乌鸦传媒

WASHINGTON -- Unexplained sinus tachycardia was associated with a significantly higher rate of all-cause mortality in patients with cancer, a retrospective study found.

Among over 600 patients, the mortality rate was two to three times greater in those with an unexplained heart rate ≥100 beats per minute (bpm) on three or more clinic visits within a year of their cancer diagnosis, Mohamad Hemu, MD, and colleagues from Rush University Medical Center in Chicago, reported here at the conference on Advancing the Cardiovascular Care of the Oncology Patient.

At 10 years, 62% of those with unexplained tachycardia had died compared with 22.9% of those with a normal heart rhythm.

The results were consistent across two different models that adjusted for age, race, beta-blocker use, and other factors: the first model also adjusted for hemoglobin, type of cancer, kidney disease, and anticoagulation use (HR 3.1, 95% CI 1.8-5.1, P<0.001); the second also adjusted for aspirin use, coronary artery disease, stroke, diabetes, and treatment with radiation or anthracyclines (HR 2.8, 95% CI 1.7-4.6, P<0.001).

"After we ruled out any other cause of the tachycardia, the pattern I started to notice was that these patients, especially those who had persistent tachycardia, were the ones that we heard were in hospice shortly after or who were gone within a year or two, so we decided to study this," senior co-author Tochi Okwuosa, DO, told 乌鸦传媒.

Patients were identified as having unexplained sinus tachycardia when a history of pulmonary embolism, ejection fraction <50%, thyroid dysfunction, or atrial fibrillation was ruled out.

"My suspicion is that this [unexplained] tachycardia is the body's response to being stressed out by the malignancy, so it's the illness itself that is causing the tachycardia, and it is not a good prognostic sign," she added.

Investigators carried out their case-control study in 622 cancer patients treated at Rush University Medical Center for lung cancer (43%), leukemia, lymphoma, or multiple myeloma from 2008 to 2016. The mean age of the cohort was 70 years, just over 60% were women, and almost 70% had stage IV cancer.

Those in the sinus tachycardia group had baseline higher rates of diabetes (30.0% vs 19.1% with controls) and renal disease (46.0% vs 17.1%, respectively), and 48.0% in this group were on beta blockers at baseline compared with 31.5% in the control group.

"We did correct for the fact that these patients were on beta blockers so this did not influence our results," Okwuosa noted.

Hemu stressed that the most important initial step when patients such as these present is to determine what is causing the tachycardia. "Reversible causes like dehydration and infections should be ruled out," he said in a statement, adding that other arrhythmias and even pulmonary embolism must be considered as well. "Once these and all other causes of tachycardia are ruled out, then it is more likely that sinus tachycardia is a marker of poorer prognosis in these patients."

Okwuosa said she encourages her patients to walk in the hopes that even small increments of exercise might help with conditions of the heart.

"Many of these patients are tired so I tell them, 'Even if you are tired, just try to walk 5 or 10 minutes, then rest, then try another 5 to 10 minutes, but try to walk every day,'" she said. "And I tell patients that exercise has been shown to be good for cancer patients even when they are going through treatment, so I encourage patients to condition themselves by walking."

Results of a meta-analysis in cancer patients found that exercise, in fact, doubled peak oxygen consumption compared with no exercise, suggesting that exercise may improve heart health in these patients. However, most of the trials included in the meta-analysis consisted of higher-intensity exercise sessions that lasted from 30 to 45 minutes and performed 3 times a week.