In a focused study led by researchers in Japan and published online in late 2025, a striking 44% of people with systemic sclerosis (SSc) who report exercise intolerance showed exercise-induced pulmonary hypertension (PH). Even more notable, about 30% of the same group had PH at rest. The study also found that nailfold capillary density—an accessible skin-based measure—was notably lower among those with PH and exercise-induced PH, offering a potential early clue for clinicians. The researchers emphasize that a small set of clinical features during exertion, together with a simple nailfold capillary assessment, might help identify patients at risk who would benefit from more definitive testing, such as exercise right heart catheterization.
The research was conducted as a single-center retrospective observational study spanning April 2022 to April 2024 and included 50 SSc patients who reported exercise intolerance. All participants underwent resting right heart catheterization to diagnose PH, and those without resting PH were offered exercise right heart catheterization to determine exercise-induced PH. In addition to standard cardiopulmonary assessments, nailfold videocapillaroscopy was used to quantify capillary density in the central nailfold of the fingers. This technique, which examines tiny capillaries beneath the fingernails, is already used in rheumatology clinics to characterize microvascular changes in SSc. The investigators then compared the features of three groups: PH at rest, exercise-induced PH, and non-PH.
Key findings are both provocative and clinically actionable. First, nearly half of the patients with SSc and exercise intolerance met criteria for exercise-induced PH, underscoring that abnormal pulmonary vascular responses during physical activity are perhaps more common than resting measurements alone would suggest. This is important because many SSc patients experience symptoms such as fatigue, breathlessness during daily activities, or palpitations that may not be fully explained by resting testing. The study’s authors argue that exercise-induced PH could represent an early stage in a spectrum that may progress to overt pulmonary arterial hypertension (PAH) or complicate heart function, particularly if heart failure with preserved ejection fraction (HFpEF) emerges as a common comorbidity.
A striking association emerged between nailfold capillary density and exercise-induced PH. Using a threshold of seven capillaries per millimeter, a substantial majority of patients with exercise-induced PH fell below this threshold. In multivariate analyses, two factors stood out as robust predictors: exertional palpitations and nailfold capillary density of seven or fewer capillaries per millimeter. Palpitations during exertion are not a classic standalone warning sign for PH, but when they occur alongside reduced nailfold density and exertional dyspnea, they seem to strongly flag patients who may benefit from invasive hemodynamic testing during exercise. In practical terms, clinicians may consider exercise RHC for patients who present with this triad, even if resting measurements look relatively reassuring.
In terms of risk stratification, the study found that HFpEF prediction scores increased with disease progression. A remarkable 68.2% of those with exercise-induced PH and 93.3% of those with resting PH met the HFpEF criteria, suggesting that diastolic dysfunction and ventricular-arterial coupling play major roles in the hemodynamic picture of SSc patients as they age or accumulate vascular and myocardial involvement. The overlap between PH and HFpEF may complicate management, but it also points to shared pathways—microvascular dysfunction, myocardial stiffening, and impaired vascular reserve—that warrant integrated therapeutic approaches.
From a clinical practice perspective, the authors stress that the triad of exertional dyspnea, exertional palpitations, and decreased nailfold capillary density can serve as a practical, expedient screen in daily clinics. They emphasize that palpitations alone are not diagnostic of PH, but in the right clinical context, they can prompt timely referral for confirmatory testing. The beauty of this approach lies in its simplicity: while resting tests are essential, adding targeted functional assessment and a skin-based microvascular evaluation could speed up identification of patients at risk, allowing earlier intervention and closer monitoring.
The study raises several important implications for Thai clinicians and patients. Systemic sclerosis, though relatively rare, does present among Thai populations, and many rheumatology and cardiopulmonary clinics must balance high patient loads with the need for thorough cardiovascular screening. Resting tests—such as echocardiography and standard pulmonary function tests—are widely available in urban centers, but access to invasive testing like right heart catheterization is more variable, particularly in regional hospitals. The researchers’ emphasis on simple, repeatable indicators that can trigger further evaluation is especially relevant for Thailand, where primary care and specialty clinics increasingly collaborate to triage patients who require advanced investigations.
For Thai readers, the study’s practical takeaways are clear. First, clinicians should remain vigilant for exertional symptoms—even when resting measurements seem normal. In SSc patients who experience breathlessness with activity, clinicians might consider additional screening steps, including nailfold capillaroscopy when available. If the nailfold density is low, and exertional dyspnea is accompanied by palpitations, referral for exercise hemodynamics testing should be contemplated. While not all clinics can offer exercise RHC, identifying high-risk patients early can facilitate timely referrals to tertiary centers where definitive testing and management planning can occur.
From a Thai cultural and health-system perspective, several themes emerge. Families often participate actively in healthcare decisions, especially for chronic illnesses like SSc that require long-term management and multiple specialist referrals. In this context, educating patients and their families about the signs that warrant more intensive cardiovascular evaluation can empower timely action, reduce uncertainty, and potentially improve outcomes. In Buddhist-influenced communities, compassionate care and transparent communication about prognosis and treatment options align with values of alleviating suffering and respecting patient autonomy. Clinicians who can articulate the rationale for additional testing in culturally sensitive ways are likely to gain trust and support from patients and families.
The research has clear limitations that Thai readers should understand as well. The study involved only 50 participants and came from a single center, which means the findings must be interpreted with caution and confirmed in larger, multi-center cohorts. The retrospective design also limits causal inferences about how exercise-induced PH develops over time or progresses to resting PH or HFpEF. The study did not comprehensively evaluate all potential pulmonary comorbidities, and follow-up data on disease progression were not captured. Financial disclosures among some authors, while common in medical research, remind readers to consider potential biases when weighing study conclusions. Despite these caveats, the study contributes valuable real-world observations that can inform clinical thinking and future research.
What does this mean for the future of health policy and clinical practice in Thailand? The study’s emphasis on actionable, low-cost indicators could shape screening guidelines for SSc in Thai settings. Nailfold videocapillaroscopy is already a routine tool in many rheumatology clinics, and its integration with targeted functional assessments could be a pragmatic way to stratify risk. Training rheumatologists and cardiologists to recognize the significance of exertional symptoms and capillary density could lead to earlier referrals for exercise testing and, when indicated, invasive hemodynamic assessment. Policymakers and hospital administrators may consider investing in capacity-building for exercise testing, CPET, and exercise RHC, as well as standardized protocols that link microvascular findings with cardiopulmonary risk in systemic sclerosis.
Looking ahead, larger, multicenter studies are needed to validate these findings in diverse populations, including Thai cohorts. Research should explore the natural history of exercise-induced PH in SSc, its progression trajectory, and the impact of early detection on clinical outcomes such as hospitalization, quality of life, and survival. Cost-effectiveness analyses will be essential for informing national guidelines and reimbursement policies. In the meantime, Thai clinicians can begin translating these insights into practice by heightening awareness, refining referrals, and integrating nailfold capillaroscopy and exertional assessments into routine care for patients with systemic sclerosis who report exercise limitations.
In the Thai healthcare setting, these findings offer a practical path toward earlier identification of a potentially reversible or modifiable condition. By weaving together clinical signs from daily life, a simple nailfold microvascular test, and judicious use of exercise-based hemodynamics testing, physicians may help patients navigate toward timely therapy and better long-term outcomes. For patients and families, recognizing that exercise intolerance could reflect more than simple fatigue—and that specialized testing can clarify the situation—may empower them to seek appropriate care without delay. For communities, universities, and hospitals, this study underscores the value of combining accessible bedside tools with targeted, higher-level diagnostics to improve care for systemic sclerosis and its cardiovascular complications.