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Background: Cardiac dysfunction is common in exacerbations of chronic obstructive pulmonary disease (COPD), even in patients without clinically suspected cardiac disorders. Aim: To investigate associations between electrocardiogram (ECG) and chest radiograph abnormalities and biochemical evidence of cardiac dysfunction (N‐terminal pro‐B‐type natriuretic peptide and troponin T) in patients hospitalised with exacerbations of COPD at Waikato Hospital. Methods: Independent examiners, blinded to NT‐proBNP and troponin T levels, assessed ECG for tachycardia, atrial fibrillation, ventricular hypertrophy and ischaemic changes in 389 patients and chest radiographs for signs of heart failure in 350 patients. Associations between electrocardiographic and radiographic abnormalities with at least moderate interrater agreement and cardiac biomarkers were analysed. Results: High NT‐proBNP values (>220 pmol/L) were associated with atrial fibrillation (22 vs 6%), right ventricular hypertrophy (24 vs 15%), left ventricular hypertrophy (15 vs 4%), ischaemia (59 vs 33%) and cardiomegaly (42 vs 20%). High troponin T values (>0.03ug/L or high‐sensitivity >50 ng/L) were associated with tachycardia (65 vs 41%), right ventricular hypertrophy (26 vs 15%) and ischaemia (60 vs 36%). None of the electrocardiographic or radiographic abnormalities was sensitive or specific for cardiac biomarker abnormalities. Ischaemia on ECG was the best indicator for raised NT‐proBNP (sensitivity 59%, specificity 67%). Tachycardia and ischaemia were the best indicators of raised troponin T (sensitivity 65 and 60%, specificity 59 and 64% respectively). Conclusions: ECG and chest radiograph abnormalities have poor sensitivity and specificity for diagnosing acute cardiac dysfunction in exacerbations of COPD. Cardiac biomarkers provide additional diagnostic information about acute cardiac dysfunction in exacerbations of COPD. [ABSTRACT FROM AUTHOR]