Catheterization and Cardiovascular Interventions 84:321–322 (2014)
Editorial Comment The Impact of Left Anterior Descending Coronary Artery Length on Survival Following Myocardial Infarction: To the Apex and Beyond Morgan H. Randall, BS, and David J. Moliterno,* MD Division of Cardiovascular Medicine, Gill Heart Institute, University of Kentucky, Lexington, Kentucky
Numerous predictors for outcome following myocardial infarction (MI) have been established. These can be categorically divided in many different ways, such as variables which are patient-related (e.g., diabetes mellitus) versus system-related (e.g., door-to-balloon time). Other broad ways to categorize outcome predictors include those factors which are fixed (e.g., age) versus modifiable (e.g., LDL-cholesterol). From a myocardium-specific standpoint, categories are generally based on anatomy (e.g., MI location) or physiology (e.g., left ventricular ejection fraction). In addition are those factors which are evaluable at unique times in the patient’s course. For example, there are factors assessed at presentation (e.g., heart rate) versus those which need to be considered during hospitalization (e.g., creatine phosphokinase [CPK] levels) and during long-term follow-up (e.g., implantable defibrillators). Finally, it is important to remember that while each of these has been shown to have independent predictive value, this value is limited by the information and events known at that time. Among the largest prospective studies to assess baseline predictors for mortality following ST-elevation MI (STEMI) came from the thrombolytic therapy era. In the Global Use of Strategies to Open Occluded Coronary Arteries trial, 41,021 patients were randomized to different thrombolytic therapy strategies, and multivariable modeling was used to assess the predictive value of characteristics for 30-day mortality. Interestingly, five variables together—age, systolic blood pressure, Killip Class, heart rate, and MI location— provided roughly 90% of the prognostic information [1]. Age alone accounted for approximately 30% of the prognostic information, while factors associated with C 2014 Wiley Periodicals, Inc. V
hemodynamic status/ventricular performance (i.e., systolic blood pressure, Killip Class, and heart rate) accounted for over 50%. The final factor of this group, MI location, accounted for 5% of the prognostic information. It was identified from the electrocardiogram; anterior wall infarction predicted a worse outcome versus other territories. Once hospitalized, outcome predictors following STEMI become more focused as the extent of myocardium at risk and the amount salvaged can be measured. Simple metrics can be used such as CPK area under the curve (values integrated over time) or left ventricular ejection fraction by echocardiography. More sophisticated measures, such as the percentage of myocardium infarcted as calculated by magnetic resonance imaging, have more recently become available. In the catheterization laboratory, the location of coronary artery occlusion, rate of antegrade coronary flow following reperfusion, and grade of final myocardial blush have been shown to be reliable prognosticators. These various parameters can be used to predict resultant left ventricular performance and subsequent mortality rates. Indeed, a very large MI is a leading predictor and cause of early death and can manifest acutely as cardiogenic shock. While shock is relatively infrequent (5–8% of STEMI cases), its associated mortality is very high (40–60%). A majority of patients developing shock in the setting of STEMI have an anterior wall MI as a result of an occlusion of the left anterior descending (LAD) coronary artery. Shock can occur with occlusion of any of the epicardial coronary arteries, though intuitively does so more often with proximal occlusions of the LAD, since it provides blood to the largest amount of left ventricular mass. In this issue of Catheterization and Cardiovascular Interventions, Ilia et al. [2] assessed the prognostic Conflict of interest: Nothing to report. *Correspondence to: David J. Moliterno, MD, Department of Internal Medicine, University of Kentucky, 900 S. Limestone Avenue, 329 Wethington Building, Lexington, KY 40536-0200. E-mail: [email protected] Received 30 May 2014; Revision accepted 31 May 2014 DOI: 10.1002/ccd.25554 Published online 21 July (wileyonlinelibrary.com)
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value of the length of the LAD among patients undergoing primary percutaneous coronary intervention (PCI) for occlusions of the proximal LAD. Among 196 such patients from a 10-year interval (7% of all patients undergoing primary PCI), 57% were found to have an LAD that wrapped around the left ventricular apex, and the remainder had an LAD which terminated at or before the apex. Considering these two groups and available baseline and in-hospital characteristics, Ilia et al. found LAD length to be the strongest predictor of death with multivariate analysis. At 1 year, mortality for those with a wraparound LAD was 14% versus 1% for those with a shorter vessel. These observations are interesting and generally make sense—a greater area of myocardium at risk portends a higher mortality rate. While the length of coronary arteries is more continuous than dichotomous, this simple categorization of the LAD is helpful. It would be interesting in a larger study with robust statistical power and including prospective and ongoing collection of data to refine the hazard ratio for mortality with a wraparound LAD versus a shorter vessel. Since the present study had a relatively small cohort, important and well-established factors known to predict and
affect mortality, such as age, Killip Class, myocardial blush score, and left ventricular function, were not found to be different between the two groups and were not predictive of subsequent mortality over many years. Another challenge with retrospective or isolated assessments in time is the absence of information regarding subsequent care or events. Fortunately, cardiovascular medicine has numerous effective therapies for STEMI treatment, such as aspirin, statins, betablockers, angiotensin converting enzyme inhibitors, cardiac rehabilitation, and internal defibrillators, to name but a few, and each of these clearly impacts mortality rates. REFERENCES 1. Lee KL, Woodlief LH, Topol EJ, Weaver WD, Betriu A, Col J, Simoons M, Aylward P, Van de Werf F, Califf RM. Predictors of 30-day mortality in the era of reperfusion for acute myocardial infarction. Results from an international trial of 41,021 patients. GUSTO-I Investigators. Circulation 1995;91:1659–1668. 2. Ilia R, Weinstein JM, Wolak A, Gilutz, Cafri C. Length of left anterior descending coronary artery determines prognosis in acute anterior wall myocardial infarction. Cathet Cardiovasc Interv 2014;84:316–320.
Catheterization and Cardiovascular Interventions DOI 10.1002/ccd. Published on behalf of The Society for Cardiovascular Angiography and Interventions (SCAI).
Editorial Comment The Impact of Left Anterior Descending Coronary Artery Length on Survival Following Myocardial Infarction: To the Apex and Beyond Morgan H. Randall, BS, and David J. Moliterno,* MD Division of Cardiovascular Medicine, Gill Heart Institute, University of Kentucky, Lexington, Kentucky
Numerous predictors for outcome following myocardial infarction (MI) have been established. These can be categorically divided in many different ways, such as variables which are patient-related (e.g., diabetes mellitus) versus system-related (e.g., door-to-balloon time). Other broad ways to categorize outcome predictors include those factors which are fixed (e.g., age) versus modifiable (e.g., LDL-cholesterol). From a myocardium-specific standpoint, categories are generally based on anatomy (e.g., MI location) or physiology (e.g., left ventricular ejection fraction). In addition are those factors which are evaluable at unique times in the patient’s course. For example, there are factors assessed at presentation (e.g., heart rate) versus those which need to be considered during hospitalization (e.g., creatine phosphokinase [CPK] levels) and during long-term follow-up (e.g., implantable defibrillators). Finally, it is important to remember that while each of these has been shown to have independent predictive value, this value is limited by the information and events known at that time. Among the largest prospective studies to assess baseline predictors for mortality following ST-elevation MI (STEMI) came from the thrombolytic therapy era. In the Global Use of Strategies to Open Occluded Coronary Arteries trial, 41,021 patients were randomized to different thrombolytic therapy strategies, and multivariable modeling was used to assess the predictive value of characteristics for 30-day mortality. Interestingly, five variables together—age, systolic blood pressure, Killip Class, heart rate, and MI location— provided roughly 90% of the prognostic information [1]. Age alone accounted for approximately 30% of the prognostic information, while factors associated with C 2014 Wiley Periodicals, Inc. V
hemodynamic status/ventricular performance (i.e., systolic blood pressure, Killip Class, and heart rate) accounted for over 50%. The final factor of this group, MI location, accounted for 5% of the prognostic information. It was identified from the electrocardiogram; anterior wall infarction predicted a worse outcome versus other territories. Once hospitalized, outcome predictors following STEMI become more focused as the extent of myocardium at risk and the amount salvaged can be measured. Simple metrics can be used such as CPK area under the curve (values integrated over time) or left ventricular ejection fraction by echocardiography. More sophisticated measures, such as the percentage of myocardium infarcted as calculated by magnetic resonance imaging, have more recently become available. In the catheterization laboratory, the location of coronary artery occlusion, rate of antegrade coronary flow following reperfusion, and grade of final myocardial blush have been shown to be reliable prognosticators. These various parameters can be used to predict resultant left ventricular performance and subsequent mortality rates. Indeed, a very large MI is a leading predictor and cause of early death and can manifest acutely as cardiogenic shock. While shock is relatively infrequent (5–8% of STEMI cases), its associated mortality is very high (40–60%). A majority of patients developing shock in the setting of STEMI have an anterior wall MI as a result of an occlusion of the left anterior descending (LAD) coronary artery. Shock can occur with occlusion of any of the epicardial coronary arteries, though intuitively does so more often with proximal occlusions of the LAD, since it provides blood to the largest amount of left ventricular mass. In this issue of Catheterization and Cardiovascular Interventions, Ilia et al. [2] assessed the prognostic Conflict of interest: Nothing to report. *Correspondence to: David J. Moliterno, MD, Department of Internal Medicine, University of Kentucky, 900 S. Limestone Avenue, 329 Wethington Building, Lexington, KY 40536-0200. E-mail: [email protected] Received 30 May 2014; Revision accepted 31 May 2014 DOI: 10.1002/ccd.25554 Published online 21 July (wileyonlinelibrary.com)
2014
in
Wiley
Online
Library
322
Randall and Moliterno
value of the length of the LAD among patients undergoing primary percutaneous coronary intervention (PCI) for occlusions of the proximal LAD. Among 196 such patients from a 10-year interval (7% of all patients undergoing primary PCI), 57% were found to have an LAD that wrapped around the left ventricular apex, and the remainder had an LAD which terminated at or before the apex. Considering these two groups and available baseline and in-hospital characteristics, Ilia et al. found LAD length to be the strongest predictor of death with multivariate analysis. At 1 year, mortality for those with a wraparound LAD was 14% versus 1% for those with a shorter vessel. These observations are interesting and generally make sense—a greater area of myocardium at risk portends a higher mortality rate. While the length of coronary arteries is more continuous than dichotomous, this simple categorization of the LAD is helpful. It would be interesting in a larger study with robust statistical power and including prospective and ongoing collection of data to refine the hazard ratio for mortality with a wraparound LAD versus a shorter vessel. Since the present study had a relatively small cohort, important and well-established factors known to predict and
affect mortality, such as age, Killip Class, myocardial blush score, and left ventricular function, were not found to be different between the two groups and were not predictive of subsequent mortality over many years. Another challenge with retrospective or isolated assessments in time is the absence of information regarding subsequent care or events. Fortunately, cardiovascular medicine has numerous effective therapies for STEMI treatment, such as aspirin, statins, betablockers, angiotensin converting enzyme inhibitors, cardiac rehabilitation, and internal defibrillators, to name but a few, and each of these clearly impacts mortality rates. REFERENCES 1. Lee KL, Woodlief LH, Topol EJ, Weaver WD, Betriu A, Col J, Simoons M, Aylward P, Van de Werf F, Califf RM. Predictors of 30-day mortality in the era of reperfusion for acute myocardial infarction. Results from an international trial of 41,021 patients. GUSTO-I Investigators. Circulation 1995;91:1659–1668. 2. Ilia R, Weinstein JM, Wolak A, Gilutz, Cafri C. Length of left anterior descending coronary artery determines prognosis in acute anterior wall myocardial infarction. Cathet Cardiovasc Interv 2014;84:316–320.
Catheterization and Cardiovascular Interventions DOI 10.1002/ccd. Published on behalf of The Society for Cardiovascular Angiography and Interventions (SCAI).
