Association of the Obesity Paradox With Objective Physical Activity in Patients at High Risk of Sudden Cardiac Death

Obesity paradox in patients with reduced ejection fraction eligible for device implantation - an observational study

AIMS

Patients with obesity have an overall higher cardiovascular risk, at the same time obesity could be associated with a better outcome in a certain subgroup of patients, a phenomenon known as the obesity paradox. Data are scarce in candidates for cardiac resynchronization therapy (CRT). We aimed to investigate the association between body mass index (BMI) and all-cause mortality in patients eligible for CRT.

METHODS

Altogether 1,585 patients underwent cardiac resynchronization therapy between 2000-2020 and were categorized based on their BMI, 459 (29%) patients with normal weight (BMI < 25 kg/m2), 641 (40%) patients with overweight (BMI 25- < 30 kg/m2) and 485 (31%) with obesity (BMI ≥ 30 kg/m2). The primary endpoint was all-cause mortality, heart transplantation, and left ventricular assist device implantation. We assessed periprocedural complications and 6-month echocardiographic response.

RESULTS

Normal-weight patients were older compared to patients with overweight or obesity (70 years vs. 69 years vs. 68 years; P ‹0.001), respectively. Sex distribution, ischaemic aetiology, and CRT-D implantation rates were similar in the three patient groups. Diabetes mellitus (BMI < 25 kg/m2 26% vs. BMI 25- < 30 kg/m2 37% vs. BMI ≥ 30 kg/m2 48%; P ‹0.001) and hypertension (BMI < 25 kg/m2 71% vs. BMI 25- < 30 kg/m2 74% vs. BMI ≥ 30 kg/m2 82%; P ‹0.001) were more frequent in patients with overweight and obesity. During the mean follow-up time of 5.1 years, 973 (61%) reached the primary endpoint, 66% in the BMI < 25 kg/m2 group, 61% in the BMI 25- < 30 kg/m2 group and 58% in the BMI ≥ 30 kg/m2 group (log-rank P‹0.05). Patients with obesity showed mortality benefit over normal-weight patients (HR 0.78; 95%CI 0.66-0.92; P = 0.003). The obesity paradox was present in patients free from diabetes, atrial fibrillation, and ischemic events. Periprocedural complication rates did not differ in the three groups (BMI < 25 kg/m2 25% vs. BMI 25- < 30 kg/m2 28% vs. BMI ≥ 30 kg/m2 26%; P = 0.48). Left ventricular ejection fraction improved significantly in all patient groups (BMI < 25 kg/m2 median∆ $$ \Delta $$ -LVEF 7% vs. BMI 25- < 30 kg/m2 median∆ $$ \Delta $$ -LVEF 7.5% vs. BMI ≥ 30 kg/m2 median∆ $$ \Delta $$ -LVEF 6%; P < 0.0001) with a similar proportion of developing reverse remodeling (BMI < 25 kg/m2 58% vs. BMI 25- < 30 kg/m2 61% vs. BMI ≥ 30 kg/m2 57%; P = 0.48); P = 0.75).

CONCLUSIONS

The obesity paradox was present in our HF cohort at long-term, patients underwent CRT implantation with obesity and free of comorbidities showed mortality benefit compared to normal weight patients. Patients with obesity showed similar echocardiographic response and safety outcomes compared to normal weight patients.

Associations between body mass index and all-cause mortality: A systematic review and meta-analysis

Fasting insulin and c-reactive protein confound the association between mortality and body mass index. An increase in fat mass may mediate the associations between hyperinsulinemia, hyperinflammation, and mortality. The objective of this study was to describe the "average" associations between body mass index and the risk of mortality and to explore how adjusting for fasting insulin and markers of inflammation might modify the association of BMI with mortality. MEDLINE and EMBASE were searched for studies published in 2020. Studies with adult participants where BMI and vital status was assessed were included. BMI was required to be categorized into groups or parametrized as non-first order polynomials or splines. All-cause mortality was regressed against mean BMI squared within seven broad clinical populations. Study was modeled as a random intercept. β coefficients and 95% confidence intervals are reported along with estimates of mortality risk by BMIs of 20, 30, and 40 kg/m2 . Bubble plots with regression lines are drawn, showing the associations between mortality and BMI. Splines results were summarized. There were 154 included studies with 6,685,979 participants. Only five (3.2%) studies adjusted for a marker of inflammation, and no studies adjusted for fasting insulin. There were significant associations between higher BMIs and lower mortality risk in cardiovascular (unadjusted β -0.829 [95% CI -1.313, -0.345] and adjusted β -0.746 [95% CI -1.471, -0.021]), Covid-19 (unadjusted β -0.333 [95% CI -0.650, -0.015]), critically ill (adjusted β -0.550 [95% CI -1.091, -0.010]), and surgical (unadjusted β -0.415 [95% CI -0.824, -0.006]) populations. The associations for general, cancer, and non-communicable disease populations were not significant. Heterogeneity was very large (I2  ≥ 97%). The role of obesity as a driver of excess mortality should be critically re-examined, in parallel with increased efforts to determine the harms of hyperinsulinemia and chronic inflammation.

The fatter, the better in old age: the current understanding of a difficult relationship

PURPOSE OF REVIEW

Obesity has shown a protective effect on mortality in older adults, also known as the obesity paradox, but there are still controversies about this relationship.

RECENT FINDINGS

Recent studies have shown a J or U-shaped relationship between BMI and mortality, wherein an optimal range is described between 22 and 37 kg/m2 depending on the condition. Many mechanisms can explain this protective effect of higher BMI, fat/muscle mass storage, more aggressive treatment in obese individuals, loss of bone mineral content and selection bias. However, BMI must be used with caution due to its limitations to determine body composition and fat distribution.

SUMMARY

Although BMI is an easy tool to evaluate obesity, its protective effect may be present to certain extend, from normal range to class I obesity (BMI 30-34.9 kg/m2), but then it becomes detrimental. Skeletal muscle mass and muscle function associated with adipose tissue assessment can add valuable information in the risk stratification. Further studies should be performed prospectively, adjust BMI for cofounding variable and consider other elderly subpopulations. To promote healthy ageing, excessive fat mass should be avoided and maintenance or improvement of skeletal muscle mass and muscle function should be stimulated in older adults.

Development and validation of a novel index for the differential diagnosis of corticotropin-dependent Cushing syndrome

PURPOSE

To develop an index for the differential diagnosis of corticotropin-dependent Cushing syndrome (CS).

METHODS

The development cohort included 112 consecutive patients with clinicopathologically confirmed corticotropin-dependent CS at the Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, from December 2004 to May 2020, and data of 126 patients from studies published from 2016 to August 2020, identified through search in PubMed, Embase and the Cochrane Library, was extracted for external validation. The index was calculated as the product of plasma adrenocorticotropic hormone (ACTH, pmol/L) and urinary free cortisol (UFC, nmol/24 h) divided by 10,000. The discriminative ability was tested using receiver operating characteristics (ROC) curve analysis.

RESULTS

In development cohort, area under curve of ROC analysis of the ACTH-UFC index in identifying Cushing disease (CD) was 0.977. The diagnostic accuracy of ACTH-UFC index ≤ 11 was comparable to that of 48 h 8 mg/d high-dose dexamethasone test (HDDST) in identifying CD, with sensitivity, specificity, positive and negative likelihood ratios of 96.6%, 87.5%, 7.73, and 0.04, respectively. The sensitivity of ACTH-UFC index ≤ 11 in parallel combination with pituitary magnetic resonance imaging (MRI) was 100% for identifying CD. The performance of the ACTH-UFC index in parallel or serial combination with pituitary MRI was similar in the validation cohort.

CONCLUSIONS

ACTH-UFC index provides a rapid, convenient and non-invasive adjunctive approach for the differential diagnosis of corticotropin-dependent CS, with no risk of aggravating metabolic disturbances. Investigations for ectopic causes of corticotropin-dependent CS should be performed with ACTH-UFC index > 11 and negative contrasted pituitary MRI.