The accuracy of the electrocardiogram during exercise stress test based on heart size.

BACKGROUND: Multiple studies have shown that the exercise electrocardiogram (ECG) is less accurate for predicting ischemia, especially in women, and there is additional evidence to suggest that heart size may affect its diagnostic accuracy. HYPOTHESIS: The purpose of this investigation was to assess the diagnostic accuracy of the exercise ECG based on heart size. METHODS: We evaluated 1,011 consecutive patients who were referred for an exercise nuclear stress test. Patients were divided into two groups: small heart size defined as left ventricular end diastolic volume (LVEDV) <65 mL (Group A) and normal heart size defined as LVEDV ≥65 mL (Group B) and associations between ECG outcome (false positive vs. no false positive) and heart size (small vs. normal) were analyzed using the Chi square test for independence, with a Yates continuity correction. LVEDV calculations were performed via a computer-processing algorithm. SPECT myocardial perfusion imaging was used as the gold standard for the presence of coronary artery disease (CAD). RESULTS: Small heart size was found in 142 patients, 123 female and 19 male patients. There was a significant association between ECG outcome and heart size (χ(2) = 4.7, p = 0.03), where smaller hearts were associated with a significantly greater number of false positives. CONCLUSIONS: This study suggests a possible explanation for the poor diagnostic accuracy of exercise stress testing, especially in women, as the overwhelming majority of patients with small heart size were women.

Relationship between the angiographically derived SYNTAX score and outcomes in high-risk patients undergoing percutaneous coronary intervention.

UNLABELLED: Numerous risk scores have been designed to predict the outcome of percutaneous coronary intervention (PCI). The Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) score has been shown to predict outcome in patients with severe coronary artery disease (CAD) randomized to PCI or bypass surgery, but its utility in patients with less severe CAD is less well established. METHODS: We calculated the SYNTAX score in 482 patients with diabetes mellitus or chronic kidney disease (serum creatinine > 1.5 mg/ml) undergoing non-emergency PCI. The study endpoint was 3-year all-cause mortality or repeat revascularization. RESULTS: The mean age was 69 ± 11 years, 44% were women, 82% had diabetes and they had 1.82 ± 0.78 diseased vessels. The mean creatinine clearance was 67.3 ± 37.2 ml/min. The mean SYNTAX score was 11 ± 8, median of 9 (5-15), tertiles < 7, 7-12 and > 12. There was good interobserver concordance (0.784 and 0.816, p < 0.01, respectively among two pairs of observers). The 3-year estimated survival rate was 0.85 (95% confidence interval [CI] 0.82-0.88). By multivariable analysis, creatinine clearance (hazard ratio [HR] 0.82 per 10 ml/min, p < 0.001), ejection fraction (HR 0.82 per 10%, p = 0.004) and prior infarction (HR 1.7, p = 0.03) were the only predictors of death. The SYNTAX score did not predict mortality. The incidence of repeat PCI by increasing tertiles of SYNTAX score was 19.2%, 32.2% and 33.2%, respectively, p < 0.001. CONCLUSION: In patients at high risk for ischemic events without severe CAD, the SYNTAX score is not associated with mortality at 3 years.

Utility of brain natriuretic peptide as a predictor of atrial fibrillation after cardiac operations.

BACKGROUND: Atrial fibrillation (AF) occurs frequently after coronary bypass grafting and valve operations. Brain natriuretic peptide (BNP) has been shown to predict recurrence of AF in congestive heart failure. It is a potential biomarker for preoperative risk stratification for development of AF in at-risk patients. METHODS: A total of 398 consecutive patients were prospectively evaluated for new-onset AF after heart operations. Patients with a history of AF and presence of permanent pacemaker were excluded. BNP levels were measured before and immediately after the operation. RESULTS: AF occurred in 20%. AF was more likely to develop in patients who were older, who underwent valve operations, had a lower ejection fraction, and a larger left atrial size. Preoperative exposure to statins (62% vs 43%, p < 0.01) and angiotensin inhibitors (60% vs 45%, p = 0.02) was more common in patients without AF. BNP values were insignificantly higher preoperatively (361 vs 302 mg/dL, p = 0.3) and postoperatively (312 vs. 229 mg/dL, p = 0.15) in patients with AF. Multivariate logistic analysis showed that older age (odds ratio [OR], 3.1, 95% confidence interval [CI], 1.7 to 5.6), lower ejection fraction (OR, 2.0; 95% CI, 1.2 to 3.3), larger left atrial size (OR, 3.1; 95% CI, 1.9 to 4.9), and nonuse of angiotensin inhibitors (OR, 2.3; 95% CI, 1.1 to 4.8) were independently associated with AF. CONCLUSIONS: This study does not support use of BNP for prediction of AF. Age, low ejection fraction, large left atrial size, and nonuse of angiotensin blocking agents were found to be significant predictors of AF development.