Open Access
Feature Article

The cardiac complications of obesity

Elizabeth Paratz, Sonny Palmer, Justin Mariani


Dr Paratz is a Cardiologist at St Vincent’s Hospital and the Baker Heart & Diabetes Institute, Melbourne. Associate Professor Palmer is an Interventional and Structural Cardiologist at St Vincent’s Hospital, Melbourne. Associate Professor Mariani is an Interventional Heart Failure Specialist at The Alfred Hospital, Melbourne, Vic.


Obesity is a powerful risk factor for cardiovascular events, but accumulating data suggest that patients can remodel their hearts and improve health outcomes by losing weight.

Key Points

  • The majority of people in Australia have overweight or obesity.
  • The impact of obesity on cardiovascular (CV) risk is multifactorial and self-amplifying.
  • Patients with morbid obesity and coronary syndromes are prone to increased procedural complications and poorer outcomes than patients of normal weight.
  • Doctors are strongly advised to inform their patients who have obesity of their elevated CV risk profile and mortality.
  • Data increasingly suggest that patients can remodel their hearts and health outcomes by losing weight.
  • Accumulating evidence from prospective trials has shown that various forms of bariatric surgery may have positive impacts on CV endpoints.

A 27-year-old woman attends your practice regularly. She has morbid obesity, with a body mass index (BMI) of 47 kg/m2. Her comorbidities include hypertension, for which you have commenced her on perindopril 5 mg daily, and newly diagnosed atrial fibrillation (AF), for which you have prescribed metoprolol 25 mg twice daily. You are considering referring her to a cardiologist for possible atrial fibrillation ablation (pulmonary vein isolation). 

What is the significance of this patient’s morbid obesity in terms of elevating her cardiovascular (CV) risk? What is the connection between her morbid obesity and her other comorbidities? If she were able to lose weight now, would she be able to reverse her CV risk profile and alleviate her current comorbidities? What options are available for weight loss?


Obesity in Australia 

Australia, like all other developed countries, is experiencing a ballooning epidemic of obesity. The majority of people in Australia now have overweight or obesity (Table 1), with a fourfold increase in obesity having occurred over the past 30 years.1 The largest increase has occurred in the group of individuals with ‘morbid obesity’, equating to a BMI of 40 kg/m2 or above. Consequently many obesity researchers have begun to use additional classifications such as ‘super obesity’ (BMI ≥50 kg/m2) and ‘super-super obesity’ (BMI ≥60 kg/m2).2


The rise in morbid obesity impacts heavily on the Australian economy, with annual costs calculated at $58 billion.3 This figure includes direct healthcare costs for morbid obesity and its known complications, disability pension costs and loss of productivity. In the Global Burden of Disease Study, obesity was identified as the strongest contributor to the burden of disease for modern Australasia.4


In many ways, the epidemic of obesity in the 21st century evokes the epidemic of smoking in the 20th century. Both are culturally-dependent epidemics, and both obesity and smoking are powerful modifiable risk factors for CV events. Despite the common misperception, morbid obesity is in fact a significantly stronger risk factor for premature myocardial infarction than smoking.5 Highly successful public health campaigns significantly reduced the prevalence of cigarette smoking; health organisations and doctors will need to campaign against environmental factors enabling obesity in a similar manner to promote national CV health. Food companies may resist (like cigarette companies), with advertising of unhealthy foods, promotion of such foods to children, and sponsoring of events.