Quinine Doesn't Mix Well With Heart Failure, Ischemic Disease

MUNICH – Treatment with quinine increased the mortality of heart failure patients who also had ischemic heart disease and received a beta-blocker by a statistically significant 16% in a study of more than 136,000 Danish heart failure patients during 1997-2010.

Although experts suggest that such use of quinine is not commonplace in the United States, the analysis of Danish patient and population registries showed that quinine was used in the treatment of 10% of HF patients. Quinine, an antimalarial drug, is often prescribed off-label to treat leg cramps, a common problem in patients with HF, Dr. Charlotte Andersson said at the annual congress of the European Society of Cardiology.

Mitchel L. Zoler/IMNG Medical Media

"Clinicians should attempt to find a treatment for leg cramps other than prescribing quinine" in patients with chronic HF, especially those with ischemic heart disease, said Dr. Andersson, a cardiologist at Gentofte Hospital in Copenhagen. She also expressed surprise that the dangerous interaction was greatest among patients who also received a beta-blocker drug.

"I would have expected patients on beta-blockers to be protected, but they weren’t, so probably conduction blocks [caused by quinine] are the problem," she said. "We found the highest risk of death during the first week of quinine treatment in patients with ischemic heart disease and on a beta-blocker, but if quinine was used chronically it still increased the risk."

"This is very interesting and important information," commented Dr. Marco Metra, a cardiologist at the University of Brescia, Italy. "The question is, what is the mechanism of the interaction of quinine and beta-blockers? We think that beta-blockers are protective against arrhythmias caused by QT prolongation. In this case, [the problem may be] bradycardia" caused by a beta-blocker that interacts with an effect from quinine, he suggested.

Dr. Andersson and her associates reviewed Danish national patient and population registry records collected during 1997-2010, which included 136,427 patients discharged from a hospital with a diagnosis of heart failure and who were alive at least 30 days following discharge. Their average age was 74 years, 47% were women, and 65% died during a median follow-up of 2.8 years.

The records showed that 14,306 patients (10%) had received at least one course of treatment with quinine, at a dosage of 100 or 200 mg/day. Overall, patients who received quinine had a 3% increased risk of death after adjustment for age and HF severity, which was estimated based on the dosage of loop diuretics they received. This increased risk fell just short of statistical significance.

However, further analysis showed that specific subgroups of HF patients faced a higher mortality threat from quinine treatment. Patients with ischemic heart disease (37% of the HF population) who received treatment with a beta-blocker (60% of the HF patients with ischemic heart disease) had the highest mortality when they received quinine, 16% higher than for similar patients who did not get quinine, after adjustment for age and HF severity. This meant that for every 38 patients with this clinical profile treated with quinine, 1 died.

Among HF patients with ischemic heart disease who did not receive a beta-blocker, the mortality rate was elevated by a statistically significant 8% among quinine users compared with quinine nonusers; 1 death occurred for every 46 patients in this category. And among HF patients who received a beta-blocker but who did not have ischemic heart disease, quinine treatment raised mortality by a statistically significant 9%, or 1 death for every 97 patients treated with quinine who fit this clinical profile.

Dr. Andersson said that she and her associates had no disclosures.

MUNICH – Treatment with quinine increased the mortality of heart failure patients who also had ischemic heart disease and received a beta-blocker by a statistically significant 16% in a study of more than 136,000 Danish heart failure patients during 1997-2010.

Although experts suggest that such use of quinine is not commonplace in the United States, the analysis of Danish patient and population registries showed that quinine was used in the treatment of 10% of HF patients. Quinine, an antimalarial drug, is often prescribed off-label to treat leg cramps, a common problem in patients with HF, Dr. Charlotte Andersson said at the annual congress of the European Society of Cardiology.

Mitchel L. Zoler/IMNG Medical Media

"Clinicians should attempt to find a treatment for leg cramps other than prescribing quinine" in patients with chronic HF, especially those with ischemic heart disease, said Dr. Andersson, a cardiologist at Gentofte Hospital in Copenhagen. She also expressed surprise that the dangerous interaction was greatest among patients who also received a beta-blocker drug.

"I would have expected patients on beta-blockers to be protected, but they weren’t, so probably conduction blocks [caused by quinine] are the problem," she said. "We found the highest risk of death during the first week of quinine treatment in patients with ischemic heart disease and on a beta-blocker, but if quinine was used chronically it still increased the risk."

"This is very interesting and important information," commented Dr. Marco Metra, a cardiologist at the University of Brescia, Italy. "The question is, what is the mechanism of the interaction of quinine and beta-blockers? We think that beta-blockers are protective against arrhythmias caused by QT prolongation. In this case, [the problem may be] bradycardia" caused by a beta-blocker that interacts with an effect from quinine, he suggested.

Dr. Andersson and her associates reviewed Danish national patient and population registry records collected during 1997-2010, which included 136,427 patients discharged from a hospital with a diagnosis of heart failure and who were alive at least 30 days following discharge. Their average age was 74 years, 47% were women, and 65% died during a median follow-up of 2.8 years.

The records showed that 14,306 patients (10%) had received at least one course of treatment with quinine, at a dosage of 100 or 200 mg/day. Overall, patients who received quinine had a 3% increased risk of death after adjustment for age and HF severity, which was estimated based on the dosage of loop diuretics they received. This increased risk fell just short of statistical significance.

However, further analysis showed that specific subgroups of HF patients faced a higher mortality threat from quinine treatment. Patients with ischemic heart disease (37% of the HF population) who received treatment with a beta-blocker (60% of the HF patients with ischemic heart disease) had the highest mortality when they received quinine, 16% higher than for similar patients who did not get quinine, after adjustment for age and HF severity. This meant that for every 38 patients with this clinical profile treated with quinine, 1 died.

Among HF patients with ischemic heart disease who did not receive a beta-blocker, the mortality rate was elevated by a statistically significant 8% among quinine users compared with quinine nonusers; 1 death occurred for every 46 patients in this category. And among HF patients who received a beta-blocker but who did not have ischemic heart disease, quinine treatment raised mortality by a statistically significant 9%, or 1 death for every 97 patients treated with quinine who fit this clinical profile.

Dr. Andersson said that she and her associates had no disclosures.

MUNICH – Treatment with quinine increased the mortality of heart failure patients who also had ischemic heart disease and received a beta-blocker by a statistically significant 16% in a study of more than 136,000 Danish heart failure patients during 1997-2010.

Although experts suggest that such use of quinine is not commonplace in the United States, the analysis of Danish patient and population registries showed that quinine was used in the treatment of 10% of HF patients. Quinine, an antimalarial drug, is often prescribed off-label to treat leg cramps, a common problem in patients with HF, Dr. Charlotte Andersson said at the annual congress of the European Society of Cardiology.

Mitchel L. Zoler/IMNG Medical Media

"Clinicians should attempt to find a treatment for leg cramps other than prescribing quinine" in patients with chronic HF, especially those with ischemic heart disease, said Dr. Andersson, a cardiologist at Gentofte Hospital in Copenhagen. She also expressed surprise that the dangerous interaction was greatest among patients who also received a beta-blocker drug.

"I would have expected patients on beta-blockers to be protected, but they weren’t, so probably conduction blocks [caused by quinine] are the problem," she said. "We found the highest risk of death during the first week of quinine treatment in patients with ischemic heart disease and on a beta-blocker, but if quinine was used chronically it still increased the risk."

"This is very interesting and important information," commented Dr. Marco Metra, a cardiologist at the University of Brescia, Italy. "The question is, what is the mechanism of the interaction of quinine and beta-blockers? We think that beta-blockers are protective against arrhythmias caused by QT prolongation. In this case, [the problem may be] bradycardia" caused by a beta-blocker that interacts with an effect from quinine, he suggested.

Dr. Andersson and her associates reviewed Danish national patient and population registry records collected during 1997-2010, which included 136,427 patients discharged from a hospital with a diagnosis of heart failure and who were alive at least 30 days following discharge. Their average age was 74 years, 47% were women, and 65% died during a median follow-up of 2.8 years.

The records showed that 14,306 patients (10%) had received at least one course of treatment with quinine, at a dosage of 100 or 200 mg/day. Overall, patients who received quinine had a 3% increased risk of death after adjustment for age and HF severity, which was estimated based on the dosage of loop diuretics they received. This increased risk fell just short of statistical significance.

However, further analysis showed that specific subgroups of HF patients faced a higher mortality threat from quinine treatment. Patients with ischemic heart disease (37% of the HF population) who received treatment with a beta-blocker (60% of the HF patients with ischemic heart disease) had the highest mortality when they received quinine, 16% higher than for similar patients who did not get quinine, after adjustment for age and HF severity. This meant that for every 38 patients with this clinical profile treated with quinine, 1 died.

Among HF patients with ischemic heart disease who did not receive a beta-blocker, the mortality rate was elevated by a statistically significant 8% among quinine users compared with quinine nonusers; 1 death occurred for every 46 patients in this category. And among HF patients who received a beta-blocker but who did not have ischemic heart disease, quinine treatment raised mortality by a statistically significant 9%, or 1 death for every 97 patients treated with quinine who fit this clinical profile.

Dr. Andersson said that she and her associates had no disclosures.