Having A Low BMI Increases Mortality Risk After Having A Heart Attack

The association between being underweight and death after an acute myocardial infarction (AMI) has been known previously, but it wasn't clear whether the risk was connected to just having a low body mass index (BMI), or whether medical conditions causing the patient to be underweight was the actual problem. 

Researchers at Yale University conducted a study on elderly patients who were hospitalized for an AMI. This study was done to compare the short- and long-term mortality risk in both underweight and normal weight patients. This was done while also considering other important factors such as the presence of other comorbid conditions and frailty of the patient.

The questions that this study sought out to answer were the following:

1. Does comprehensive risk adjustment for comorbidities and frailty measures explain the increased mortality in underweight patients, after an AMI, as compared to normal weight patients?
2. In patients with AMI who do not have any chronic illness and who are assumed to not be cachexic, is the relationship between being underweight and mortality also observed?

The research

Over 55,000 patients' data was analyzed over a 17 year period. Comparisons of the mortality rate amongst these patients were done at 30 days, 1 year, 5 years and 17 years after the initial AMI. 

The data showed that the survival curves for the underweight patients and normal weight patients had separated early and then remained that way over the 17 year period. This suggested that the underweight patients had remained at am increased survival disadvantage over that time. Similar findings were found among the group of underweight patients who had no comorbidities, as they had a 30 day adjusted mortality similar to that of normal weight patients, but with an increased mortality risk over the long term.

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The importance of this study

The researchers weren't able to accurately measure cachexia and were also not able to determine the initial cause of the low BMI in the involved patients.

Conclusive message of the study

The researchers of this study noted that their findings warranted additional research to be done in underweight patients, as they were frequently excluded from studies that evaluated the BMI in patients with coronary artery disease (CAD). 

From a clinical point of view, it was also suggested that strategies to promote weight gain in underweight patients who had suffered an AMI would be worthy of further testing.

Low Body Mass Index: Causes, Complications And Treatment 

Definition

Causes 

Being underweight can be a primary causative issue, but it may also be secondary to or as a symptom of an underlying disease.

Genetics may play a role in causing a person to be underweight, but there are other important causes which may include the following issues:

• Hyperthyroidism.
• Cancer.
• Tuberculosis.
• Drug use.
• Gastrointestinal or liver pathology.
• Eating disorders such as anorexia.

Complications

The following are issues which may be experienced by underweight individuals.

• Poor physical stamina.
• Weakened immune system resulting in persistent infections.
• Amenorrhoea (absence of mentruation).
• Infertility.
• Anaemia.
• Hair loss.
• Increased risk for osteoporosis and therefore pathological fractures.
• Deficiencies in essential vitamins, minerals and amino acids.
• Increased risk of mortality following cardiovascular events, as mentioned.

 Treatment

The following are suggestions regarding changes in dietary habits which can be incorporated. These may help in gaining weight in a healthy manner.

• Eat more frequently - underweight patients tend to get fuller quicker. Therefore, eating 5-6 smaller meals every day rather than 2-3 larger ones can increase one's caloric intake.
• Consume nutrient-rich foods -  pastas, whole-grain breads, cereals, nuts and seeds, dairy products, and lean protein products are excellent choices.
• Make a note at what times fluids are consumed - drinking fluids before eating meals tends to decrease one's appetite. Better choices would be to either consume small amounts of high calorie drinks before meals, or to drink fluids 30 minutes after eating a meal.

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• Drink shakes and/or smoothies - Healthy shakes and/or smoothies made from milk and fruits or fruit juices are better choices over drinks, such as coffee and diet beverages, which have low calories and are low in nutritional value.
• Snack in between meals - dried fruits, cheeses and nuts are excellent in-between snack choices. A bedtime snack such as an avocado, cheese and lean meat sandwich is high in calories and nutrients.
• Refined foods - high sugary content foods can still increase the risk of diabetes, even in underweight patients as the process occurs due to cells becoming resistant to the effects of insulin. An occasional treat is still adequate though.
• Adding extra calories to meals - the addition of cheese to mashed potatoes, broccoli bakes and scrambled eggs are a good way to increase calories in meals.
• Exercising - weight lifting exercises are a good way to increase muscle mass and bone density. Although there will be an initial decline in mass, the long-term result will be beneficial. Exercising can also help to stimulate the appetite.
• Appetite stimulants - Natural stimulants would include suggesting vitamin B complex supplements which help to improve one's appetite. Prescription drugs are usually reserved for patients who are cachexic due to chronic illnesses. These patients would discuss their available options with their doctor who would prescribe the appropriate medication to them.