Erectile dysfunction (ED) is common and its incidence increases with age. It is estimated that 140 million men worldwide have some degree of ED, and by 2025 the prevalence is predicted to increase to more than 300 million.
The Massachusetts Male Ageing Study recorded a prevalence of ED in 52 per cent of men aged 40–70 years, increasing to 70 per cent in those aged 70 or more. It can result in the man losing self-esteem, feeling inadequate and becoming depressed, and is an important cause of relationships breaking down.
With the increased awareness of ED as a consequence of the introduction of sildenafil has come a better understanding of the mechanisms responsible. Previously believed to be predominantly a psychological problem, it is now recognised that vascular disease is the major cause, with endothelial dysfunction the common denominator.
It is, however, important not to compartmentalise ED, because the negative psychological impact of vascular ED must be recognised and managed.
Because vascular disease shares the same risk factors for ED (smoking, hypertension, diabetes, hyperlipidaemia, obesity, lack of exercise), the question arises: does ED coincide with or follow the development of coronary symptoms, or might it precede them and act as an early marker of coronary artery disease (CAD)?
ED as a disease marker
Pritzker studied 50 men aged 40–60 asymptomatic for coronary disease but who had ED. Eighty per cent had multiple cardiovascular risk factors.
Exercise ECGs were abnormal in 28 of the subjects, with subsequent angiography in 20 men identifying severe CAD in six, moderate two-vessel disease in seven and significant single-vessel coronary artery disease in another seven.
In our study of 132 men attending day-case angiography for stable ischaemic symptoms, 40 per cent had experienced ED before their CAD diagnosis.
ED has been shown to worsen as the extent of CAD increases and can therefore act not just as a marker of its presence, but also of its severity.
It has been proposed that the smaller penile arteries (diameter 1–2mm) suffer greater disruption from plaque burden and endothelial dysfunction than the larger coronary arteries (3–4mm). Acute coronary syndromes follow rupture of subclinical lipid-rich plaques, so this observation suggests that ED might be a predictor of acute as well as stable coronary artery disease presentation.
This was shown to be the case in 300 men with acute chest pain and angiographically-proven CAD, 65 per cent of whom had ED before their presentation, with an average delay to chest pain of three years.
In a health screening programme, moderate to severe ED was shown to be associated with a significant increase in CAD (relative risk versus no ED was 65 per cent) and stroke risk (relative risk increase was 43 per cent) over 10 years.
In a prospective angiographic study, nine of 47 men with ED (19 per cent) had angiographically silent CAD. In the Prostate Cancer Prevention Trial, 8,053 men aged 55 or older had no cardiovascular disease at entry in 1994, when 3,816 (47 per cent) had ED.
Among the 4,247 men without ED, 2,420 (57 per cent) developed it after five years. After nine years’ follow-up, the men with ED at entry or those developing ED had an increased incidence of developing a cardiac event of up to 45 per cent, compared to those without ED.
Opportunity to cut risk
There is now overwhelming evidence that ED is a marker for CAD and all vascular disease, whether symptomatic or silent. Of importance is its development up to three years before a cardiac event, allowing time for intervention with aggressive risk reduction and careful clinical screening.
The Second Princeton Consensus on Sexual Dysfunction and Cardiac Risk concluded that ED was a warning sign of silent vascular disease and that a man with ED should be considered a cardiac or vascular patient until proved otherwise.
All men with ED and no cardiac symptoms should have a fasting lipid profile, glucose, and BP measurements, and be given advice about lifestyle. Ideally, they should also undergo non-invasive stress testing (for example, exercise ECG) to facilitate risk identification and reduction.
There is no doubt that ED is a marker for silent cardiovascular risk but as yet we have no large-scale prospective trial to test the benefit of risk reduction on cardiac events in men with ED.
However, given the information we do have regarding the primary and secondary prevention of vascular disease, an aggressive approach to these cases is warranted until formal studies are completed.
Dr Jackson is consultant cardiologist, Guy’s & St Thomas’ Hospital Foundation Trust
National Impotence Day is 14 February 2007. For more information see the Sexual Dysfunction Association website at www.sda.uk.net