Our study examined ambulatory and hospitalized patients who underwent RHC between 2005 and 2016 at Massachusetts General Hospital. If an individual underwent multiple RHC procedures during this period, only the initial RHC was included for analysis. A total of 10,306 cases were included. Cases were excluded if they met the following clinical exclusion criteria: acute myocardial infarction (MI) occurring on the same day as catheterization, cardiac arrest or shock within 24 hours, presence of mechanical ventilation, presence of intra-aortic balloon pump, history of heart or lung transplant, complicated adult congenital heart disease, history of valvular replacement, or those on dialysis (n = 887). Cases were also excluded if there were missing key clinical covariates (n = 484), patient identifier variables (n = 398), or hemodynamic parameters (n = 252), which led to a final study sample of 8,285 cases. This study was approved by the appropriate Institutional Review Board.

The following clinical characteristics were extracted from the medical record at the time of RHC: age, sex, body mass index (BMI), smoking status, and presence of comorbidities (diabetes mellitus, hypertension, history of MI, history of heart failure (HF), prior lung disease, and chronic kidney disease). Obstructive sleep apnea (OSA) was ascertained from the electronic medical record utilizing International Classification of Diseases Ninth Revision ( ICD‐9 ) or Tenth Revision ( ICD‐10 ) codes.

Hemodynamic measures were recorded directly from the time of RHC, including resting blood pressure, heart rate, mean right atrial (RA) pressure, pulmonary artery (PA) systolic and diastolic pressure, transpulmonary gradient (TPG), and mean pulmonary capillary wedge pressure (PCWP). Any nonphysiologic parameters were set to missing. The PA pulsatility index (PAPi) was calculated as P A s y s t o l i c − P A d i a s t o l i c p r e s s u r e R A p r e s s u r e . If RA pressure was recorded as zero, the value was set to one to allow for PAPi calculation. If RA pressure was recorded as negative, this was deemed nonphysiologic and set to missing, which affected <1% of measurements. Cardiac output and index measurements were obtained via thermodilution methods whenever possible. If not available, assumed Fick cardiac output and index were used. Both were indexed using the Mosteller formula for body surface area. Right ventricular stroke work index (RVSWI) was calculated as 0.0136 x stroke volume index x (Mean PA pressure-mean RA pressure) , where stroke volume index was calculated by dividing cardiac index by heart rate.

PH was defined as mean PA pressure (mPAP) > 20 mmHg based on the 2022 European Society of Cardiology/European Respiratory Society guidelines. We further categorized PH into three hemodynamic subtypes: precapillary PH (TPG > 12 mm Hg and PCWP ≤ 15 mm Hg), postcapillary PH (TPG ≤ 12 mm Hg and PCWP > 15 mm Hg), and mixed PH (TPG > 12 mm Hg and PCWP > 15 mm Hg). We utilized TPG cutpoints rather than pulmonary vascular resistance (PVR) as not all participants had available cardiac output. For those with cardiac output data, we examined PH hemodynamic subtypes using PVR instead of TPG in secondary analyses.

The distribution of PAPi was winsorized to limit effect of outliers on the analysis, setting the minimum at 0.3 and the maximum at 30 (2 patients had PAPi < 0.3, and 51 patients had PAPi > 30 prior to winsorizing). Baseline characteristics among those with PH were summarized across the total sample by sex. Sex differences in prevalence of PH and PH subtypes were examined using Chi squared tests. We examined cross-sectional associations of sex with hemodynamic indices of RV function among those with PH, including PAPi, RVSWI, and RA:PCWP ratio using multivariable linear regression. Models were adjusted for the following clinical covariates: age, BMI, hypertension, diabetes mellitus, OSA, chronic lung disease, prevalent MI, prevalent HF, chronic kidney disease.

We next constructed multivariable Cox models to examine the association of sex with outcomes, adjusting for covariates as above. In secondary models, we stratified by PH hemodynamic subtype. In exploratory analyses, we evaluated whether sex modified the association of RV function with adverse outcomes among those with PH using multiplicative interaction terms (sex*PAPi, sex*RVSWI, and sex*RA:PCWP ratio). Analyses were conducted using SAS software, Version 9.4 (Cary, NC).

Among 8,285 individuals who underwent (RHC) between 2005 and 2016, 5,208 (63%) met criteria for PH, as defined by a mPAP >20 mmHg. There was no significant sex difference in the prevalence of overall PH, with 2,032 (62%) women and 3,176 (63%) men meeting PH criteria (p = 0.96, baseline characteristics in Supplemental Table 1 ).

Among individuals with PH, average age was 64 ± 12 years and 39% were women. Men were significantly more likely to have comorbid conditions including previous MI, previous HF, hypertension, diabetes mellitus, hypercholesteremia, and OSA (p <0.001 for all). However, women were more likely to have chronic lung disease (20.2% vs 16.7%, p <0.001). Additional baseline characteristics of individuals with PH are shown in Table 1 .

We found that hemodynamic PH subtypes significantly differed by sex, with women more likely to have precapillary PH and men more likely to have postcapillary PH ( Figure 1 ). Specifically, 31% of women versus 22% of men had precapillary PH (p <0.001), 39% versus 51% had postcapillary PH (p <0.001), and 30% versus 27% had mixed PH (p = 0.03).

Prevalence of hemodynamic PH subtypes in women (red) and men (blue). Among women with PH, 31% (n = 544) had precapillary PH, 39% had postcapillary PH (n = 685), and 30% had mixed (n = 527). Among men with PH, 22% (n = 605) had precapillary PH, 51% had postcapillary PH (n = 1,402), and 27% had mixed (n = 743). Note that total individuals of PH in our study was 5,208 (vs 4,506 noted here); individuals who did not meet criteria for either precapillary, postcapillary, or mixed PH were excluded in assessing prevalence of subtypes. (PH = pulmonary hypertension).

Stay updated, free articles. Join our Telegram channel

Join