Obstructive sleep apnea and electrocardiographic P-wave morphology.

INTRODUCTION: Obstructive sleep apnea (OSA) is a highly prevalent sleep disorder with important cardiovascular implications. Left atrial abnormality can be identified by electrocardiographic P-wave morphology and is considered an important risk for atrial fibrillation (AF) and stroke, both of which have been associated with OSA. We hypothesized that severity of OSA would be associated with more abnormal electrocardiographic P-wave morphology as indicated by P-wave terminal force in V1 (PTFV1 ) and P-wave area in V1 (PWAV1 ). METHODS: Patients who underwent clinically indicated polysomnography and had 12-lead ECG were identified through medical record review. Logistic regression was used to determine the associations between the measures of OSA severity (apnea hypopnea index [AHI] and mean nocturnal oxygen [O2 ] saturation) and abnormal PTFV1 and PWAV1 (defined by >75% percentile value of the studied cohort) adjusting for age, sex, body mass index, and hypertension. RESULTS: A total of 261 patients (mean age: 57 years old, male: 52%) were included in the study. Multivariate analysis showed that AHI was associated with abnormal PTFV1 (>7,280 µV ms) and PWAV1 (>1,000 µV ms; OR: 1.5; 95% CI [1.1, 2.0], p = 0.008; OR: 1.5 [1.1, 2.1], p = 0.005 per 1 SD increase in AHI, respectively). Mean O2 saturation was associated with abnormal PWAV1 (OR: 0.72 [0.54, 0.98], p = 0.03). Results remained unchanged after excluding patients taking AV nodal blocking agents. CONCLUSION: In a sleep clinic cohort, there was significant association between OSA severity and ECG-defined left atrial abnormality.

Health solutions to improve post-intensive care outcomes: a realist review protocol.

BACKGROUND: While 80% of critically ill patients treated in an intensive care unit (ICU) will survive, survivors often suffer a constellation of new or worsening physical, cognitive, and psychiatric complications, termed post-intensive care syndrome. Emerging evidence paints a challenging picture of complex, long-term complications that are often untreated and culminate in substantial dependence on acute care services. Clinicians and decision-makers in the Fraser Health Authority of British Columbia are working to develop evidence-based community healthcare solutions that will be successful in the context of existing healthcare services. The objective of the proposed review is to provide the theoretical scaffolding to transform the care of survivors of critical illness by a synthesis of relevant clinical and healthcare service programs. METHODS: Realist review will be used to develop and refine a theoretical understanding of why, how, for whom, and in what circumstances post-ICU program impact ICU survivors' outcomes. This review will follow the recommended five steps of realist review which include (1) clarifying the scope of the review and articulating a preliminary program theory, (2) searching for evidence, (3) appraising primary studies and extracting data, (4) synthesizing evidence and sharing conclusions, and (5) disseminating and implementing recommendations. DISCUSSION: This realist review will provide a program theory, encompassing the contexts, mechanisms, and outcomes, to explain how clinical and health service interventions to improve ICU survivor outcomes operate in different contexts for different survivors, and with what effect. This review will be an evidentiary pillar for health service development and implementation by our knowledge user team members as well as advance scholarly knowledge relevant nationally and internationally. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42018087795.

Haemodynamically Derived Pulmonary Artery Pulsatility Index Predicts Mortality in Pulmonary Arterial Hypertension.

BACKGROUND: Pulmonary artery (PA) pulsitility index (PAPi) is a novel haemodynamic index shown to predict right ventricular failure in acute inferior myocardial infarction and post left ventricular assist device surgery. We hypothesised that PAPi calculated as [PA systolic pressure - PA diastolic pressure]/right atrial pressure (RAP) would be associated with mortality in the National Institutes of Health Registry for Primary Pulmonary Hypertension (NIH-RPPH). METHODS: The impact of PAPi, the Pulmonary Hypertension Connection (PHC) risk score, right ventricular stroke work, pulmonary artery capacitance (PAC), other haemodynamic indices, and demographic characteristics was evaluated in 272 NIH-RPPH patients using multivariable Cox proportional hazards (CPH) regression and receiver operating characteristic (ROC) analysis. RESULTS: In the 272 patients (median age 37.7+/-15.9years, 63% female), the median PAPi was 5.8 (IQR 3.7-9.2). During 5years of follow-up, 51.8% of the patients died. Survival was markedly lower (32.8% during the first 3years) in PAPi quartile 1 compared with the remaining patients (58.5% over 3years in quartiles 2-4; p<0.0001). The best multivariable CPH survival model included PAPi, the PHC-Risk score, PAC, and body mass index (BMI). In this model, the adjusted hazard ratio for death with increasing PAPi was 0.946 (95% CI 0.905-0.989). The independent ROC areas for 5-year survival based on bivariable logistic regression for PAPi, BMI, PHC Risk, and PAC were 0.63, 0.62, 0.64, and 0.65, respectively (p<0.01). The ROC area for 5-year survival for the multivariable logistic model with all four covariates was 0.77 (p<0.0001). CONCLUSIONS: Pulmonary artery pulsatility index was independently associated with survival in PAH, highlighting the utility of PAPi in combination with other key measures for risk stratification in this population.

Increased Pulmonary-Systemic Pulse Pressure Ratio Is Associated With Increased Mortality in Group 1 Pulmonary Hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is characterised by remodelling of the pulmonary vasculature leading to right ventricular (RV) failure. The failing RV, through interventricular uncoupling, deleteriously impacts the left ventricle and overall cardiac efficiency. We hypothesised that the ratio of the pulmonary artery pulse pressure to the systemic pulse pressure ("pulmonary-systemic pulse pressure ratio", or PS-PPR) would be associated with mortality in PAH. METHODS: We conducted a retrospective analysis of 262 patients in the National Institute of Health Primary Pulmonary Hypertension Registry (NIH-PPH). We evaluated the association between the PS-PPR and mortality after adjustment for the Pulmonary Hypertension Connection (PHC) risk equation. RESULTS: Among 262 patients (mean age 37.5±15.8years, 62.2% female), median PS-PPR was 1.04 (IQR 0.79-1.30). In the Cox proportional hazards regression model, each one unit increase in the PS-PPR was associated with more than a two-fold increase in mortality during follow-up (HR 2.06, 95% CI 1.40-3.02, p=0.0002), and this association of PS-PPR with mortality remained significant in the multivariable Cox model adjusted for the PHC risk equation, mean pulmonary artery pressure, and body mass index (BMI) (adjusted HR 1.81, 95% CI 1.13-2.88, p=0.01). Furthermore, PS-PPR in the upper quartile (>1.30) versus quartiles 1-3 was associated with a 68% increase in mortality after adjustment for these same covariates (adjusted HR 1.68, 95% CI 1.13-2.50, p=0.01). CONCLUSIONS: Pulmonary-systemic pulse pressure ratio, a marker of biventricular efficiency, is associated with survival in PAH even after adjustment for the PHC risk equation. Further studies are needed on the wider applications of PS-PPR in PAH patients.

Right atrial to left atrial volume index ratio is associated with increased mortality in patients with pulmonary hypertension.

BACKGROUND: Pulmonary hypertension (PH) is characterized by increased pulmonary vascular resistance leading to right heart failure. Elevated right atrial (RA) pressure reflects right ventricular (RV) pressure overload and is an established risk factor for mortality in PH. We hypothesized that PH patients with an increased ratio of RA to LA volume index (RAVI/LAVI), would have increased mortality. METHODS: We evaluated the association of RAVI/LAVI with mortality in 124 patients seen at a single academic center's PH clinic after adjusting for the REVEAL risk score, an established risk score in PH. LA and RA volume indices were measured in the four-and two-chamber views by two independent researchers. Multivariable logistic regression was used to model the independent association of RAVI/LAVI with survival. RESULTS: Among 124 patients (mean age 62 ± 12.7 years, 68.6% female), each unit increase in RAVI/LAVI was associated with a nearly twofold increase in mortality (OR: 1.91, 95% CI: 1.20-3.04). In a multivariable logistic regression, each unit increase in RAVI/LAVI was associated with a nearly twofold increase in mortality (OR: 1.73, 95% CI: 1.003-2.998). Furthermore, RAVI/LAVI in the highest quartile (>1.42) was significantly associated with elevated right atrial pressure (RAP) to pulmonary artery wedge pressure ratio (RAP/PAWP) (0.76 ± 0.41, P = 0.02) compared with the lowest quartile (<0.77), suggesting an interaction between invasive hemodynamic data, atrial structural changes, and mortality in PH. CONCLUSIONS: Increased RAVI/LAVI in PH is associated with decreased survival and accounts for atrial structural remodeling related to invasive hemodynamics. These findings support further study of this index in predicting outcomes in PH.

Decreased pulmonary arterial proportional pulse pressure is associated with increased mortality in group 1 pulmonary hypertension.

BACKGROUND: This study evaluated the utility of a novel index, pulmonary arterial (PA) proportional pulse pressure (PAPP; range 0-1, defined as [PA systolic pressure - PA diastolic pressure] / PA systolic pressure), in predicting mortality in patients with World Health Organization group 1 pulmonary hypertension (PH). HYPOTHESIS: Low PAPP is associated with increased 5-year mortality independent of a validated contemporary risk-prediction equation (Pulmonary Hypertension Connection [PHC] equation). METHODS: In a group of 262 patients in the National Institutes of Health Primary Pulmonary Hypertension (NIH-PPH) Registry, PAPP and the PHC risk equation were used to predict mortality during 5 years of follow-up using Cox proportional hazards models. Kaplan-Meier survival curves were used to compare mortality among PAPP quartiles, and significance was tested using the log-rank test. RESULTS: Patients in the lowest quartile (PAPP ≤0.47) had a significantly higher 5-year mortality than did patients in higher quartiles (log-rank P = 0.016). In a Cox model adjusted for the PHC equation, PAPP remained significantly associated with 5-year mortality (hazard ratio: 0.74 per 0.10 increase in PAPP, 95% confidence interval: 0.61-0.90). The χ2 statistic for the single PAPP covariate in this model was 8.8 (P = 0.003), which compared favorably with the χ2 statistic of 15.2 (P < 0.0001) for the multivariable PHC equation. CONCLUSIONS: PAPP, an index of ventricular-arterial coupling, is independently associated with survival in World Health Organization group 1 PH. The use of this easily measurable index for guiding risk stratification needs further investigation.