Vol.48 - Número 3, Julio/Septiembre 2019 Imprimir sólo la columna central

Correlation between mean platelet volume and aortic valve sclerosis

HAMIDREZA VARASTEHRAVAN, MOHSEN AHMADZADE,
HOSSEIN NOUGH, ARYAN NAGHEDI
Hospital Shahid Sadoughi, Universidad de Ciencias Médicas Shahid Sadoughi.
Yazd, Irán
E-mail
Recibido 21-ENE-19 – ACEPTADO después de revisión el 28-FEBRERO-2019.
There are no conflicts of interest to disclose.

 


ABSTRACT

Aortic valve sclerosis (AVS) is a progressive clinical state with fibro-calcification and thickening of the aortic valve, without considerable occlusion confirmed by echocardiography. Mean platelet volume (MPV) is a complete blood count index (CBC) that indicates platelet activity. Numerous studies have reported that there is a close correlation between MPV and risk factors for cardiovascular disease. The aim of this study was to establish the correlation between MPV and AVS in patients referred to the cardiology department of the Shahid Sadoughi hospital.
Material and methods: After the echocardiographic evaluation of 134 patients for AVS, the patients were divided into two equal groups (positive AVS and negative AVS). Blood sampling was also performed. Echocardiographic data and serological findings were recorded as a questionnaire. SPSS 19 software was used for data analysis.
Results: Higher average age, hypertension, hyperlipidemia and diabetes mellitus are risk factors for AVS. Gender, smoking, HDL, LDL, triglycerides and total cholesterol however could not predict AVS. Patients with positive AVS have higher MPV compared to patients with negative AVS (9.93 ± 0.729 vs. 9.6 ± 0.965; P value = 0.012).
Conclusions: Diabetes mellitus, hypertension, hyperlipidemia and average age were recorded more frequently in patients with positive AVS compared to patients with negative AVS. There was a significant correlation between MPV and AVS.
Key words: Mean platelet volume. Aortic valve sclerosis. Cardiovascular risk factors.

 

INTRODUCTION
Aortic valve sclerosis (AVS) is a progressive clinical disease that is diagnosed by fibrosis and calcification confirmation or aortic valve thickening without obstruction or by high echogenicity in echocardiography, while valve movement is normal [1]. As AVS is a risk factor for cardiovascular diseases that may lead to a significant obstruction, observation and control of the disease seem to be a logical task [2]. Different studies showed that pathophysiology of AVS is associated to greater platelet aggregation, just as acute coronary syndrome (ACS) [1,3,4]. Also, greater prothrombotic activity with formation of clots on the calcified and/or stenotic aortic valve has been proven [5,6].

Some studies showed that mean platelet volume (MPV) makes greater platelet activity evident; an activity that plays a key role in pathophysiology of atherosclerotic diseases [7-9]; while other studies attenuate the correlation existing between MPV and cardiovascular diseases [10].

As a higher MPV may promote an acute coronary event with underlying inflammation and subsequent formation of thrombi, the correlation between MPV and AVS was investigated. If patients with AVS present a significantly higher MPV in the first stages of the disease, MPV could be considered a risk factor to predict cardiovascular thrombotic events and ACS. By controlling different co-morbidities as diabetes mellitus (DM) and hypertension between others, it is possible to reduce cardiovascular thrombotic events and the incidence of acute coronary event in patients with AVS.

 

MATERIALS AND METHODS
In this analytic, descriptive, cross-sectional study, patients were included who were referred to the Echocardiography Department of the Shahid Sadoughi Hospital, Yazd, Iran. Based on a consultation with statistical experts, a minimum of 134 patients were included. All patients were interviewed and evaluated, and a full physical test was made on them, with blood sample collection to determine MPV, glucose levels and plasma lipids.

The patients included were divided into two groups, according to the presence of AVS. There were 67 patients in the positive AVS group and the same number in the negative AVS group. Positive AVS was defined according: 1) presence of irregular thickening and high echogenicity (calcification) in aortic valve leaflets; 2) normal valve movement with no corner connection; 3) normal or minimally elevated Doppler flow (below 2 m/s) within the valve.

The exclusion criteria for the target population in this study were patients with diagnosed atherosclerotic disease, heart failure, rheumatic aortic valve disease, aortic insufficiency, aortic stenosis, consumption of lipid-lowering agents for more than 4 months, chronic kidney disease and prosthetic valve implant.

Determining MPV is a lab test, included in the full hemogram, easy to execute and available to assess platelet activity. Normal MPV was defined between 9.4 fL and 12.3 fL [11-13].

To define diabetes mellitus, glucose levels in blood >126 were considered in the blood sample obtained in a fasting state (measured twice), or patients receiving anti-diabetic agents. Hyperlipidemia or dyslipidemia was defined by levels ≥160 mg/dl of LDL (low-density lipoprotein) or triglycerides ≥200 mg/dl, total cholesterol ≥240 mg/dl in a blood sample, or in patients receiving lipid-lowering agents. Hypertensive patients were considered to have blood pressure >140/90 mmHg or those receiving anti-hypertensive agents.

Finally, all data of patients, along with the results of echocardiography, MPV and co-morbidities were recorded in a form. The data obtained were analyzed using the SPSS 19 software, using the different statistical tests, such as the T test and the Mann-Whitney U test.

To estimate the correlation between AVS and MPV, age and triglycerides, the Mann-Whitney U test was used, based on the statistical consultations received.

To establish the correlation between AVS and gender, hypertension, diabetes mellitus, hyperlipidemia and smoking, the Chi square test was applied.

To measure the correlation between AVS and total cholesterol, HDL and LDL, the T test was used.

 

RESULTS
This study showed a significant correlation between AVS and MPV, age, hypertension, DM and hyperlipidemia, with no significant correlation between AVS and gender, smoking, total cholesterol, LDL, high-density lipoproteins (HDL) and triglycerides.

In Table 1, the detailed statistics of the variables considered are given.   

Tabla 1. Significance levels of the variables assessed in this study.
    Variables AVS (+) AVS (-) P value
  MPV (fL) 9.93 ± 0.729 9.6±0.965 0.012
  Age (years) 65.3±7.25 48.1±8.27 0.000
  Gender (M/F) % 67.2/32.8 79.1/20.9 0.119
  Hypertension % 50.7 20.9 0.001
  Diabetes Mellitus % 59.7 31.3 0.001
  Hyperlipidemia % 41.8 23.9 0.027
  Smoking % 35.8 26.9 0.264
  Total cholesterol 194.91±51.783 182.69±52.759 0.178
  HDL (mg/dl) 38.79±10.582 38.88±10.823 0.961
 

LDL (mg/dl)

122.19±42.15 116.79±45.6 0.478
  Triglycerides (mg/dl) 157.7±100.77 133.49±77.55 0.179

 

 

DISCUSSION
This study evaluated the relationship between MPV estimated in the laboratory by a routine test and AVS by echocardiography. MPV was significantly higher in patients with AVS in comparison to patients without AVS.

Aortic valve sclerosis is a clinical entity that may progress into valve stenosis and is considered a risk factor for cardiovascular diseases [2]. Different studies showed that the pathophysiology of AVS is similar to acute coronary syndrome in the early stages of the disease and is associated to higher platelet aggregation [1,3,4]. Recent studies have shown that a higher prothrombotic activity and the subsequent formation of thrombi may occur in patients with stenotic or calcified aortic valve [5,6]. Numerous studies have been published, showing MPV to be an indicator on the level of platelet activity, key in the pathophysiology of atherosclerotic diseases [14,15], showing the relationship existing between increased MPV and cardiovascular diseases [7,8].

On the other hand, Giuseppe De Luca et al, reported in a study with 1411 patients, that MPV did not present a significant relationship with platelet aggregation and cardiovascular diseases [10].

  • The results of the study conducted in the Shahid Sadoughi Hospital, Yazd, Iran, on 134 patients, showed that there was a statistically significant correlation between MPV and AVS.

Ercan Varol et al, in 2011, on 43 patients with aortic stenosis, demonstrated that MPV in these patients is significantly higher than in the control group [16].

Emine Bilen et al, in 2012, in another study with 39 patients with bicuspid aortic valve, concluded that the bicuspid aortic valve correlates to an increase in MPV [17].

Sait Demirkol et al, in 2012, on 236 patients, 76 with cardiac syndrome X, 78 with CAD and 82 individuals in the control group, reported that patients with cardiac syndrome X and CAD presented MPV significantly higher in comparison to the control group [18].

In a similar study conducted by Murat Sucu et al, in Turkey, in 210 patients from whom 150 presented AVS and 60 had no AVS, it was reported that there was a strong relation between AVS and MPV, and that MPV is significantly higher in patients with AVS in comparison to the group with no AVS (9.5±3.1 vs 9.1±1.0, P value=0.022). The average age of patients with AVS was greater than those with no AVS, in a statistically significant manner (64.5±11.5 in comparison to 49.8±15.7, P value=0.001).

  • The MPV of the 67 patients from the Shahid Sadoughi Hospital, Yazd, Iran, with AVS was significantly higher than in the 67 patients with no AVS (9.93±0.729 vs 9.6±0.965, P value=0.012).

In two independent studies performed by Freeman and Otto, it was shown that aortic valve sclerosis without obstruction is common in older adults (>65 years) [19-23].

  • The population studied in the Shahid Sadoughi Hospital, Yazd, Iran, also confirmed the results from previous studies, in which patients with AVS presented an average age that was significantly higher when compared to patients without AVS (65.3±7.25 vs 48.1±8.27, P value=0.000).

In a study performed by Boon et al, in 1997, it was reported that factors like age, DM and hypertension are risk factors for atherosclerotic heart diseases and also risk factors for AVS [24]. Recent studies showed that common risk factors for atherosclerosis like HDL decrease, LDL increase, hypertriglyceridemia, hypercholesterolemia, smoking, hypertension and DM also may increase the risk of AVS [19,25-28].

In more recent trials, the relationship between increased MPV and common risk factors for cardiovascular diseases (DM, hypertension, dyslipidemia) is significant. Bancroft et al, showed that MPV decreases with age [29], with no link to gender.

  • There is to this date, no sound information available on the relationship, in patients with no AVS, between MPV and the risk factors mentioned above; in this sense, the findings obtained in this study (MPV was significantly higher in patients with AVS) are a contribution that may strengthen what was reported in literature.
  • The population of the Shahid Sadoughi Hospital, object of this trial, had an average age lower than the populations studied by Murat Sucu and Giuseppe De Luca, which makes a comparison between these populations difficult and limits it.

Taking into account the fact that in this study, the population was smaller than that of Murat Sucu and Giuseppe De Luca because of the limitations of our hospital, it is suggested that in future investigators similar studies should be performed with a wider study population, adding the normal population of standard society and to verify the relationship between MPV and AVS according to age, gender and other risk factors, just as in our study.

 

CONCLUSIONS
According to the findings of this study, and as mean platelet volume is an easily available tool and not expensive, it is considered reasonable for this hematological index to be used to estimate platelet volume increase, a prediction factor for prevention of cardiovascular events of the thrombotic kind.

 

 

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Publication: September 2019



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