Cardiothoracic ratio within the 'normal' range independently predicts mortality in patients undergoing coronary angiography

M Justin S Zaman ^1*, Julie Sanders ¹, Angela Crook ¹, Gene Feder ², Martin Shipley ¹, Adam Timmis ² and Harry Hemingway ¹

¹ University College London, United Kingdom
² Queen Mary's School of Medicine and Dentistry, United Kingdom

^* To whom correspondence should be addressed. E-mail: j.zaman{at}ucl.ac.uk.

Accepted 21 October 2006

Abstract

Objective We aimed to determine whether cardiothoracic ratio (CTR) within the range conventionally considered normal predicted prognosis in patients undergoing coronary angiography.

Design Cohort study with a median of 7 years follow-up.

Setting Consecutive patients undergoing coronary angiography at Barts and The London NHS Trust.

Subjects 1005 patients with cardiothoracic ratios measured by chest radiography and who subsequently underwent coronary angiography. 7.3% of these patients had a CTR 0.5 and were excluded from the analyses.

Outcomes All cause mortality and coronary event (non-fatal myocardial infarction or coronary death). Adjustments were made for age, left ventricular dysfunction, ACE inhibitor treatment, body mass index, number of diseased coronary vessels and past coronary artery bypass surgery (CABG).

Results The risk of death was increased among patients with a CTR in the upper part of the normal range. 94 (18.9%) of those with a CTR below the median of 0.42 died compared to 120 (27.8%) of those with a CTR between 0.42 and 0.49 (log-rank test p<0.001). After adjusting for potential confounders, this increased risk remained (adjusted hazard ratio 1.45, 95% CI 1.03-2.05). CTR, at these values of cardiothoracic ratio below 0.5, was linearly related to risk of coronary event (test for trend p= 0.024).

Conclusion In patients undergoing coronary angiography, CTR between 0.42 - 0.49 was associated with higher mortality than in patients with smaller hearts. There was evidence of a continuous increase in risk with higher CTR. These findings, along with those in healthy populations, question the conventional textbook cut-point of 0.5 being an abnormal CTR.

Keywords: cardiothoracic ratio, coronary artery disease, prognosis

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