Invited Commentary

Abstract

Diastolic dysfunction refers to aberrant diastolic distensibility, filling, or relaxation of the left ventricle, regardless of whether the ejection fraction is normal or abnormal, asymptomatic, or symptomatic [1Gaasch W.H. Zile M.R. Left ventricular diastolic dysfunction and diastolic heart failure.Annu Rev Med. 2004; 55: 373-394Crossref PubMed Scopus (227) Google Scholar]. Population-based studies have shown that approximately a third of heart failure patients have normal or near-normal ejection fraction [2Redfield M.M. Jacobsen S.J. Burnett J.C. Mahoney D.W. Bailey K.R. Rodeheffer R.J. Burden of systolic and diastolic ventricular dysfunction in the community: appreciating the scope of the heart failure epidemic.JAMA. 2003; 289: 194-202Crossref PubMed Scopus (2456) Google Scholar]. The prevalence of diastolic heart failure is highest among the hypertensive, diabetic, interstitial cardiomyopathies especially ventricular hypertrophy, as well as those in the seventh decade of life or older [1Gaasch W.H. Zile M.R. Left ventricular diastolic dysfunction and diastolic heart failure.Annu Rev Med. 2004; 55: 373-394Crossref PubMed Scopus (227) Google Scholar]. There is epidemiologic evidence that survival improved among patients with reduced ejection fraction, whereas it did not improve among patients with preserved ejection fraction.Although the exact pathologic process for diastolic dysfunction is unknown, inflammatory cytokines, osteopontin, and the fibroblast have been proposed. Despite these findings, diastolic dysfunction in the surgical arena remains somewhat elusive due to (1) the lack of one true definition (mitral valve inflow pulse wave Doppler, pulmonary vein flow Doppler, and mitral annular tissue Doppler velocities, which are usually septal and lateral annular velocities) and (2) the difficulty in objectively assessing efficacy of available therapies. The presence of diastolic dysfunction can alert the patient's physician and surgeon of potential suboptimal ventricle performance. However, what does this really mean prior to revascularization of an ischemic myocardium?The excellent article by Swaminathan and colleagues [3Swaminathan M. Nicoara A. Phillips-Bute B.G. et al.Utility of a simple algorithm to grade diastolic dysfunction and predict outcome after coronary artery bypass graft surgery.Ann Thorac Surg. 2011; 91: 1844-1851Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar] in this issue of The Annals of Thoracic Surgery used a simplified and modified algorithm to assign diastolic dysfunction grade in the operating room with transesophageal echocardiography. This group elegantly illustrated sound correlation of diastolic grade and long-term risk of major adverse cardiac events. In physiologic terms, the ventricular wall tension is increased, placing more risk on the perfusion-sensitive subendocardium of an already ischemic heart. Furthermore, limitation of coronary perfusion, in the face of the critical perioperative period, and suboptimal revascularization can provide a substrate for hemodynamic compromise and overt ventricular failure. This may further explain the finding of greater loss of life with greater degree of diastolic dysfunction up to many years in the cohort. Hemodynamic loading and heart rate need to be defined before quantitatively grading diastolic dysfunction in the operating room. Unanswered in this study, but what should be investigated relates to the influence of the long-term effect of total revascularization versus subtotal revascularization on diastolic function recovery (ie, increased bypass target sites). Furthermore, left ventricular diastolic function may be an important predictor variable of long-term rhythm outcome if intraoperative ablation of atrial fibrillation is performed during revascularization. So is there anything more we can do at this stage with these timely findings?There is now enough evidence to initiate quality improvement research to study ventricular stiffness in coronary artery bypass surgery. Current therapies including β-blockers, as well as angiotensin-converting enzyme inhibitors or antagonists can be helpful. Furthermore, although diastolic dysfunction does not yet belong to outcome predictor scores, such as The Society of Thoracic Surgeon's (STS) score or the European System for Cardiac Operative Risk Evaluation (EuroSCORE), we should start engaging the use of it during our active informed consent process with the patient prior to surgery. Diastolic dysfunction refers to aberrant diastolic distensibility, filling, or relaxation of the left ventricle, regardless of whether the ejection fraction is normal or abnormal, asymptomatic, or symptomatic [1Gaasch W.H. Zile M.R. Left ventricular diastolic dysfunction and diastolic heart failure.Annu Rev Med. 2004; 55: 373-394Crossref PubMed Scopus (227) Google Scholar]. Population-based studies have shown that approximately a third of heart failure patients have normal or near-normal ejection fraction [2Redfield M.M. Jacobsen S.J. Burnett J.C. Mahoney D.W. Bailey K.R. Rodeheffer R.J. Burden of systolic and diastolic ventricular dysfunction in the community: appreciating the scope of the heart failure epidemic.JAMA. 2003; 289: 194-202Crossref PubMed Scopus (2456) Google Scholar]. The prevalence of diastolic heart failure is highest among the hypertensive, diabetic, interstitial cardiomyopathies especially ventricular hypertrophy, as well as those in the seventh decade of life or older [1Gaasch W.H. Zile M.R. Left ventricular diastolic dysfunction and diastolic heart failure.Annu Rev Med. 2004; 55: 373-394Crossref PubMed Scopus (227) Google Scholar]. There is epidemiologic evidence that survival improved among patients with reduced ejection fraction, whereas it did not improve among patients with preserved ejection fraction. Although the exact pathologic process for diastolic dysfunction is unknown, inflammatory cytokines, osteopontin, and the fibroblast have been proposed. Despite these findings, diastolic dysfunction in the surgical arena remains somewhat elusive due to (1) the lack of one true definition (mitral valve inflow pulse wave Doppler, pulmonary vein flow Doppler, and mitral annular tissue Doppler velocities, which are usually septal and lateral annular velocities) and (2) the difficulty in objectively assessing efficacy of available therapies. The presence of diastolic dysfunction can alert the patient's physician and surgeon of potential suboptimal ventricle performance. However, what does this really mean prior to revascularization of an ischemic myocardium? The excellent article by Swaminathan and colleagues [3Swaminathan M. Nicoara A. Phillips-Bute B.G. et al.Utility of a simple algorithm to grade diastolic dysfunction and predict outcome after coronary artery bypass graft surgery.Ann Thorac Surg. 2011; 91: 1844-1851Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar] in this issue of The Annals of Thoracic Surgery used a simplified and modified algorithm to assign diastolic dysfunction grade in the operating room with transesophageal echocardiography. This group elegantly illustrated sound correlation of diastolic grade and long-term risk of major adverse cardiac events. In physiologic terms, the ventricular wall tension is increased, placing more risk on the perfusion-sensitive subendocardium of an already ischemic heart. Furthermore, limitation of coronary perfusion, in the face of the critical perioperative period, and suboptimal revascularization can provide a substrate for hemodynamic compromise and overt ventricular failure. This may further explain the finding of greater loss of life with greater degree of diastolic dysfunction up to many years in the cohort. Hemodynamic loading and heart rate need to be defined before quantitatively grading diastolic dysfunction in the operating room. Unanswered in this study, but what should be investigated relates to the influence of the long-term effect of total revascularization versus subtotal revascularization on diastolic function recovery (ie, increased bypass target sites). Furthermore, left ventricular diastolic function may be an important predictor variable of long-term rhythm outcome if intraoperative ablation of atrial fibrillation is performed during revascularization. So is there anything more we can do at this stage with these timely findings? There is now enough evidence to initiate quality improvement research to study ventricular stiffness in coronary artery bypass surgery. Current therapies including β-blockers, as well as angiotensin-converting enzyme inhibitors or antagonists can be helpful. Furthermore, although diastolic dysfunction does not yet belong to outcome predictor scores, such as The Society of Thoracic Surgeon's (STS) score or the European System for Cardiac Operative Risk Evaluation (EuroSCORE), we should start engaging the use of it during our active informed consent process with the patient prior to surgery. Utility of a Simple Algorithm to Grade Diastolic Dysfunction and Predict Outcome After Coronary Artery Bypass Graft SurgeryThe Annals of Thoracic SurgeryVol. 91Issue 6PreviewInclusion of a measure of left ventricular diastolic dysfunction (LVDD) may improve risk prediction after cardiac surgery. Current LVDD grading guidelines rely on echocardiographic variables that are not always available or aligned to allow grading. We hypothesized that a simplified algorithm involving fewer variables would enable more patients to be assigned a LVDD grade compared with a comprehensive algorithm, and also be valid in identifying patients at risk of long-term major adverse cardiac events (MACE). Full-Text PDF