Michael S. Lauer

Myocardial Viability Testing and the Effect of Early Intervention in Patients With Advanced Left Ventricular Systolic Dysfunction

Background— The clinical value of revascularization and other procedures in patients with severe systolic heart failure is unclear. It has been suggested that assessing ischemia and viability by positron emission tomography (PET) with fluorodeoxyglucose (FDG) imaging may identify patients for whom revascularization may lead to improved survival. We performed a propensity analysis to determine whether there might be a survival advantage from revascularization. Methods and Results— We analyzed the survival of 765 consecutive patients (age 64±11 years, 80% men) with advanced left ventricular systolic dysfunction (ejection fraction ≤35%) and without significant valvular heart disease who underwent PET/FDG study at the Cleveland Clinic between 1997 and 2002. Early intervention was defined as any cardiac intervention (surgical or percutaneous) within the first 6 months of the PET/FDG study. In the entire cohort, 230 patients (30%) underwent early intervention (188 [25%] had open heart surgery, most commonly coronary artery bypass grafting, and 42 [5%] had percutaneous revascularization); 535 (70%) were treated medically. Using 39 demographic, clinical and PET/FDG variables, we were able to propensity-match 153 of the 230 patients with 153 patients who did not undergo early intervention. Among the propensity-matched group, there were 84 deaths during a median of 3 years follow-up. Early intervention was associated with a markedly lower risk of death (3-year mortality rate of 15% versus 35%, propensity adjusted hazard ratio 0.52, 95% CI 0.33 to 0.81, P=0.0004). Conclusions— Among systolic heart failure patients referred for PET/FDG, early intervention may be associated with improved survival irrespective of the degree of viability.

Quantitative Measures of Electrocardiographic Left Ventricular Mass, Conduction, and Repolarization, and Long-Term Survival After Coronary Artery Bypass Grafting

Background— Quantitative ECG measures of left ventricular mass and repolarization predict outcome in population-based cohorts and patients with hypertension. We assessed the prognostic value of preoperative quantitative electrocardiography in patients who underwent isolated coronary artery bypass grafting. Methods and Results— For 6 years we followed 8166 patients who underwent primary isolated coronary artery bypass grafting between 1990 and 2003, all of whom had routine preoperative ECGs. With use of specialized digital software, quantitative measures were recorded on ventricular rate, P duration, PR interval, QRS duration, QT interval, QRS axis, Sokolow-Lyon and Cornell voltages, and ST-segment depression and slope. There were 1516 deaths. After adjustment for age, gender, clinical characteristics, left ventricular ejection fraction, and other confounders, death was independently predicted by ventricular rate (adjusted hazard ratio [AHR] for 90 versus 60 beats per minute, 1.34; 95% confidence interval [CI], 1.21 to 1.50; P<.0001), PR interval (AHR for 200 versus 150 ms, 1.05; 95% CI, 1.00 to 1.10; P<.0001), QRS duration (AHR for 120 versus 80 ms, 1.24; 95% CI, 1.07 to 1.44; P<.0001), Sokolow-Lyon voltage (AHR for 3.5 versus 1.5 mV, 1.18; 95% CI, 1.05 to 1.31; P<.0001), and ST-segment slope (AHR for −0.1 versus 0 mV, 1.16; 95% CI, 1.02 to 1.31; P<.0001). We derived a quantitative ECG score and demonstrated that, with the exception of age, it was the most powerful predictor of long-term death. Conclusions— Quantitative ECG measures of left ventricular rate, mass, and repolarization are predictive of mortality among patients who underwent isolated coronary artery bypass grafting. These findings suggest that quantitative electrocardiography may be valuable for risk stratification in patients with severe coronary artery disease.

Cardiac Troponins and Renal Failure The Evolution of a Clinical Test

In this issue of Circulation , Khan and colleagues present the results of an elegantly performed meta-analysis of the prognostic implications of elevated levels of troponin T and I among asymptomatic patients with end-stage renal disease.1 After systematically collating the results of 28 cohort studies involving 3931 patients, they noted that an elevated troponin T level identified a group of end-stage renal disease patients with high mortality risk. Although elevated troponin I was also associated with increased risk, the exact effect size was difficult to assess because of a lack of standardization of current assays. The authors noted that despite the consistent association between elevated troponin T and mortality, the effect might be overestimated because of publication bias and study heterogeneity. Nonetheless, this meta-analysis, along with the specific reports of the largest published cohort studies,2,3 provides robust evidence that troponin T elevation in the setting of end-stage renal disease is ominous. Article p 3088 The development of troponin measurement in the absence of end-stage renal disease is an excellent paradigm for the modern evolution of clinical tests. Troponin T and troponin I are both integral parts of the cardiac muscle infrastructure and play critical roles in excitation-contraction coupling.4 The diagnostic importance of troponin elevation stems from its release into the bloodstream when there is some type of damage to cardiac myocyte cell-wall integrity.5 The high sensitivity of troponin for detecting even small myocardial infarctions has led to widespread recommendations for its routine measurement for the diagnosis of myocardial infarction.6 It could be argued, though, that were elevated troponin to diagnose myocardial infarctions that were of little prognostic …