Role of White Blood Cell Types in Heart Attacks

Two different white blood cell types play opposing roles in affecting irregular heartbeats after heart attack while neutrophils promote and macrophages protect.

Patients with heart disease are at a risk of experiencing a dangerous ’electrical storm’, which involves repeated episodes of an irregular heartbeat called ventricular tachycardia (VT).

Electric shock therapy has been used to treat VT following a heart attack, but the options to prevent its recurrence are limited. This research has been explained in the journal Nature Cardiovascular Research.

Investigations About Cardiac Conditions

New research led by investigators at Massachusetts General Hospital (MGH) reveals that two different white blood cell types influence ventricular tachycardia (VT) in the heart, suggesting that treatments that influence these cells may help reduce patients’ risk of sudden cardiac death.

Heart Attack - Overview
Heart attack is the death of the heart muscle due to loss of blood supply. Heart disease is the leading cause of death in the United States. Other names for heart attack include acute myocardial infarction, coronary thrombosis, and coronary occlusion.

‘Two different white blood cell types influence ventricular tachycardia in the heart suggesting that treatments that influence these cells may help reduce patients’ risk of sudden cardiac death.’

The work is based on the knowledge that cardiac conditions (such as heart attacks) that increase the risk of VT and other heartbeat irregularities lead to massive changes in the white blood cell populations surrounding the heart.

To study the mechanisms involved, MGH scientists developed a new research model. “It was believed that mice don’t get VT after a heart attack, but we discovered a surprisingly simple trick to induce it—feeding mice food with low potassium levels,” says senior author Matthias Nahrendorf, MD, PhD, an investigator in MGH’s Center for Systems Biology, a Professor of Radiology at Harvard Medical School and the Richard Moerschner Endowed MGH Research Institute Chair in Men’s Health.

“This is a major step forward because now we can study how different white blood cell subclasses influence heart rhythms. It is also clinically relevant because every fifth patient who experiences a heart attack has low blood potassium levels, and these patients are known to be particularly likely to develop heartbeat irregularities, or arrhythmia.”

Tips to Prevent Heart Attacks
Heart Attack occurs when the flow of oxygenated blood to heart muscles is hindered or stopped due to built-up of plaques in coronary arteries. Heart Attack is the No.1 killer among Indians.

The team’s experiments demonstrated that among the different white blood cell types, neutrophils promote ventricular tachycardia (VT) while macrophages protect against it. “Inflammatory neutrophils give rise to arrhythmia by compromising the electrical function of heart muscle cells called cardiomyocytes,” explains Nahrendorf.

“Macrophages, which take up debris, are protective, and deleting them gave rise to electrical storm in mice with low potassium levels who experienced a heart attack. Indeed, these mice were more likely to die from arrhythmia.”

What is a Heart Attack | How to Prevent Heart Attacks - Myocardial Infarction Smoking
Heart attack is the death of the heart muscle due to loss of blood supply. Simple guidelines to avoid heart attack are listed.

The findings indicate that additional research into the roles of white blood cells in irregular heartbeat could lead to new targeted therapies for irregular heart rhythms. This study has been funded by the NHLBI grants HL139598, HL142494, HL125428 and HL155097.

Source-Eurekalert