was significantly lower with mild versus no MR (mean±SD, 9.8±3.0 versus 10.1±3.0; P=0.02); magnitude of workload reduction significantly increased among patients with advanced versus those with mild MR (mean±SD, 8.6±3.0 versus 9.8±3.0; P<0.001). MR -associated exercise impairment was accompanied by lower heart rate and blood pressure augmentation and greater dyspnea (all P<0.05). Both functional and nonfunctional MR subgroups demonstrated significantly decreased effort tolerance in relation to MR severity ( P≤0.01); impairment was greater with functional MR ( P=0.04) corresponding to more advanced left ventricular dysfunction and dilation (both P<0.001). Functional MR predicted reduced metabolic equivalent of task-based effort (B=-0.39 [95% CI, -0.62 to -0.17]; P=0.001) independent of MR severity. Among the overall cohort, advanced (moderate or greater) MR was associated with reduced effort tolerance (B=-1.36 [95% CI, -1.80 to -0.93]; P<0.001) and remained significant ( P=0.01) after controlling for age, clinical indexes, stress perfusion defects, and left ventricular dysfunction. Conclusions MR impairs exercise tolerance independent of left ventricular ischemia, dysfunction, and clinical indexes. Magnitude of exercise impairment parallels severity of MR .

Multiplanar strain quantification for assessment of right ventricular dysfunction and non-ischemic fibrosis among patients with ischemic mitral regurgitation

Background

Ischemic mitral regurgitation (iMR) predisposes to right ventricular (RV) pressure and volume overload, providing a nidus for RV dysfunction (RV_DYS) and non-ischemic fibrosis (NIF). Echocardiography (echo) is widely used to assess iMR, but performance of different indices as markers of RV_DYS and NIF is unknown.

Methods

iMR patients prospectively underwent echo and cardiac magnetic resonance (CMR) within 72 hours. Echo quantified iMR, assessed conventional RV indices (TAPSE, RV-S’, fractional area change [FAC]), and strain via speckle tracking in apical 4-chamber (global longitudinal strain [RV-GLS]) and parasternal long axis orientation (transverse strain). CMR volumetrically quantified RVEF, and assessed ischemic pattern myocardial infarction (MI) and septal NIF.

Results

73 iMR patients were studied; 36% had RV_DYS (EF<50%) on CMR among whom LVEF was lower, PA systolic pressure higher, and MI size larger (all p<0.05). CMR RVEF was paralleled by echo results; correlations were highest for RV-GLS (r = 0.73) and lowest for RV-S’ (r = 0.43; all p<0.001). RV_DYS patients more often had CMR-evidenced NIF (54% vs. 7%; p<0.001). Whereas all RV indices were lower among NIF-affected patients (all p≤0.006), percent change was largest for transverse strain (48.3%). CMR RVEF was independently associated with RV-GLS (partial r = 0.57, p<0.001) and transverse strain (r = 0.38, p = 0.002) (R = 0.78, p<0.001). Overall diagnostic performance of RV-GLS and transverse strain were similar (AUC = 0.93[0.87–0.99]|0.91[0.84–0.99], both p<0.001), and yielded near equivalent sensitivity and specificity (85%|83% and 80%|79% respectively).

Conclusion

Compared to conventional echo indices, RV strain parameters yield stronger correlation with CMR-defined RVEF and potentially constitute better markers of CMR-evidenced NIF in iMR.

Right Ventricular Dysfunction Impairs Effort Tolerance Independent of Left Ventricular Function Among Patients Undergoing Exercise Stress Myocardial Perfusion Imaging

BACKGROUND

Right ventricular (RV) and left ventricular (LV) function are closely linked due to a variety of factors, including common coronary blood supply. Altered LV perfusion holds the potential to affect the RV, but links between LV ischemia and RV performance, and independent impact of RV dysfunction on effort tolerance, are unknown.

METHODS AND RESULTS

The population comprised 2051 patients who underwent exercise stress myocardial perfusion imaging and echo (5.5±7.9 days), among whom 6% had echo-evidenced RV dysfunction. Global summed stress scores were ≈3-fold higher among patients with RV dysfunction, attributable to increments in inducible and fixed LV perfusion defects (all P≤0.001). Regional inferior and lateral wall ischemia was greater among patients with RV dysfunction (both P<0.01), without difference in corresponding anterior defects (P=0.13). In multivariable analysis, inducible inferior and lateral wall perfusion defects increased the likelihood of RV dysfunction (both P<0.05) independent of LV function, fixed perfusion defects, and pulmonary artery pressure. Patients with RV dysfunction demonstrated lesser effort tolerance whether measured by exercise duration (6.7±2.8 versus 7.9±2.9 minutes; P<0.001) or peak treadmill stage (2.6±0.9 versus 3.1±1.0; P<0.001), paralleling results among patients with LV dysfunction (7.0±2.9 versus 8.0±2.9; P<0.001|2.7±1.0 versus 3.1±1.0; P<0.001 respectively). Exercise time decreased stepwise in relation to both RV and LV dysfunction (P<0.001) and was associated with each parameter independent of age or medication regimen.

CONCLUSIONS

Among patients with known or suspected coronary artery disease, regional LV ischemia involving the inferior and lateral walls confers increased likelihood of RV dysfunction. RV dysfunction impairs exercise tolerance independent of LV dysfunction.

Myocardial perfusion pattern for stratification of ischemic mitral regurgitation response to percutaneous coronary intervention

OBJECTIVE

Ischemic mitral regurgitation (MR) is common, but its response to percutaneous coronary intervention (PCI) is poorly understood. This study tested the utility of myocardial perfusion imaging (MPI) for the stratification of MR response to PCI.

METHODS

MPI and transthoracic echocardiography (echo) were performed among patients undergoing PCI. MPI was used to assess stress/rest myocardial perfusion. MR was assessed via echo (performed before and after PCI).

RESULTS

A total of 317 patients with abnormal myocardial perfusion on MPI underwent echo 25±39 days before PCI. MR was present in 52%, among whom 24% had advanced (≥moderate) MR. MR was found to be associated with left ventricular (LV) chamber dilation on MPI and echo (both P<0.001). The magnitude of global LV perfusion deficits increased in relation to MR severity (P<0.01). Perfusion differences were greatest for global summed rest scores, which were 1.6-fold higher among patients with advanced MR versus those with mild MR (P=0.004), and 2.4-fold higher versus those without MR (P<0.001). In multivariate analysis, advanced MR was found to be associated with a fixed perfusion defect size on MPI [odds ratio 1.16 per segment (confidence interval 1.002-1.34), P=0.046], independent of LV volume [odds ratio 1.10 per 10 ml (confidence interval 1.04-1.17), P=0.002]. Follow-up via echo (1.0±0.6 years) demonstrated MR to decrease (≥1 grade) in 31% of patients and increase in 12% of patients. Patients with increased MR after PCI had more severe inferior perfusion defects on baseline MPI (P=0.028), whereas defects in other distributions and LV volumes were similar (P=NS).

CONCLUSION

The extent and distribution of single-photon emission computed tomography-evidenced myocardial perfusion defects impact MR response to revascularization. An increased magnitude of inferior fixed perfusion defects predicts post-PCI progression of MR.

Mitral valve disease--morphology and mechanisms

Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.