Anationwide study in France reports heart failure patients lost weight during the 2019 heatwave, which is a sign that their condition is getting worse. This weight loss is closely related to the hot temperatures. ESC Heart Failure, a journal of the European Society of Cardiology, published the study yesterday (ESC).
“This study is the first to show a strict relationship between ambient temperature and body weight in heart failure patients,” said study author Professor François Roubille of Montpellier University Hospital, France. “The finding is timely given the heatwaves again this year. The weight loss we observed in people with heart failure may lead to low blood pressure, especially when standing up, and renal failure, and is potentially life-threatening. With rising temperatures forecast for the future, clinicians and patients should be ready to reduce the dose of diuretics when weight loss occurs.”
The heart does not pump blood around the body as effectively in people with heart failure. Waste products build up, resulting in breathlessness and fluid retention in the lungs, legs, and abdomen. Since weight gain is linked to congestion, the primary reason for hospital admission, weight is the cornerstone of monitoring. Diuretics, also known as water pills, are used to increase urine output, decrease swelling and shortness of breath. In accordance with ESC recommendations, patients should be instructed to inform their healthcare team or increase their diuretic dosage if they experience an increase in swelling or breathlessness or a sudden, unanticipated weight gain of more than 2 kg in three days. 2 Less focus has been placed on weight loss.
The authors of the current study hypothesised that the body weight of patients with heart failure could change during a heatwave. Professor Roubille explained: “When healthy people drink more fluids during hot weather, the body automatically regulates urine output. This does not apply to patients with heart failure because they take diuretics.”
Between 1 June and 20 September 2019, which included the two heat waves at the end of June and end of July, the study looked at the relationship between body weight and air temperature. 1,420 patients with chronic heart failure were included in the analysis. The average weight was 78 kg, the median age was 73 years, and 28% of the population were women. Information on weight and symptoms was remotely gathered using a national telemonitoring system. Every day, patients used a connected scale to weigh themselves; the connected scale sent measurements to the clinic automatically. By responding to questions on a personal device (such as a smartphone or tablet), patients were able to report daily symptoms like oedema, fatigue, breathlessness, and cough, with answers being sent automatically to the clinic. Data from were used to determine daily temperatures (at noon).
The relationship between patient weight, outside temperature on the same day, and outside temperature two days prior to the weight measurement was examined by the researchers. Weight decreases as temperature increases, indicating a strong correlation between the two variables. The two days before the weight measurement, temperatures were found to have the strongest correlation with weight.
Professor Roubille said: “The weight loss we observed during the heatwave was clinically relevant. Patients weighing 78 kg lost 1.5 kg in a short period of time. We were surprised to see that weight dropped with hot temperatures, as we had expected the opposite. For this reason, the telemonitoring system was programmed to alert clinicians when patients gained weight.”
He concludes by saying that with the expectation of more heatwaves, telemonitoring systems also need to alert clinicians of weight loss in heart failure patients. In addition, systems could notify patients losing weight that it may be due to the heat and they should contact their healthcare provider about reducing the dose of diuretics. For heart failure patients not monitored remotely, a good rule of thumb would be to contact a healthcare professional if weight drops by 2 kg during a heatwave for advice on adjusting diuretic medication. Reacting early should help us to prevent complications.
