Exercise-induced pulmonary hypertension in HIV patients: Association with
poor clinical and immunological status
Rosalinda Madonna a,1
, Silvia Fabiani b,1
, Riccardo Morganti c
, Arianna Forniti b
Matteo Mazzola a
, Francesco Menichetti b
, Raffaele De Caterina a,*
a Department of Pathology, Cardiology Division, Azienda Ospedaliera Universitaria Pisana, University of Pisa, Pisa, Italy b Infectious Disease Unit, Department of Clinical and Experimental Medicine, Azienda Ospedaliera Universitaria Pisana, University of Pisa, Italy c Institute of Epidemiology, University of Pisa, Pisa, Italy
ARTICLE INFO
Keywords:
Human immunodeficiency virus
Acquired immunodeficiency syndrome
Exercise-induced pulmonary hypertension
Stress echocardiography
ABSTRACT
Background and aim: Exercise-induced pulmonary hypertension (Ex-PH) may represent the earliest sign of pul￾monary arterial hypertension (PAH) in human immunodeficiency virus (HIV) patients. We investigated its as￾sociation with clinical and immunological status, virologic control, and response to antiviral therapy.
Methods: In 32 consecutive HIV patients with either low (n = 29) or intermediate probability (n = 3) of PH at rest,
we evaluated the association of isolated ExPH with: time to HIV diagnosis; CD4+ T-cell count; clinical pro￾gression to acquired immunodeficiency syndrome (AIDS); development of resistance to antiretroviral therapy
(ART); HIV RNA levels; time to beginning of ART; current use of protease inhibitors; combination of ART with
boosters (ritonavir or cobicistat); immuno-virologic response to ART; and ART discontinuation.
Isolated ExPH at stress echocardiography (ESE) was defined as absence of PH at rest and systolic pulmonary
arterial pressure (sPAP) >45 mmHg or a >20 mmHg increase during low-intensity exercise cardiac output
(<10 L/min).
Results: In our cohort, 22% (n = 7) of the enrolled population developed ExPH which was inversely related to
CD4+ T-cell count (p = 0.047), time to HIV diagnosis (p = 0.014) and time to onset of ART (p = 0.041). Patients
with ExPH had a worse functional class than patients without ExPH (p < 0.001). ExPH and AIDS showed a trend
(p = 0.093) to a direct relationship. AIDS patients had a higher pulmonary vascular resistance compared to
patients without ExPH (p = 0.020) at rest echocardiography.
Conclusions: The presence of isolated ExPH associates with a worse clinical status and poor immunological
control in HIV patients. Assessment of ExPH by ESE may help identify subgroups of HIV patients with a pro￾pensity to develop subclinical impairment of pulmonary circulation following poor control of HIV infection.
1. Introduction
Human immunodeficiency virus (HIV) infection is an established risk
factor for the development of pulmonary arterial hypertension (PAH)
[1]. This diagnosis is usually delayed due to the non-specificity of
symptoms, such as dyspnea on exertion and at rest, reported in
Abbreviations: AIDS, acquired immunodeficiency syndrome; ALK-1, activin-like kinase type 1; ART, antiretroviral therapy; BMPR2, bone morphogenic protein
receptor 2; EAE, European Association of Echocardiography; ECG, electrocardiogram; EF, ejection fraction; ERS, European Respiratory Society; ESC, European
Society of Cardiology; ESE, stress echocardiography; ET-1, endothelin 1; ExPH, exercise-induced pulmonary hypertension; FAC, fractional area change; Gp 120,
glycoprotein 120; HHV 8, human herpes virus 8; HIV, human immunodeficiency virus; HLA, human leukocyte antigen; 5-HTT, serotonin transporter; IL, interleukine;
LV, left ventricular; LVEF, left ventricular ejection fraction; Nef, negative regulatory factor; NO, nitric oxide; PAH, pulmonary arterial hypertension; PgI2, prosta￾cyclin 2; PH, pulmonary hypertension; PVRI, pulmonary vascular reserve index; RV, right ventricular; SD, standard deviation; sPAP, systolic pulmonary artery
pressure; STAT, signal transducer of activators of transcription; TAPSE, tricuspid annular plane systolic excursion; Tat, trans activator protein; TNFα, tumor necrosis
factor α; TRV, tricuspid regurgitant jet velocity; TTE, transthoracic echocardiography; WHO, World Health Organization; WHO-FC, World Health Organization￾Functional Class.
* Corresponding author.
E-mail address: [email protected] (R. De Caterina). 1 Equally contributed.
Contents lists available at ScienceDirect
Vascular Pharmacology
journal homepage: www.elsevier.com/locate/vph
Received 5 June 2021; Accepted 22 June 2021
Vascular Pharmacology 139 (2021) 106888
2
approximately 85% of patients [2]. Although the prognosis of HIV￾positive patients has improved dramatically over the past 20 years
with the availability of antiretroviral therapy (ART), the prevalence
(0.5%) and severity of HIV-associated PAH is similar as it was in the
early 1990s, when ART were not available [3–6]. This suggests that
factors other than direct action of HIV and immuno-virological response
to HAART (i.e., genetic predisposition and susceptibility) may play a
role, as seen for concomitant conditions affecting HIV patients. Conse￾quently, mortality of HIV patients affected by PAH is usually related to
PAH itself rather than to HIV-related complications, with PAH being an
independent predictor of death in such patients [7], thus warranting
early diagnosis.
Although unexplained exertional dyspnea is common among HIV
patients, isolated exercise-induced pulmonary hypertension (ExPH) due
to impaired pulmonary vascular and right ventricular (RV) contractile
reserve on effort is not well-described in HIV patients. On the contrary,
ExPH has been well characterized in other groups of patients at risk for
PH such as those with scleroderma [8,9], sickle cell disease [10] and
chronic obstructive pulmonary disease [11]. Some scleroderma patients
with ExPH progress to resting PH, suggesting that ExPH may be an early
marker of PH at rest [10,12]. We have previously shown that ExPH is
associated with higher cardiovascular risk and thus clinical worsening in
scleroderma patients [9], making the assessment of ExPH potentially
helpful to the early identification also of subgroups of HIV patients with
a propensity for PAH, in whom therapeutic strategies could be initiated
earlier to improve the immune status or the status of the pulmonary
circulation, with potential beneficial effects on quality of life and
mortality.
Here, we therefore hypothesized that isolated ExPH is associated
with poorer clinical and immunological status in HIV patients at risk for
PAH. Consequently, we investigated the association of isolated ExPH
with clinical determinants of the immunological status, virologic con￾trol, and response to antiviral therapy in HIV patients.
2. Methods
2.1. Study design and data collection
This was a prospective, observational, cohort study of 40 HIV pa￾tients recruited from the Infectious Disease Clinic of Pisa University
Hospital. The study complies with the Helsinki Declaration, and
informed consent was obtained from patients before any diagnostic test,
always performed for clinical purposes. Patients eventually selected for
the present report were later contacted and gave their approval for in￾clusion in the study protocol. The local investigators had full access to
patient data and medical records (Fig. 1).
All patients enrolled underwent transthoracic echocardiography
(TTE) followed by a transthoracic stress echocardiography (ESE). As
shown in the flowchart depicted in Fig. 2, according to TTE evaluation of
PH probability [13,14], patients included had either a “low” PH prob￾ability at rest [tricuspidal regurgitation velocity (TRV) ≤2.8 m/s or not
measurable, without additional PH signs, n = 29] or an “intermediate”
PH probability at rest (TRV ≤2.8 m/s or not measurable, with additional
PH signs; or TRV 2.9–3.4 m/s without additional PH signs, n = 3). We
excluded patients with a “high” PH probability (TRV 2.9–3.4 m/s with
additional PH signs, or TRV > 3.4 m/s, n = 8). Additional exclusion
criteria were the presence of moderate-to-severe anemia (hemoglobin
<10 g/dL); significant left heart disease at the resting TTE; history of
venous thromboembolism; severe kidney disease; or chronic obstructive
pulmonary disease – all possible additional causes of PH; and moderate
to severe tricuspid insufficiency.
ESE was performed according to the protocol recommended by the
European Association of Echocardiography (EAE) guidelines [15]. Iso￾lated ExPH at ESE was defined as the absence of PH at rest and either a
systolic pulmonary arterial pressure (sPAP) >45 mmHg; or a raise of
sPAP >20 mmHg during a low-intensity exercise (50 W over 2 min) not
exceeding a cardiac output (heart rate x stroke volume) of 10 L/min
[16–18]. Patients were thus classified as either with or without ExPH.
The two groups of patients were compared at baseline.
We evaluated the association of the dichotomous variable isolated
ExPH with: (1) patients’ demographics; (2) the time to HIV diagnosis;
(3) the CD4+ T cell count as an index indicator of immune function in
HIV patients; (4) clinical progression to acquired immunodeficiency
syndrome (AIDS); (5) development of resistance to ART; (6) HIV RNA
levels (copies/mL); (7) time to beginning of ART; (8) current use of
protease inhibitors; (9) the combination of ART with booster drugs (ri￾tonavir or cobicistat); (10) the immuno-virologic response to ART; (11)
ART discontinuation; (12) World Heart Organization functional class
(WHO-FC); (13) echocardiographic parameters.
2.1.1. Transthoracic echocardiography
We assessed the peak of TRV to determine the echocardiographic
probability of PH according to the recently updated ESC/ERS PH
guidelines [1,14]. Additionally, we sought echocardiographic PH signs,
classified as present if at least 2 of the 3 categories (A–C) were docu￾mented: (A) right ventricle/left ventricle basal diameter ratio > 1.0;
flattening of the interventricular septum (left ventricular eccentricity
index >1.1 in systole and/or diastole); (B) right ventricular acceleration
time < 105 ms and/or the presence of a mid-systolic notching; early
diastolic pulmonary regurgitation velocity > 2.2 m/s; pulmonary artery
diameter > 25 mm; (C) inferior vena cava diameter > 21 mm with
decreased inspiratory collapse (<50% with a sniff or < 20% with quiet
inspiration); right atrial area (end-systole) >18 cm2
. We assessed right
ventricular function by measuring the tricuspid annular plane systolic
excursion (TAPSE) and the fractional area change (FAC), according to
the guidelines of the American Society of Echocardiography [19]. Since
TAPSE and FAC can be load-dependent, we excluded from the study
patients with moderate and severe tricuspid insufficiency (see above).
We measured left ventricular ejection fraction (LVEF) using the biplane
Simpson’s method [19]. We classified valvular disease from trivial to
mild to moderate to severe according to current recommendations
[19–21].
2.1.2. Stress echocardiography
All patients underwent a semi-supine ESE performed with a 2.5-MHz
duplex transducer and conventional ultrasound system (Philips, Milan,
Italy) on a semi-recumbent cycle ergometer (Ergoline, model 900 EL,
Germany), according to the protocol recommended by the European
Association of Echocardiography (EAE) guidelines [15]. Graded cycling
was performed starting at an initial workload of 25 W lasting for 2 min.
HIV (n = 40)
Resting TT echocardiogram
Low and intermediate PH probability (n = 32) High PH probability (n = 8)
ESE for ExPH diagnosis excluded
ExPH yes (n = 7)
Anthropometric,
clinical data
co-treatments
Blood chemistry
data
Echocardiographic
parameters
ExPH no (n = 25)
Infectious disease
data
HIV therapy
Data collection and statistical analyses
Fig. 1. Study flowchart, illustrating the study from enrollment to data collec￾tion and statistical analyses. Abbreviations: ESE, exercise echocardiography;
ExPH, exercise-induced pulmonary hypertension; PG, pulmonary hypertension;
HIV, Human Immunodeficiency Virus; TT, transthoracic.
R. Madonna et al.
Vascular Pharmacology 139 (2021) 106888
3
The workload was gradually increased by 25 W at 2 min intervals. The
electrocardiogram (ECG) and blood pressure were continuously moni￾tored. Criteria for interrupting the test were severe chest pain, a diag￾nostic ST-segment shift, fatigue, excessive blood pressure increase
(systolic blood pressure ≥ 240 mmHg, diastolic blood
pressure ≥ 120 mmHg), limiting dyspnea, or maximal predicted heart
rate. We also evaluated the maximum rate-pressure product (heart rate x
systolic blood pressure) and exercise time (in min). We performed
echocardiographic imaging from the parasternal long-axis, the short￾axis, the four-chamber view, and the three-chamber views.
2.2. Statistical analyses
We described categorical data by absolute frequency, and continuous
data by mean and standard deviation (SD). To compare the qualitative
and quantitative parameters with ESE diagnosis (ExPH no, ExPH yes),
we used the chi square test and the t-test for independent samples (two￾tailed), respectively. We used the Cohen’s d test to test the effect size
between two means within the groups. An effect size was considered as
large (d = 0.8), medium (d = 0.5), and small (d = 0.2). We set the sta￾tistical significance level at 0.05. We performed all analyses with the
SPSS v.26 statistical software.
3. Results
All patients included in the study had normal chest imaging, normal
pulmonary function studies, no evidence of coronary ischemia and a
normal resting echocardiogram. Out of the 40 patients initially evalu￾ated (for symptoms of exertional dyspnea), 8 were excluded because
fulfilling the criterion of high probability of PH at rest. The mean age of
the remaining 32 participants was 52 ± 12; of those with ExPH it was
45 ± 13.9 years; of those without ExPH 53 ± 1.7. The mean body mass
index (BMI) in patients with ExPH was 27.5 ± 14.7 kg/m2 and
30.1 ± 10.9 kg/m2 for those without PH. Online Table S1 reports the
baseline characteristics, medical history and medication history of the
entire study cohort.
In addition to age, gender and BMI, there were no significant dif￾ferences between the two groups in terms of body surface area (BSA),
heart rate, systolic and diastolic blood pressure, history of hypertension,
comorbidities, cardiovascular risk factors and concomitant medications
(Online Table S1). None of the patients received any specific PAH
treatments.
Three and two patients with ExPH were in WHO-FC III and I,
respectively, while the majority of patients without ExPH were in WHO￾FC I and II (p < 0.001) (Online Table S1), indicating that patients with
ExPH had a worse functional capacity than patients without ExPH.
There were no significant differences between the two groups in terms of
biohumoral data (Online Table S2).
Echocardiography at rest did not show dilatation of the right and left
ventricles either in patients with ExPH and in patients without ExPH
(Table 1). There were no significant differences between the two groups
in terms of left ventricular (LV) function assessed by ejection fraction
(EF), right ventricular (RV) function by FAC and TAPSE, although pa￾tients without ExPH showed a slightly lower E/A ratio indicating LV
diastolic dysfunction (p = 0.046). A significantly higher proportion of
patients with ExPH had higher sPAP and TRV at peak exercise
(p < 0.001), higher right atrial area (p < 0.001) and higher pulmonary
vascular resistance (VTIRVOT, p = 0.003 and ratio of Peak TR velocity to
VTIRVOT, p < 0.001) compared to patients without ExPH (Table 1). We
observed no pericardial effusion in any of the 32 patients.
The extent of ExPH was inversely associated with CD4+ T cell count
(p = 0.047), time to HIV diagnosis (p = 0.014) (Table 2) and time to
beginning of ART (p = 0.041) (Table 3) compared to patients without
ExPH. ExPH and AIDS showed a non-statistically significant trend of
direct association (p = 0.093) (Table 2), although patients with AIDS
had an increase in pulmonary vascular reserve index (PVRI) compared
Coexisting conditions and comorbidities
often affecting HIV people
• viral C and / or B hepatitis, liver
disease, cirrhosis, portal
hypertension
• other coinfections (ie, HHV-8, …)
• intravenous drug use, cocaine
and stimulants abuse
• smoking-related obstructive lung
disease with hypoxemia
• pulmonary embolism (potentially
also caused by intravenous drug
use, HIV-related immune
activation status, …)
Pathogenesis of HIV-associated pulmonary arterial hypertension
WHO group 1
WHO group 3
WHO group 4
Cocaine
Viruses
Chronic inflammation
HIV*
Inflammatory mediators
Pulmonary arterial hypertension
HIV-PAH
Genetic bases
HLA-DR6
HLA-DR52
BMPR2
ALK-1
5-HTT
PH (non-PAH)
hemodynamic
profile
PAH
hemodynamic
profile
Pulmonary vascular remodeling
& disease progression
Inflammation remodeling
HIV viral protein
Tat
gp-120
Nef
• ET-1 secretion
• BMPR2
downregulation
• STAT1 pathway
activation
ART
• IL-1, IL-6,
chemokines
• protease
inhibitors/boosters???
• ET-1 secretion
• immuno-virological control
• ART-associated
dyslipidemias and insulin
reistance
Pulmonary vascular dysfunction
Endothelial cell
dysfunction
NO, PgI2, ET-1
Smooth
muscle cell
dysfunction
Viral load???
*no evidence of HIV direct infections
of pulmonary artery endothelial cells
Fig. 2. Pathogenesis of human immune deficiency virus-related pulmonary artery hypertension. Abbreviations: ALK-1, activin-like kinase type 1; ART, antiretroviral
therapy; BMPR-2, bone morphogenetic protein receptor-2; ET-1, endothelin 1; Gp 120, glycoprotein 120; HHV 8, human herpes virus 8; HIV, human immunode￾ficiency virus; HLA–DR, human leukocyte antigen-D related; 5-HTT, serotonin transporter; IL, interleukine; Nef, negative regulatory factor; NO, nitric oxide; PAH,
pulmonary arterial hypertension; PgI2, prostacyclin 2; Tat, trans activator protein; TNFα, tumor necrosis factor α; WHO, World Health Organization.
R. Madonna et al.
Vascular Pharmacology 139 (2021) 106888
Table 1
Echocardiographic parameters.
Continuous variables No Ex-PH Ex-PH p-value
Average SD Average SD
LVEDD (mm) 43.76 5.31 44.80 7.79 0.712
LVESD (mm) 25.08 4.60 23.80 5.93 0.591
LVEDV (ml) 105.92 31.22 81.80 16.57 0.106
iLVEDV (mL/m2) 37.81 11.23 27.05 6.67
LVESV (ml) 40.19 15.15 23.80 10.03 0.028
iLVESV (mL/m2) 13.98 5.33 9.09 2.05 0.055
LV mass (g) 147.78 41.46 126.50 58.36 0.332
iLV mass (g/m2) 78.13 27.47 69.50 29.30 0.529
LAD (mm) 49.71 7.88 39.00 21.05 0.050
LAV (mm) 35.82 19.20 40.46 25.40 0.641
iLAV (mL/m2) 12.57 7.06 15.41 6.86 0.415
LVEF (%) 65.91 7.86 65.20 6.22 0.850
FwSVLVOT (mL) 72.26 27.91 68.80 7.56 0.788
iFwSV (ml/m2) 25.26 9.85 23.61 2.91 0.717
E wave (cm/s) 68.29 19.48 81.68 7.99 0.146
A wave (cm/s) 70.68 32.63 66.10 40.75 0.784
Septal e wave (cm/s) 9.58 3.14 9.40 0.38 0.900
E/A 1.07 0.40 1.55 0.76 0.046
E/e 6.80 3.65 8.72 0.89 0.257
iRVESA (cm2/m2) 3.75 1.62 5.07 2.82 0.150
iRVEDA (cm2/m2) 6.50 1.82 5.69 3.02 0.419
iRVESV (ml/m2) 6.19 2.95 10.01 10.52 0.112
iRVEDV (ml/m2) 14.21 5.33 15.81 12.90 0.638
RD1 (mm) 35.62 8.22 36.80 5.12 0.761
RD2 (mm) 33.43 6.24 31.20 7.01 0.479
RD3 (mm) 19.89 7.16 16.80 5.02 0.367
RVOT prox (mm) 30.90 6.03 32.40 4.67 0.604
RVOT dist (mm) 31.34 7.60 32.40 10.60 0.790
Eccentricity index 3.56 9.11 0.89 0.06 0.525
Right ventricle/left ventricle basal diameter ratio 0.88 0.17 0.87 0.18 0.880
TAPSE (mm) 21.01 8.59 26.00 3.08 0.215
FAC (%) 43.33 9.52 47.20 9.83 0.415
RV E/A 4.96 14.76 0.54 0.12 0.515
RV E/e’ 3.84 1.99 3.10 1.11 0.478
RV S vel (cm/s) 10.88 3.44 7.14 0.93 0.024
RV S VTI (cm2) 2.68 2.64 1.21 0.31 0.231
sPAP (mmHg) 21.73 8.47 26.00 7.35 0.302
sPAP at exercise peak (mmHg) 29.96 8.14 50.66 3.70 <0.001
mPAP (mmHg) 16.40 4.18 17.93 4.59 0.465
TR velocity (m/s) 2.03 0.42 2.20 0.49 0.413
TR velocity at exercise peak (m/s) 2.44 0.45 3.40 0.07 <0.001
Right ventricular outflow doppler acceleration time (msec) 108.54 32.69 132.20 30.96 0.146
IVC diameter (mm) 14.62 4.94 12.86 6.75 0.496
Right atrial area (cm2) 13.49 2.06 17.98 3.12 <0.001
iRAV (ml/m2) 4.70 0.75 7.24 1.31 <0.001
VTIRVOT (cm2) 15.88 3.96 10.02 1.02 0.003
TRV/VTIRVOT 0.13 0.04 0.22 0.05 <0.001
Categorical variables Frequency Frequency p-value
Concentric remodeling no 19 4 0.999
si 7 1
Normal geomtery no 11 2 0.999
si 15 3
Concentric hypertophy no 23 5 0.999
si 3 0
Mitral regurgitation no 12 4 0.324
Trivial 8 1
mild 6 0
moderate 0 0
severe 0 0
Aortic regurgitation no 21 5 0.766
Trivial 2 0
mild 2 0
moderate 1 0
severe 0 0
Tricuspid regurgitation no 1 1 0.395
Trivial 14 2
mild 11 2
moderate 0 0
severe 0 0
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Vascular Pharmacology 139 (2021) 106888
to patients without ExPH (ratio of Peak TR velocity to VTIRVOT,
p = 0.020) at rest TTE (Table 4). We also observed an inverse correlation
between the time to beginning of ART with right atrium area (r = −
0.411, p = 0.022) and indexed right atrial volume (r = − 0.102,
p = 0.009) (Table 5).
Finally, current use of protease inhibitors showed a non-statistically
significant association with ExPH (p = 0.060). No associations with
coinfections, liver disease, drug consumption, ART discontinuation or
development of resistance to ART were found, likely because of the
exiguity of the sample.
4. Discussion
In the present study we investigated the existence of an association
between ExPH, assessed by ESE, and both clinical and immuno￾virological status in HIV patients with low or intermediate probability
of PH at resting TTE. In our cohort, we found ExPH in 22% of patients
with low or intermediate probability of PH. This high prevalence is
consistent with that previously shown in patients with scleroderma [12]
and other connective tissue diseases [22]. Moreover, as previously re￾ported in patients with scleroderma by our group and others [8,9], we
found that the presence of ExPH is associated with a higher WHO-FC
functional class compared to the absence of ExPH, indicating a worse
functional capacity in patients with ExPH. More importantly, we found
that patients with ExPH have a poorer immunological control of HIV
Cohen D index
iLVESV (mL/m2) 1.13
E wave (cm/s) 0.73
iRVESA (cm2/m2) 0.72
iRVESV (ml/m2) 0.80
Right ventricular outflow doppler acceleration time (msec) 0.73
LVEDD, left ventricle end-diastolic diameter; LVESD, left ventricle end-systolic diameter; LVEDV, left ventricle end-diastolic volume; LVESV, leftventricle end-sistolic
volume; iLVEDV, indexed LVEDV; iLVESV, indexed LVESV; LAD, left atrial diameter; LAV, left atrial volume; iLAV, indexed LAV; LVEF, left ventricle ejection fraction;
FwSVLVOT, forward stroke volume at left ventricle outflow; iFwSV, indexed FwSV; iRVESA, indexed right ventricle end-sistolic area; iRVEDA, indexed right ventricle
end-diastolic area; iRVESV, indexed right ventricle end-sistolic volume; iRVEDV, indexed right ventricleend-diastolic volume; RD, right diameter; RVOT, right
ventricle outflow; TAPSE, tricuspid annular plane excursion; FAC, fractional area change; VTI, velocity time integral; sPAP, sistolic pulmonary arterial pressure; mPAP,
mean PAP; TR, tricuspid regurgitation; IVC, inferior vena cava, iRAV, indexed right atrial volume; TRV, tricuspid regurgitation velocity; Ex-PH, exercise pulmonary
hypertension. Bold indicates the p value < 0.05.
Table 2
Infectious disease data.
Continuous variables No Ex-PH Ex-PH p-value
Average SD Average SD
time to HIV diagnosis (years) 18.9 22.7 5.8 5.1 0.014
CD4+ T cell count (%) 33.6 10.2 23.7 6.5 0.047
Categorical variables Frequency Frequency p￾value
AIDS No 21 2 0.093
Yes 5 3
Development of resistance
to ART
No 17 3 0.999
Yes 9 2
HIV RNA levels (copies/mL) <20 copies/
ml
19 2 0.296
>20 copies/
ml
7 3
Coinfections No 7 1 0.999
Yes 19 4
Liver disease No 23 5 0.999
Yes 3 0
Previous drug addiction No 18 4 0.561
Yes 5 0
Ex-PH, exercise pulmonary hypertension; HIV, Human immunodeficiency virus;
ART, antiretroviral therapy. Bold indicates the p value < 0.05.
Table 3
HIV therapy.
Continuous variables no Ex-PH Ex-PH p-value
Average SD Average SD
Time to onset of ART 12.2 8.8 5.6 4.9 0.041
Categorical variables Frequency Frequency p￾value
Current use of protease
inhibitors
No 25 3 0.060
Yes 1 2
Combination of ART with
boosters
No 22 4 0.999
Yes 4 1
Virological response to
ART
Poor 1 1 0.287
Good but not
optimal
7 2
Optimal 18 2
ART discontinuation No 15 4 0.624
Yes 11 1
Legend; Ex-PH, exercise pulmonary hypertension; ART, antiretroviral therapy.
This is not part of the figure caption
Table 4
Echocardiographic variables.
AIDS Average SD p-value
Right atrial area (cm2) no 13.800 2.307 0.159
yes 15.413 3.719
iRAV (ml/m2) no 4.906 0.989 0.124
yes 5.708 1.797
TRV/VTIRVOT no 0.131 0.046 0.020
yes 0.180 0.054
Cohen D index
Right atrial area (cm2) − 0.594
iRAV (ml/m2) − 0.650
AIDS, Acquired Immunodeficiency Syndrome; iRAV, indexed right atrial vol￾ume; TRV, tricuspid regurgitation velocity; VTI, velocity time integral; RVOT,
right ventricle outflow. This is not part of the figure caption
Table 5
Echocardiographic variables.
Satistic analysis Time to onset of ART
Right atrial area (cm2) r di Pearson − 0.411
p-value 0.022
iRAV (ml/m2) r di Pearson − 0.463
p-value 0.009
VRT/VTIRVOT r di Pearson − 0.102
p-value 0.587
iRAV, indexed right atrial volume; TRV, tricuspid regurgitation velocity; VTI,
velocity time integral; RVOT, right ventricle outflow; ART, antiretroviral
therapy.
R. Madonna et al.
Vascular Pharmacology 139 (2021) 106888
infection, as they had significantly lower CD4+ T cell count. Finally,
patients without ExPH had a longer time to HIV diagnosis and a longer
time to beginning of ART than patients with ExPH. Our findings suggest
that patients with a long-standing diagnosis who are on adequate ART
and with a good immunological response are at a lower risk of devel￾oping ExPH than those with poor immunological control, albeit with a
more recent diagnosis. This interpretation is further supported by the
fact that patients in long-standing ART show lower right atrium area and
indexed right atrial volume. Moreover, we also observed a trend
(p = 0.093) for an association between ExPH and AIDS diagnosis, which
was not significant likely because of the small size of our cohort, which
included a low number of AIDS patients. However, AIDS patients
showed a significant increase in pulmonary vascular resistance
compared to those without an AIDS diagnosis, supporting our hypoth￾esis that poor immunological control is a major risk factor for the
development of ExPH. This is consistent with previous studies high￾lighting the role of immuno-virological status in the development and
prognosis of HIV-related PAH [7,23,24]. Thus, our results suggest that
assessment of ExPH by ESE may help identify subgroups of HIV patients
with a propensity to develop subclinical impairment of pulmonary cir￾culation following poorer control of HIV infection. As PH is recognized
as a complication of HIV leading to increasing mortality, the develop￾ment of isolated ExPH can be considered an early marker of worsened
prognosis in HIV patients at risk of developing PAH.
However, in contrast to previous data by Quezada et al. pointing to
the protective role of undetectable HIV-RNA [23], we found that the
proportion of patients with suppressed HIV-RNA viral load was similar
between the two groups, implying that the role of HIV in the patho￾genesis of pulmonary vascular disease is unrelated to the viral load or
direct endothelial cell infection.
In fact, while there is no evidence that HIV directly infects pulmo￾nary artery endothelial cells, and HIV nucleic acids are not found in
pulmonary vessels of human lung tissues [24], HIV viral proteins (ie, gp
120, Nef and Tat) are known to be noxious to endothelial cells pro￾moting apoptosis, growth and proliferation both directly and indirectly
through interactions with molecular partners of the infected host
[25–29]. Thus, the increased incidence of PAH in HIV patients might be
the result of an indirect role of the virus, stimulating the host to release
proinflammatory cytokines or growth factors which would result in
PAH, in presence of individual susceptibility to the development of this
disease (Fig. 2).
HIV proteins can also contribute to the development of PAH by
triggering a systemic and chronic inflammatory response (Fig. 2). High
levels of circulating cytokines and soluble mediators, namely interleukin
6 (IL-6), tumor necrosis factor α (TNFα) and nitric oxide (NO) synthase
inhibitors [4,30] have been found in HIV patients with PAH, which
likely promote fatigue and dyspnea. Therefore, measuring the blood
levels of these mediators can be a useful element in stratifying patients’
risk of HIV-related PAH. We are now conducting a parallel study in this
group of patients, where we are analyzing the existence of possible as￾sociations between ExPH and levels of proinflammatory biomarkers,
including IL-6.
In our cohort, we also observed a non-significant trend of association
between current use of protease inhibitors and the risk of ExPH, which
seems to be unrelated to combination with boosters. Previous work
suggested that patients currently treated with protease inhibitors had an
increased risk of PAH [4,31], probably inducing endothelial myth￾ocondrial dysfunction and stimulating endothelin release [32,33], but,
to our knowledge, no other studies confirmed these data. In our popu￾lation, however, only a few patients were currently being treated with
protease inhibitors, making this association difficult to assess. Further
investigation is required to establish the role of protease inhibitors and
other antiretroviral drugs in the development of PAH.
As for other host risk factors, and in contrast with previous evidence
[23,34,35], we found no significant association between ExPH and
intravenous drug use, coinfections or liver disease. It is worth pointing
out that, in view of the small number of patients in our cohort, all
relevant coinfections were grouped together, including HBV, HCV,
syphilis and human herpes virus (HHV) 8. In the future, a larger sample
size would probably allow us to better assess the potential role of these
factors.
Finally, some kind of genetic susceptibility is likely, as only a small
percentage of HIV-infected patients develops PAH, while viral factors
and viral-host interaction are always present after infection. Further
investigation into the identification of genes potentially involved in the
propensity to develop ExPH [i.e., human leukocyte antigen (HLA) class
II DR52 and DR6 [36], members of the transforming growth factor beta
family BMPR2 [37], activin-like kinase (ALK) type 1 [38], and poly￾morphisms of the serotonin transporter (5-HTT) gene promoter [39]] is
needed (Fig. 2).
4.1. Study limitations
We recognize several limitations in our study. Firstly, the sample size
is small, mainly because it was challenging to identify subjects with HIV
and unexplained dyspnea who met all the enrollment criteria. Secondly,
our study included the evaluation of pulmonary hemodynamics without
right heart catheterization. The non-invasive evaluation of PH during
exercise can be difficult, as it can be hindered by various technical
factors. However, invasive testing for the assessment of PH in such early￾stage or normal patients would be either ethically impossible or highly
impractical. Finally, this is a horizontal study, assessing associations and
– for the moment – without a long term follow-up. Therefore, progres￾sion to resting PH is at the moment purely hypothetical. We are
currently performing a larger study with a long-term follow-up, which
will best clarify the prognosis and progression of ExPH in the HIV
population.
In conclusion, ExPH is associated with a poorer clinical status and
immunological control in HIV patients. The assessment of ExPH by ESE
may help identify subgroups of HIV patients with a propensity to
develop subclinical impairment of pulmonary circulation, thus
contributing to a better risk stratification of such patients.
Supplementary data to this article can be found online at
Declaration of competing interest
The authors declare no conflict of interest.
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