Using TAPSE versus speckle tracking in assessment of right ventricular function in healthy heavy chronic cigarette smokers

INTRODUCTION

Smoking increases risks of cardiovascular mortality and morbidity by multiple potential mechanisms including: vascular dysfunction, increased inflammation, progression of atherosclerosis, development of thrombi, oxidative stress and mitochondrial damage to myocytes. ¹

The right ventricle (RV) was considered the heart's neglected side, with little attention devoted to its assessment. ²

Speckle tracking, a relatively recent method, indicated that chronic heavy smokers with chronic obstructive pulmonary disease (COPD) had echocardiographic indications of right ventricular dysfunction even before the onset of pulmonary hypertension and cor pulmonale. Strain rate imaging parameters can detect right ventricular dysfunction in addition to traditional echocardiographic indices and are correlated with pulmonary hypertension and respiratory function testing.³ Reduced RV systolic function was present (sub-clinically) even in patients with COPD who did not have pulmonary hypertension compared with controls. ^{4 5}

However, the few studies that have focused on the smoking impact on right ventricular function, independent of coronary artery disease and COPD, have shown conflicting results.

Right ventricular functions may be appreciated with different techniques such as catheterization, nuclear magnetic resonance imaging and echocardiography.

Several echocardiography parameters such as fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), tricuspid annular systolic velocities, myocardial performance index (MPI) derived by tissue Doppler imaging have been thoroughly described in the evaluation of RV functions.⁶

Several studies have shown that 2D speckle tracking of the RV and RA can be utilised to assess the physio-mechanics of the right heart. Furthermore, it may offer parameters of load status, that is particularly significant in patients with right heart diseases.⁷

We aimed by this work to evaluate right ventricular functions in healthy heavy chronic cigarette smokers using conventional echocardiography (measuring TAPSE) and speckle tracking echocardiography as a non-invasive method of assessment.

PATIENTS AND METHODS

This study is a Multicenter, cross –sectional, comparative study was conducted in Sayed Galal University Hospital and General Air force hospital from November 2020 to September 2021.

The final study population were 300 males; 200 of them were apparently healthy heavy chronic cigarette smokers (Group I) and 100 apparently healthy non-smokers (Group II) of matched age, gender and risk factors.

Inclusion criteria include apparently healthy current cigarette smokers with at least 5 pack-years of smoking history and a daily cigarette consumption of at least 1 pack per day (20 cigarettes). Pack-years are determined by dividing the average number of cigarettes smoked each day by 20 and multiplying by the number of years of smoking.⁸

Exclusion criteria include patients who have one or more of the following: suboptimal echocardiographic image, more than one of the six RV segments lacking clearly defined boundaries, substance abuse, obese patients with BMI more than 30 kg/m²), COPD, elevated Pulmonary artery systolic pressure (PASP) ≥ 35 mmHg⁶, valvular heart disease, myocardial heart disease, patient with EF < 50%, coronary artery disease, moderate to severe pericardial disease, congenital heart disease, significant valvular heart disease, non-sinus rhythm or patient refusal.

All population were subjected to: full history taking (including age, sex, DM, HTN and smoking), full clinical examination (including pulse, blood pressure measurement and cardiac auscultation), pulse oximetry (to measure the oxygen saturation of blood), chest x-ray (to evaluate heart and lung condition), spirometry (to detect FEV1, FVC and FEV1/FVC ratio). The smokers were instructed to avoid smoking for at least 30 minutes before spirometry.

Electrocardiography (ECG):

Twelve lead surface ECG was done to assess patients’ heart rate and rhythm with the exclusion of ischemic changes or other ECG changes.

Echocardiography:

All images of the RA and RV were performed with the patients in the standard left lateral position in the apical-four chamber view with stable ECG reading using GE vivid 7 with 3S transducer (1.5-3.6 MHz. The smokers were advised to avoid smoking for at least 30 minutes and all the population not to consume coffee for at least 3 hours before the echocardiographic examination. All measurements were taken according to the last ASE guideline for chamber size assessment.⁹ Apical four-chamber view was done to evaluate the right side of the heart to assess:

Right ventricular dimensions:

The basal diameter was measured in basal 1/3 of the right ventricle, the mid-cavity diameter in the middle 1/3 of RV at the level of LV papillary muscles, and the longitudinal diameter was assessed by drawing a line from the plane of the tricuspid annulus to RV apex from an apical four-chamber view.

Right ventricular areas and fractional area change (FAC):

FAC was traced from a four-chamber image by the right ventricular endocardial from the annulus, down the free wall to the apex, and then back to the annulus, along the interventricular septum, in both systole and diastole.

Pulmonary artery systolic pressure (PASP):

PASP was calculated by using the tricuspid regurge jet's CW Doppler to calculate the systolic pressure gradient between RV and RA. The RVSP was calculated from the peak TR jet velocity using simplified Bernoulli equation then combining this result with RA pressure estimation: RVSP = 4(V)² + RA pressure, where V is the tricuspid valve regurge jet's peak velocity (in m/sec) and RA pressure is calculated from IVC diameter, collapsibility, and respiratory variations.

Tricuspid annular plane systolic excursion (TAPSE):

TAPSE was calculated by measuring the distance of the RV annular segment's systolic excursion along its longitudinal plane from a conventional apical 4-chamber window.

Assessment of left ventricular ejection fraction (LVEF):

The following formula was used to determine LVEF from left ventricular end-diastolic volume (EDV) and left ventricular end-systolic volume (ESV): (EDV- ESV)/EDV = EF This was accomplished by the use of a modified Simpson's rule.

Speckle tracking echocardiography:

Right atrial global longitudinal strain:

The RA longitudinal strain (RALS) was assessed by manual tracing the right atrium endocardium in 4 chamber images, defining six-segment zones. The software generated longitudinal strain curves for each atrial segment after analysing segmental tracking quality. RALS was evaluated in six RA segments. Peak RALS was determined at the end of the RA reservoir phase as the average of all RA segments to give the global RALS.¹⁰

Right ventricular global longitudinal strain (RV GLS):

At end-systole, by right ventricular tracing along the endocardium manually and automatic modification to accommodate the whole myocardium and to guarantee adequate tracking. The thickness of the myocardium was adjusted manually to the region of interest.¹¹

Right ventricular strain and strain rate are useful parameters for calculating the RV global and regional systolic functions. Longitudinal strain is measured as the proportion of systolic shortening of the RV free wall from base to apex, and longitudinal strain rate is the pace at which this shortening occurs.¹²

Statistical analysis:

The Statistical Package for Social Sciences was used for statistical analysis (version 26.0; SPSS Inc., Chicago, Illinois, USA). The mean and standard deviation were used to express the data. The independent t-test or one-way ANOVA was used to examine differences between groups. Pearson and Spearman coefficients of correlation were used to identify possible correlations. A P value < 0.05 was considered significant.¹³

RESULTS

Demographic data and smoking status:

The study included 300 males; 200 of them were healthy heavy chronic cigarette smokers (Group I) and 100 apparently healthy non-smokers (Group II). The age in both groups and indexes for the severity of smoking was reported in (Table 1 and Figure 1).

Fig 1: Comparing demographic parameters in both groups.

Blood pressure, pulse and smoking:

Pulse is lower in non-smokers than smokers with significant difference despite being within normal values in both groups.

Blood pressure measurements (either systolic, diastolic or calculated mean) were lower in non-smokers than smokers’ group but with minor differences that are statistically significant more in systolic and mean blood pressure than diastolic blood pressure. SBP was 120 ±7.521 in non-smokers’ group versus 122.5 ±7.878 in smokers’ group. DBP was 75.35 ±6.327 in non-smokers’ group versus 77.55 ± 6.340 in smokers’ group.

Oxygen saturation, spirometry and Smoking:

Oxygen saturation is higher in non-smokers than smokers with significant difference despite being within normal values in both groups.

Spirometry results didn’t signify any statistical difference between the 2 groups which may be due to the presence of other factors that affect FEV1 and FVC e.g., Body surface area. Yet, they had an important value to exclude chest diseases that may affect the right side of the heart. (Table 1 and Figure 2).

Fig 2: Comparing oxygen saturation and spirometry in both groups.

Left ventricular systolic function and smoking:

Smokers had a lower ejection fraction than non-smokers and the difference is statistically significant. The mean EF in smoker group was 61.11 ± 4.69%, while it was 68.29 ± 4.82% in non-smoker group (P<0.001).

Conventional parameters of RV parameters and smoking:

There is no statistically significant difference in right ventricular basal and middle diameters among the two groups. Right ventricular longitudinal diameter is otherwise more in smokers than non-smokers with a statistically significant difference.

TAPSE was more in non-smokers than smokers with a statistically significant difference.

Right ventricular end-diastolic and end-systolic areas were larger in smokers than non-smokers with subsequent better fractional area change in non-smokers than smokers with a statistically significant difference.

PASP is higher in heavy smokers than non-smokers with statistically significant difference (Table 2 and Figure 3).

RV speckle tracking and smoking:

Right ventricular global longitudinal strain was lower in non-smokers than smokers with statistically significant difference (Table 2 and Figure 4).

Right atrial end-systolic area and smoking:

Right atrial end-systolic area is higher in heavy smokers than non-smokers with a statistically significant difference.

Fig 3: Comparing RV parameters in both groups.

Fig 4: Comparing RV-GLS in both groups.

RA speckle tracking and smoking:

Right atrial global longitudinal strain is more in non-smokers than smokers with a statistically significant difference. (Table 2 and Figure 5).

Fig 5: Comparing RA parameters in both groups.

Correlation between RV indices:

By comparing different echo modalities of right ventricular function assessment i.e., TAPSE, FAC and RV GLS, using R coefficient, all methods have correlation being higher in TAPSE and FAC and moderate in GLS.

Table 1: Baseline demographic and clinical characteristics of the study population.

Table 2: Echocardiographic parameters of the study population.

Table 3: Demonstrating different correlations of coefficients between different methods to assess right ventricular functions.

Fig 6: Three simple scatters with fit line demonstrating different correlations of coefficients between different methods to assess right ventricular function.