TACHYCARDIA INCREASES CANCER MORTALITY RISK

Among cancer patients who have tachycardia but who have not had a medical condition that is associated with tachycardia, such as pulmonary disease or thyroid disease, overall mortality risk is markedly increased. That increased risk may reflect the extra strain placed on the body by their cancer, say US researchers.

Tochi M. Okwuosa, DO, director of the cardio-oncology program at Rush University Medical Center, Chicago, Illinois, studied more than 620 cancer patients, of whom 50 were found to have explained sinus tachycardia.

After taking into account numerous potential confounding factors, the investigators found that for cancer patients with tachycardia, overall mortality risk was approximately three times that of other cancer patients.

The results were presented at the Advancing the Cardiovascular Care of the Oncology Patient conference on January 25.

Study coauthor Mohamad Hemu, MD, also from Rush University Medical Center, said in a statment: "Tachycardia is a secondary process to an underlying disease and reflective of significant multisystem organ stress and disease in cancer patients.

"As a result, the most important initial step is to figure out what is causing the tachycardia," he continued. "Reversible causes like dehydration and infections should be ruled out. Additionally, cardiopulmonary processes such as pulmonary embolism and other arrhythmias must be taken into consideration.

"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," Hemu commented.

While calling for more studies, Okwuosa said that their study "shows that tachycardia is a strong prognosticator regardless of cancer type."

Tachycardia is a strong prognosticator regardless of cancer type. Dr Tochi Okwuosa

"That's why it is critically important to be co-managing both cancer and heart conditions to ensure patients receive the most effective treatment possible."

Speaking to Medscape Medical News, Okwuosa explained that their hypothesis is that tachycardia reflects the metabolic strain placed on the patient's system by the cancer.

As an analogy, she said that when healthy people run, their heart rate goes up, and they in effect become tachycardic.

"Generally what happens is your body speeds up your heart rate in order to supply more blood to your tissues when you're running, because your tissues need that blood flow," she said.

"Well, in somebody who's very sick and they have a systemic issue going on that's affecting their entire body, such as cancer, I feel the sicker they are, the more their cells are affected, the more the rest of the body is affected, and so the higher the demand to try to meet the metabolic needs of the cancer."

Okwuosa said that while they await the results of further studies on the effectiveness of beta blockers in treating unexplained tachycardia in cancer patients, "one of the ultimate questions is, What kind of advice do you have for patients that are tachycardic and are going through cancer treatment?

"In all honesty, it's hard to figure out what's the right answer. Do you tell the patient this suggests that you're really sick and this suggests that there's a high chance that you're going to die?

"No, I think that most of us would not do that, especially since this is new data that's coming out," she said.

On the other hand, Okwuosa suggested that, although cancer patients may not be able to perform the recommended 150 minutes of exercise per week, they should try to walk or cycle as much as possible to condition their bodies.

"We know that, in normal patients, the more you exercise, the slower the heart rate, because there's increased vagal tone, but the kind of advice to give cancer patients becomes more difficult, just because they're really sick," she said.

"But we still encourage them to condition themselves," she added.

Approached for comment, Gordon F. Tomaselli, MD, Albert Einstein College of Medicine, New York City, said that, once the major causes of tachycardia have been ruled out, "I really do think you need to extensively look at the heart to make sure that there's not something that's a potential complication that in fact may get worse and at the very least be treated."

He added, "It's not at all surprising to me...that unexplained tachycardia is an adverse predictor of outcome, and there may be many reasons for it."

Tomaselli emphasized that it is "increasingly important" that when a cancer patient is about to start treatment, "you make sure that you understand the underlying state of their heart and vasculature.

"Nobody will thank you if you get successful treatment for a cancer but it leaves you with really significant cardiovascular disease that's going to limit your life expectancy and, more importantly, may on a day-to-day basis make the morbidity of the treatment pretty high," he added.

Study Details

Okwuosa and colleagues conducted a retrospective case-control analysis of 622 patients with lung cancer, leukemia, lymphoma, or multiple myeloma who underwent treatment from 2008 to 2016.

Tachycardia was defined as a heart rate ≥100 bpm at three or more clinical visits within 1 year of the cancer diagnosis.

After excluding patients with a history of pulmonary embolism, thyroid 

/flutter, and heart rate >180 bpm, they identified 50 patients with unexplained tachycardia and 572 control patients.

For the 622 cancer patients who were included in the study, the mean age was 70 years, 60.5% were women, and 76.4% were white.

Of all cancer patients, 69.4% had American Joint Committee on Cancer stage IV disease, and 43.0% had lung cancer.

After adjusting for age, race, albumin, hemoglobin

< .01).

In a second model that adjusted for age, race, albumin, beta blockers, aspirin, coronary artery disease, stroke, diabetes, smoking, radiation, and athracyclines, tachycardia was associated with overall mortality at a hazard ratio of 2.8 (P < .001).

Future Plans

The researchers are planning to conduct an analysis to compare the outcomes of the tachycardia patients who received beta blockers and those who did not, although Okwuosa pointed out that the number of patients in these groups is relatively small.

She said: "We have just a few, 50 something, cancer patients all together, so this would be something that would be good in a larger study to see if we use beta blockers, that makes a difference in terms of mortality in the patients that are tachycardic."

Okwuosa continued: "That's something that's in the pipeline, something that we're still analyzing and something that we're thinking of obtaining funding for to study in a prospective manner in a randomized controlled study."

Tomaselli agreed that if the tachycardia "is a reflection of relatively minor but existing heart muscle weakness," owing, for example, to cancer treatment, "treatment with beta blockers might in fact improve outcomes."

He added: "This cohort is complicated by the fact that that they've had a primary malignancy, and a primary malignancy that may be the more important driver of overall mortality and outcome at the end of the day, but if in fact it's related to the heart, I think beta blockers are probably a good treatment option."

No funding for the study has been reported. The investigators have disclosed no relevant financial relationships. 

Advancing the Cardiovascular Care of the Oncology Patient: Abstract 21. Presented January 25, 2019.