Many studies have shown that people with psoriasis have a higher risk of cardiovascular disease when compared with the general population. This is generally believed to be due to a higher prevalence of cardiovascular risk factors such, hypertension, smoking, raised cholesterol levels and diabetes, leading to blockages plaque deposits in the in the coronary arteries (the blood vessels supplying the heart). When these deposits become so marked that the blood supply to the heart muscle is no longer adequate, the patient may suffer symptoms such as angina or a heart attack. This is called obstructive coronary artery disease (CAD), obviously because of the blockages in the main arteries.
However, in recent years, more attention has been paid to the microcirculation of the heart – the system of tiny capillaries that provide the heart muscle with blood and oxygen. Disease in this system of blood vessels is called coronary microcirculatory dysfunction (CMD). CMD has been shown to be a predictor of cardiovascular disease, both in the general population and in patients with psoriasis. However, measuring CMD directly is very expensive and time-consuming. Instead, measuring coronary flow reserve (CFR) with a form of ultrasound (echocardiography), has been shown to be an accurate and relatively easy way to assess CMD. Importantly, reduced CFR consistently identifies patients at increased risk of heart attack and death.
In this study, investigators assessed the prevalence of reduced CFR in patients with severe psoriasis, using echocardiography. The study population consisted of 448 psoriatic patients (69% male) with an average age of 45 years. Severity of psoriasis was assessed using the Psoriasis Area and Severity Index (PASI) score, the duration of the disease and current medication. The average duration of psoriasis was 15.2 years and the average PASI score was 12.
Note that because a reduced CFR can occur in both CMD and obstructive coronary disease, patients who were found to have a low CFR, then underwent a procedure called angio-CT to exclude major blockages (stenoses) in the coronary arteries. None of the 448 subjects were found to have obstructive coronary disease, so all patients with an impaired CFR in this study, were affected by disease of the microcirculation (CMD).
In all, a total of 141 (31.5%) of patients showed evidence of CMD. The study revealed that psoriasis severity, hypertension, the duration of the disease and the presence of psoriatic arthritis, were all independently associated with a higher risk of CMD – as confirmed by lower CFR measurements. Interestingly, other conventional cardiovascular risk factors, such as smoking, raised cholesterol levels and diabetes, did not predict microcirculatory heart disease.
Previous studies have shown that people with severe psoriasis have an increased cardiovascular morbidity and mortality. However, there has been limited research on the specific mechanisms underlying this increased risk. This study suggests that heart disease in patients with psoriasis, may involve two mechanisms:
- Blockage of main coronary arteries due to standard risk factors such as smoking, diabetes, raised cholesterol levels etc, and
- CMD – damage to the microcirculation of the heart due to the generalised inflammation associated with psoriasis.
Clearly both forms of the disease may be found together, but they may also exist independently. In this study, almost one-third of patients with psoriasis had evidence of CMD, in the absence of any arterial blockages or symptoms of heart disease. Moreover, the absence of traditional risk factors in a patient with psoriasis, would not exclude the possibility of an increased risk of cardiovascular disease, due to CMD. As the authors point out, CFR may have a role as a screening test for CMD, in patients with severe psoriasis, along with standard risk factors.
More research is needed
We need prospective studies to establish whether the presence of CMD, is a better predictor of morbidity and mortality from cardiovascular disease, than traditional risk factors. We also need to understand whether earlier and more aggressive treatment for psoriasis with biologic agents, would bring about an improvement in CMD and a reduced risk of cardiac disease.
In the meantime, this study emphasises yet again, that psoriasis is a systemic inflammatory disease which may have detrimental effects well beyond the skin.
Reference: Piaserico S, Papadavid E, Cecere A, et al. Coronary Microvascular Dysfunction in Asymptomatic Patients with Severe Psoriasis. Journal of Investigative Dermatology, 2023; 143, 1929-1936