Cifci, Gizem

Abstract Background Catheter ablation for atrial fibrillation (AF) improves quality of life and lowers cardiovascular adverse events. However, AF recurrence rates remain high - thus the need for better or improved predictors of AF recurrence. The role of left atrial (LA) stiffness remains unclear, as prior findings were controversial. Purpose To explore the relationship between a noninvasive LA stiffness index (LAstiffn) and AF recurrence after catheter ablation. Methods We analyzed a prospectively recruited cohort of patients who underwent catheter ablation for AF, were in sinus rhythm at 3 months post-ablation, had no significant (< moderate) valvular disease, and had LA volumes and LA diastolic function prospectively measured. LAStiffn was calculated as (E/e’)/LA emptying fraction (LAEF) ratio (abnormal defined as >15/45≈0.3). Outcome endpoint was the first documented AF/atrial flutter episode, lasting >30s, beyond 3 months post ablation (end of blanking period). Results A total of 589 patients were studied (mean age 60±10 years; 75% men; 50% with persistent AF; Table 1). At 3 months post-ablation, mean LAVI(Left atrial volume index) was 36±10 mL/m2 and LAstiffn 0.32±0.22. LAstiffn tended to be higher in older patients, in females, and patients with persistent AF and comorbidities (hypertension, congestive heart failure, coronary artery disease, CHA2DS2-VASc score ≥2, etc). At multivariable regression analysis, LAstiffn correlated with LV size and mass, degree of mitral/tricuspid regurgitation, and right ventricular systolic pressure. At 1 year, 3 years, and 8 years follow up, AF recurred in 118, 191, and 347 patients, respectively. At univariate Cox proportional hazards regression analysis, LAstiffn index >0.3 was significantly associated with AF recurrence at 1 year (log-rank P=.0005), 3 years (P=.0002), and 8 years follow up (P<.0001; Figure). In multivariate analysis including all clinical and laboratory factors with P<.10 in univariate analysis, LAstiffn >0.3 remained an independent factor for AF recurrence only at 3-years (adjusted HR 1.40 [1.03-1.91], P=.03) and 8 years follow up (adjusted HR 1.65 [1.29-2.13], P<.0001) after adjustment for age, sex, type of AF (persistent/paroxysmal), LA volume index (LAVi), obstructive sleep apnea, and prior pacemaker/ICD implantation (best independent factors); P=.14 at 1 year follow up. In ROC analysis, LAstiffn (AUC 0.61, P=.001) performed slightly better than LA deformation LAEF (AUC 0.59, P=.002) or E/e’ (AUC 0.58, P=.03), though with modest sensitivity/specificity (58%/62%). Conclusions LAstiffn may reflect LA myopathy that is likely due to the cumulative effects of comorbidities, diastolic dysfunction, and intrinsic LA tissue remodeling. LA stiffening may be a substrate facilitating redevelopment of AF, thus patients with increased LAstiffn may need more frequent monitoring to prevent/treat AF recurrence earlier.

Introduction: An elevated blood pressure (mean arterial pressure, MAP) response to exercise is an independent predictor of hypertension (HTN) development. HTN is highly prevalent in postmenopausal females. Postmenopausal, compared to premenopausal, females have a higher MAP at rest and during exercise primarily due to higher systemic vascular resistance (SVR). Studies using small muscle mass exercise have suggested that postmenopausal females have augmented increases in MAP from rest to exercise. However, it is unclear if postmenopausal females have augmented MAP responses from rest to exercise during whole-body exercise. Hypothesis: We hypothesized that postmenopausal females would have greater increases in MAP and smaller decreases in SVR from rest to peak exercise than premenopausal females. Methods: Normotensive premenopausal (n=16; age: 30±7 yrs; BMI: 23±4 kg/m 2 ) and postmenopausal (n=14; age: 57±7 yrs; BMI: 27±4 kg/m 2 ) female participants performed an incremental cycling test until task failure. Blood pressure was measured by manual sphygmomanometry, cardiac output (Q) via open-circuit acetylene wash-in technique, and SVR was calculated. Data are reported at rest and peak oxygen uptake (VO 2 ). Data are also reported as % change from rest to VO 2 peak. Results: Postmenopausal females had higher MAP and SVR at rest and at VO 2 peak than premenopausal females (all, p<0.05). Postmenopausal, compared to premenopausal, females had lower Q at VO 2 peak commensurate with the lower achieved VO 2 peak (p<0.01). Resting MAP was positively related to MAP at VO 2 peak in postmenopausal females (r=0.85, p<0.01), but not premenopausal females (p=0.22). % change in MAP from rest to VO 2 peak was not different between groups (Post: 18±8 vs. Pre: 18±9%) (p=0.94). However, postmenopausal females had smaller % decreases in SVR from rest to VO 2 peak (Post: -44±7 vs. Pre: -54±8%) and smaller % increases in Q compared to premenopausal females (Post: 113±31 vs. Pre: 162±50%) (both, p<0.01). Conclusion: Our findings indicate that postmenopausal and premenopausal females have similar increases in MAP from rest to VO 2 peak; however, the mechanisms contributing to the MAP response differed by menopausal status. Postmenopausal females relied on smaller decreases in SVR, whereas premenopausal females had greater increases in Q. These findings provide important insight into the mechanisms contributing to the clinically relevant higher MAP response during exercise in postmenopausal females.

Study objective: Heart failure (HF) syndrome is associated with pulmonary system abnormalities that have a direct impact on mortality. Heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF) are distinct subtypes of HF with different pathophysiologies, clinical presentations, and treatment approaches. Obesity is highly prevalent in HFpEF and significantly contributes to its development. Importantly, obesity and high abdominal adiposity can have significant effects on pulmonary function. Therefore, HFpEF patients may have more pronounced pulmonary function impairment than HFrEF patients in part due to higher prevalence of upper body adiposity. Hypothesis: We hypothesized that lung volumes would be lower in patients with HFpEF compared to those with HFrEF and CTL. Further, we hypothesized that higher upper body adiposity (measured as trunk fat by dual-energy X-ray absorptiometry) would be associated with lower lung volumes in patients with HFpEF. Methods: HFpEF patients (n=26), HFrEF patients (n=26) and CTL (n=36) performed pulmonary function tests according to ATS/ERS guidelines. Total lung capacity (TLC), residual volume (RV), forced vital capacity (FVC), and forced expiratory volume in one second (FEV1) were measured and absolute and % predicted values are reported. Dual-energy X-ray absorptiometry scans quantified % trunk fat. Absolute lung volumes were compared across groups using ANCOVA with age as a covariate and % predicted lung volumes were compared using one-way ANOVA. Results: HFpEF patients were older than HFrEF patients and CTL (HFpEF: 71±9 vs. HFrEF: 65±9 vs. CTL: 63±11 yrs, both p<0.05) while no differences were present among groups for sex, height, or BMI (all, p>0.05). HFpEF patients had higher % trunk fat than CTL (p<0.01), while no differences were present between HFrEF and HFpEF or CTL (p>0.05) (HFpEF: 46±11 vs. HFrEF: 42±8 vs. CTL: 38±11%). HFpEF patients had lower FVC (HFpEF: 3.0±0.7 vs. HFrEF: 3.7±1.0 vs. CTL: 3.8±0.8 L), FEV1 (HFpEF: 2.3±0.5 vs. HFrEF: 2.8±0.8 vs. CTL: 2.9±0.6 L), TLC (HFpEF: 5.5±1.3 vs. HFrEF: 6.3±1.4 vs. CTL: 6.4±1.1 L), and % predicted TLC than CTL (all, p<0.05). HFpEF and HFrEF patients had lower % predicted FVC and % predicted FEV1 than CTL (p<0.05). All other pulmonary function parameters were not different among groups (p>0.05). There was a negative relationship between % trunk fat and TLC for HFpEF patients (r= -0.51, p<0.05). There were negative relationships between % trunk fat and FVC for CTL (r= -0.37) and HFpEF patients (r= -0.50) (both, p<0.05), with statistically different y-intercepts (p<0.01). There were no other significant relationships (all, p>0.05). Conclusion: These findings demonstrate that patients with HF have smaller lung volumes than CTL. Further, our findings suggest that upper body adiposity may be an important contributing factor to these pulmonary system abnormalities in HFpEF. None. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract Background Atrial fibrillation (AF) occurs more frequently in men, but women suffer more AF recurrence; mechanisms are not completely understood. Purpose To explore whether sex related differences in LA stiffness (LAstiffn) in patients with AF ablation could potentially explain differences in AF recurrence. Methods We screened patients with catheter ablation for AF, in sinus rhythm at 3 months post-ablation, with no significant mitral valve disease (&lt; moderate), and with prospectively measured LA volumes [maximum (LAVI) and minimum volume index] by echocardiography. LAStiffn index was estimated as (E/e’)/LA emptying fraction. Outcome endpoint was AF recurrence up to 14 years post ablation. Results A total of 591 patients with AF ablation were studied (mean age 60±10 years; 25% women; Table1). At 3 months post-ablation, LAVI was 36±10 mL/m2 and LAstiffn was 0.31±0.21 1/%. Compared to males, female patients were slightly older, had more frequently hypertension, congestive heart failure, prior stroke/TIA, higher CHA2DS2-VASc score; they less often had persistent AF, coronary artery disease, or dilated cardiomyopathy. Women also had higher LAstiffn (0.37±0.24 vs. 0.29±0.19, P &lt;.0001, Figure 1), despite similar indexed LA volumes (Table1). Rates of AF recurrence at follow-up (median 7.5 years; 347 patients with events) were higher in women vs. men (Figure 2, left; log-rank P&lt;.001) and persisted after adjustment for age, type and duration of AF, body mass index, cardiovascular risk factors and comorbidities, CHA2DS2-VASc score ≥2, LV ejection fraction, and LAVI (adjusted HR 1.58 [1.20-2.08], P=.001). Overall, LA volumes and LAstiffn were higher in patients with older age and more comorbidities (hypertension, congestive heart failure, coronary artery disease, persistent AF, CHA2DS2-VASc score ≥2, etc; P&lt;.01 for all). At multivariable regression analysis, LAVI and LAstiffn correlated with E/e’, LV size and mass, degree of mitral/tricuspid regurgitation, and LV stroke volume index (only LAVI). In addition, LAstiffn was higher in patients with elevated right ventricular systolic pressure (RVSP) &gt;35 mmHg and increase in RVSP more than 10 mmHg from pre-ablation (P&lt;.0001) (correlation R=0.44, P&lt;.0001). At follow-up, after adjusting for age and LAVI, higher LAstiffn remained associated with AF recurrence in women (P=.02, HR 2.82 per unit change, 95% CI, 1.08-6.72; Figure 2, right), but not in men (P=.30). Conclusions LAStiffn is higher in women vs. men and correlates with burden of comorbidities, aging, diastolic dysfunction and pulmonary hypertension, possibly reflecting more extensive LA myopathy, and potentially contributing to sex differences in AF recurrence.Figure 1Table 1

Introduction: Obesity and hypertension (HTN) are highly prevalent comorbid risk factors for heart failure with preserved ejection fraction (HFpEF). Obesity and HTN independently increase sympathetic nervous activity and impair muscle blood flow during exercise. Previous work has reported attenuated limb blood flow in patients with HFpEF; however, these findings were compared to controls with dissimilar comorbidities and during small muscle mass exercise. It is unclear if HFpEF alters muscle blood flow responses independent of the obesity- and HTN-mediated alterations. Hypothesis: We hypothesized the muscle blood flow response during cycling would be lower in HFpEF patients than age, sex, BMI, and HTN matched controls (CTL). Methods: HFpEF patients (n=14, 9M/5W, 71±7yrs, 32±4 kg/m 2 ) and CTL (n=12, 8M/4W, 69±7yrs, 31±4 kg/m 2 ) performed an incremental cycling test. Blood pressure was measured by manual sphygmomanometry, cardiac output (Q) by open-circuit acetylene wash-in technique, and systemic vascular resistance (SVR) was calculated. Vastus lateralis blood flow index (BFI) was measured by near-infrared spectroscopy and indocyanine green dye injections and venous norepinephrine concentration was measured. Changes from rest to 40 W of the incremental test are reported. Results: Resting Q, mean arterial pressure, SVR, and venous norepinephrine concentration were not statistically different between groups (p>0.18). From rest to 40 W, the increases in Q (CTL: 3.9±0.8 vs. HFpEF: 3.6±0.7 L/min), mean arterial pressure (CTL: 5.7±2.7 vs. HFpEF: 6.6±6.1 mmHg), and SVR (CTL: -7.3±2.1 vs. HFpEF: -6.0±2.0 mmHg/L/min) were not statistically different between groups (all, p>0.13). The HFpEF group had smaller increases in vastus lateralis BFI at 40 W compared to CTL (CTL: 7.2±3.6 vs. HFpEF: 4.2±2.6 fold-increase from rest) (p=0.02). The HFpEF group had greater increases in venous norepinephrine concentration from rest to 40 W than CTL (CTL: 164±216 vs. HFpEF: 377±247 pg/mL) (p=0.05). Conclusions: Our findings suggest that, compared to age, sex, BMI, and HTN matched controls, patients with HFpEF have an impaired locomotor muscle blood flow response during submaximal cycling exercise likely due to higher locomotor muscle vascular resistance.