Of the various drugs that are used to treat respiratory diseases such as Asthma, oral steroids and theophylline that are most likely to cause an irregular heart rhythm, Spanish and US researchers report.

Numerous reports have linked respiratory medications with rhythm disorders, but data from broad-based studies is lacking, Dr. Consuelo Huerta, from Centro Espanol de Investigacion Farmacoepidemiologica in Madrid, and colleagues note in the medical journal Epidemiology.

To investigate this topic further, the researchers assessed respiratory drug use by 710 patients who experienced a heart rhythm irregularity and compared them with 5000 matched ‘controls.’

Inhaled steroid use had no effect on the risk of rhythm disorders, the researchers found. By contrast, an elevated risk was seen with oral steroid use and, to a lesser extent, short-term theophylline use.

Oral steroids were linked to several types of heart rhythm irregularity, and the team says it’s the first time this has been reported, as far as they know.

SOURCE: Epidemiology, May 2005.