Elevated sympathetic-mediated vasoconstriction at rest but intact functional sympatholysis during exercise in heart failure with reduced ejection fraction

BACKGROUND

Patients with heart failure with reduced ejection fraction (HFrEF) have exaggerated sympathoexcitation and impaired peripheral vascular conductance. Evidence demonstrating consequent impaired functional sympatholysis is limited in HFrEF. This study aimed to determine the magnitude of reduced limb vascular conductance during sympathoexcitation and whether functional sympatholysis would abolish such reductions in HFrEF.

METHODS

Twenty patients with HFrEF and 22 age-matched controls performed the cold pressor test (left foot 2-min in -0.5[1] °C water) alone (CPT) and with right handgrip exercise (EX+CPT). Right forearm vascular conductance (FVC), forearm blood flow (FBF), and mean arterial pressure (MAP) were measured.

RESULTS

Patients with HFrEF had greater decreases in %ΔFVC and %ΔFBF during CPT (both P<0.0001) but not EX+CPT (P=0.449, P=0.199) compared to controls, respectively. %ΔFVC and %ΔFBF decreased from CPT to EX+CPT in patients with HFrEF (both P<0.0001) and controls (P=0.018, P=0.015), respectively. MAP increased during CPT and EX+CPT in both groups (all P<0.0001). MAP was greater in controls compared to patients with HFrEF during EX+CPT (P=0.025) but not CPT (P=0.209).

CONCLUSIONS

Acute sympathoexcitation caused exaggerated peripheral vasoconstriction and reduced peripheral blood flow in patients with HFrEF. Handgrip exercise abolished sympathoexcitatory-mediated peripheral vasoconstriction and normalized peripheral blood flow in patients with HFrEF. These novel data reveal intact functional sympatholysis in the upper limb and suggest exercise-mediated, local control of blood flow is preserved when cardiac limitations that are cardinal to HFrEF are evaded with dynamic handgrip exercise.

Muscle metaboreflex control of left ventricular systolic function in heart failure with reduced ejection fraction

INTRODUCTION

Heart failure with reduced ejection fraction (HFrEF) exhibits exaggerated sympathoexcitation and altered cardiac and vascular responses to muscle metaboreflex activation (MMA). However, left ventricular (LV) responses to MMA are not well studied in patients with HFrEF. The purpose of this study was to examine LV function during MMA using cardiac magnetic resonance imaging (MRI) in patients with HFrEF.

METHODS

Thirteen patients with HFrEF and 18 healthy age-matched controls underwent cardiac MRI during rest and MMA. MMA protocol included 6-min of isometric handgrip exercise followed by 6-min of brachial post-exercise circulatory occlusion. LV stroke volume index (SVi), end-systolic volume index (ESVi), end-diastolic volume index (EDVi) and global longitudinal strain (GLS) were measured by 2- and 4-chamber cine images. Volumes were indexed to body surface area. Heart rate (via ECG) and brachial mean arterial pressure (MAP) were recorded. Cardiac output and total peripheral resistance (TPR) were calculated.

RESULTS

SVi decreased during MMA in HFrEF (P=0.037) but not controls (P=0.392). ESVi (P=0.007) and heart rate (P<0.001) increased during MMA in HFrEF but not controls (P≥0.170). TPR (P=0.021) and MAP (P<0.001) increased during MMA in both groups. Cardiac output (P=0.946), EDVi (P=0.177), and GLS (P=0.619) were maintained from rest to MMA in both groups.

CONCLUSIONS

Despite similarly maintained cardiac output, LV strain, and increased TPR in HFrEF and control groups, SVi decreased, and heart rate increased during MMA in patients with HFrEF. These findings suggest an impaired contractility reserve in response to increased TPR during MMA in HFrEF.

Loeys-Dietz syndrome and isolated severe ostial left main coronary stenosis presenting as ventricular fibrillation arrest and biventricular takotsubo syndrome in a 25-year-old patient

We present the case of a previously healthy 25-year-old woman who presented with an out-of-hospital ventricular fibrillation arrest. Postresuscitation ECG did not show any evidence of ST segment elevation. Echocardiogram showed regional wall abnormalities in keeping with takotsubo syndrome (TTS). Urgent coronary angiogram to rule out malignant congenital coronary artery anomaly revealed an isolated severe ostial left main coronary artery (LMCA) stenosis, a rare disease, approximately 0.2% in previous case series. The LMCA was aneurysmal. Genetic studies revealed a novel frameshift pathogenic variant in the transforming growth factor B two ligand gene (TGFB2) gene, suggestive of Loeys-Dietz syndrome (LDS) type 4, an aggressive vascular disease. Ostial LMCA stenosis has not been previously reported in LDS, and we outline the management of this unique disease combination. We also reflect on its presentation as TTS and infer that TTS and acute coronary syndromes are not mutually exclusive.

Trends in Patient Characteristic, Cost, and Mortality Among Mechanically Ventilated Adult Patients With Congenital Heart Disease in the United States

Background

There is an increasing number of adults with congenital heart disease (ACHD), but critically ill patients with ACHD remain understudied. The objective of this study was to evaluate patient characteristics and trends in mortality of mechanically ventilated patients with ACHD.

Methods

We evaluated ACHD with an ICD-9 procedure code for mechanical ventilation using the National Inpatient Sample (NIS), a public all-payer inpatient United States database, from 2005 to 2014. Primary and secondary outcomes were evaluated using multivariable logistic regression.

Results

There were 10,962 of 77,334,704 discharges, representing 52,876 (0.6%) hospitalizations that were for patients with ACHD who required mechanical ventilation (MV). Mean age was 59 years (interquartile range: 45-71); 45.3% were female patients. The number of patients with ACHD requiring MV increased over the years (2342 to 7775, P < 0.001). Age and comorbidities of this cohort also increased (55 to 59, P < 0.001; 1 to 2, P < 0.001). Case-fatality ratio remained stable over the years (0.254 to 0.259, P = 0.42). Median cost of hospital stay was USD $49,583 and remained stable over the study period (P = 0.42), whereas total cost increased from $115 million to $564 million (P < 0.001).

Conclusions

The number of mechanically ventilated ACHD has increased over the years. Remarkably, despite an increase in the age and comorbidity burden in this cohort, case-fatality ratio of these patients and the cost per patient remained stable. Nonetheless, there is a growing need for health care resources in the management of this cohort of patients. Further studies will need to be conducted to evaluate the underlying physiological impact and prognosis of MV in specific subsets of ACHD.

Reducing Unnecessary Noninvasive Testing for Inpatients With Unstable Angina: The RUNIT Protocol

Background

Routine inpatient transthoracic echocardiography (TTE) for patients with unstable angina is common, but it anecdotally adds little value to clinical care. A practice audit at our academic hospital demonstrated that 61.5% of patients with troponin-negative chest pain (TNCP) had normal left ventriculography (LVG) during coronary angiography and normal TTE on the same admission (duplicate testing).

Methods

We developed the Reducing Non-Invasive Testing (RUNIT) protocol, a clinical algorithm applied by clinical nurses to patient with TNCP. We performed a prospective assessment of rate of duplicate testing before and after intervention. If patients met certain simple clinical criteria, their TTE was cancelled (RUNIT positive). Patients then proceeded to have either coronary angiography with LVG or noninvasive risk stratification. We aimed to reduce duplicate testing by 25% over a 1-year period. Balancing measures included pathology on ordered TTEs, 30-day readmission, length of stay, and number of LVG.

Results

Among 254 patients admitted with TNCP over 12 months, we reduced duplicate testing from 61.5% (before intervention) to 34% (P = 0.001). There was no clinical difference in 30-day readmission (0.9% vs 0.7%), and length of stay was significantly shorter in RUNIT positive (3.48 vs 4.16 days, P = 0.02). The majority of duplicate TTEs did not reveal any management-informing pathology. RUNIT-positive patients underwent more LVG than RUNIT-negative patients (78.3% vs 62.8%, P = 0.008).

Conclusion

We achieved a sustained reduction in reflexive TTE ordering in patients with TNCP, and we discuss the potential of nursing-led interventions to address other areas of low value care in cardiology.

Frequency and Consequences of Influenza Vaccination in Adults With Congenital Heart Disease

Immunization against influenza is a critical, but perhaps underappreciated prevention of morbidity and mortality in the cardiac population. The purpose of the present study is to examine influenza vaccination rates in adults with congenital heart disease (ACHD). A secondary purpose is to explore whether there is an association between demographic, medical, and behavioral variables and receipt of the influenza vaccination. Of the 183 consecutive ACHD patients who were contacted, 123 responded to our telephone survey. Mean age was 38.4 ± 14.7, with the most common type of lesion complexity being moderate (65.3%), followed by simple (21.0%) and severe (13.7%). Overall, 53 respondents reported undergoing influenza vaccination in the previous season. Fifty-two percent of all subjects claimed they were notified of the benefits of vaccination by their physician. Univariate analysis revealed that older age (p = 0.006), female gender (p = 0.027), perceived susceptibility to influenza illness (p <0.001), perceived severity of the influenza illness (p <0.001), perceived benefits of the influenza vaccination (p <0.001), side effects from previous immunization (p = 0.006), and physician recommendation (p = 0.008) were predictors of receipt of influenza vaccination. On multivariate analyses, however, only side effects from previous immunization was a predictor (odds ratio = 0.34 [95% confidence interval 0.13 to 0.91]), whereas physician recommendation was numerically, but not statistically, significant (odds ratio 2.01 [95% confidence interval 0.85 to 4.78]). Our study demonstrated that less than 50% of ACHD population receives influenza vaccination. We believe educating both the patients about the side effects of vaccination and the physicians about their role in counseling ACHD patients will increase the vaccination rates in this high-risk population.

Myocardial Perfusion Scans and Mortality in Asymptomatic Patients Awaiting Renal Transplantation

Cardiac risk assessment for asymptomatic patients awaiting renal transplantation is controversial. Patients awaiting renal transplantation in Southern Saskatchewan from 2005 to 2015 were retrospectively reviewed. Patients underwent cardiac risk stratification with stress myocardial perfusion scan. Baseline clinical characteristics, nuclear scan results, all-cause mortality, and cardiovascular events were analyzed. Abnormal scans were defined as studies with reversible defects, wall motion abnormalities, lung uptake, or transient ischemic dilation. Descriptive statistics and survival analysis were calculated. Charts from 285 consecutive patients with 608 nuclear scans were analyzed. Mean age was 55.2 ± 11.7 years and 34.7% were female. Forty-three (15.1%) patients were transplanted and 99 (40.9%) patients died while awaiting renal transplantation. One hundred fifty-three patients (63.2%) had at least one abnormal scan. The mean follow-up period was 5.47 ± 3.11 years. An abnormal scan was not associated with decreased survival and/or coronary events (hazard ratio: 0.94, P = .77; 95% confidence intervals: 0.62 to 1.43). Patients awaiting renal transplantation in Saskatchewan with abnormal myocardial perfusion scans were not at greater risk of death or coronary events.