Cardiovascular malformations are the commonest type of congenital malformation, accounting for 6–10% of all infant deaths and 20–40% of all infant deaths from malformation.1 ,2 Most babies with serious cardiovascular malformations are asymptomatic at birth.3 Some of them deteriorate or die before the diagnosis is recognised.2 Earlier diagnosis, before clinical deterioration, ought to lead to an improvement in outcome.4

All babies are examined after birth before discharge from hospital. Although this examination is commonly regarded as a screening test, it is known to perform poorly in babies with life-threatening cardiovascular malformations, as there may be no abnormal physical signs before the development of symptoms.5 ,6 The opportunity for presymptomatic diagnosis may also be reduced by earlier discharge from hospital after delivery.

This study examines trends in the time of diagnosis of potentially life-threatening cardiovascular malformations over a 20-year period.

PATIENTS AND METHODS

RESULTS

In 1985–2004 there were 690 215 live births in the study population. A diagnosis of a cardiovascular malformation was made in 4444 (6.4 per 1000) and 669 (15%) of these met our criteria for life-threatening congenital cardiovascular malformation defined above. There was a 20% fall in the live birth rate from nearly 39 000 to around 30 000 per year, but there was no change in the prevalence at live birth of life-threatening cardiovascular malformations over the 20 years of the study, with a mean of 0.97 per 1000 live births.

Of 669 infants with life-threatening cardiovascular malformations, 55 (8%) had an antenatal diagnosis, 416 (62%) had a postnatal diagnosis before discharge from hospital, 168 (25%) were diagnosed in living infants after discharge from hospital and 30 (5%) were diagnosed only at autopsy. Figure 1 shows that over 20 years the proportion with an antenatal diagnosis increased to about 20% and overall there was a decrease in the proportion of cases diagnosed before discharge from hospital.

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Figure 1 Time of diagnosis by year of birth 1985–2004.

Cardiovascular malformations were undiagnosed at the time of discharge from hospital in 198 infants (30%) and in 30 of these the diagnosis was made only after death. Table 1 shows the timing of diagnosis of individual malformations. Figure 2 shows that the diagnoses most likely to be unrecognised at the time of discharge included coarctation of the aorta (54%), interruption of the aortic arch (44%), aortic valve stenosis and total anomalous pulmonary venous connection (37%).

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Figure 2 Time of diagnosis for individual malformations (ranked according to probability of predischarge diagnosis). For abbreviations see table 1.

Over 20 years the all-causes 12-month mortality for live born infants with life-threatening cardiovascular malformations fell from around 50% to around 20%.

There were 139 terminations of pregnancy in fetuses with a cardiovascular malformation. The majority had associated major chromosomal or other non-cardiac abnormalities, but 60 had isolated cardiovascular malformations which would meet our criteria for being potentially life-threatening in postnatal life. The rate of termination increased, with 14 in the first 10 years and 46 in the second 10 years.

We have no regional data on the length of hospital stay after birth.

DISCUSSION

Our study has found that around 30% of infants with potentially life-threatening cardiovascular malformations were undiagnosed at the time of discharge from hospital. This proportion fell to around 25% in recent years. Terminations of pregnancy increased, but there was no change in the prevalence at live birth of life-threatening cardiovascular malformations, which remained at around 1 in 1000 live births. Despite this, the total infant mortality for such babies has reduced substantially.

Earlier postnatal recognition of potentially serious cardiovascular malformations should contribute to reduction in morbidity and mortality.4 ,9 There is also evidence that prenatal diagnosis improves postnatal outcome for a number of malformations, including transposition of the great arteries,10 hypoplastic left heart11 and coarctation of the aorta.12

There have been few other studies of the timing of diagnosis of potentially life-threatening cardiovascular malformations. In a recent report Mellander and Sunnegårdh investigated postdischarge diagnosis in neonates and young infants with critical heart disease.13 They included all infants requiring surgery or catheter intervention in the first 2 months of life and thus had a wider range of diagnoses over a longer time period than our study. Mellander and Sunnegårdh found that 50% of their patients had duct-dependent systemic circulation, 41% had duct-dependent pulmonary circulation and 9% were not duct dependent. The proportion of their patients diagnosed after discharge from hospital averaged 20% but doubled over 9 years. Their study did not include patients not referred for surgery or dying before diagnosis and could not take account of changes in prenatal diagnosis or termination of pregnancy.

In a much smaller study from a hospital with only 2300 births a year Meberg et al reported a lower rate of late diagnosis.14 They also found that coarctation of the aorta and aortic valve stenosis were the potentially dangerous malformations most likely to be overlooked before discharge.

Influences on the speed of recognition of life-threatening cardiovascular malformations include antenatal diagnosis, the speed of referral of babies with a clinical suspicion of congenital heart disease and the length of stay in the maternity hospital after birth. We are unaware of any published data from the United Kingdom on age at discharge, but reports from Sweden, the United States and Canada show a reduction from 4 or 5 days in the 1980s to 1–3 days in the 1990s.15^–19 It is likely that the trend towards earlier discharge in our population mirrors that in the UK nationally, with an increasing proportion of babies being sent home 6–12 hours after delivery.

In a previous study we found that the diagnosis of cardiovascular malformations is often delayed despite the detection of a murmur at the first neonatal examination.5 It is impractical to refer all neonates with murmurs for urgent paediatric cardiology assessment, but if a significant murmur is detected and echocardiography skills are available in the neonatal unit, earlier diagnosis of potentially serious cardiovascular malformation ought to lead to a better outcome.20 ,21

Given the failure of clinical examination to increase the number of babies with serious heart disease detected before discharge, any improvement is likely to come from a different strategy. This will include further improvements in antenatal diagnosis,22 more widespread adoption of routine pulse oximetry in the newborn,23^–25 and better education of midwives and other primary healthcare professionals that the absence of physical signs at birth does not mean that there is no life-threatening problem.3 The trend towards a shorter postnatal length of stay is likely to continue.