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A new study has found the number of people who survive after suffering a cardiac arrest outside a hospital drops significantly if the pause between stopping CPR and using a defibrillator to administer an electric shock is longer than 20 seconds.

The number of people who survive rises significantly if the pause is less than 10 seconds.

“If your pre-shock pause is over 20 seconds, the chances of surviving to reach a hospital, be treated and be discharged are 53 per cent less than if the pause is less than 10 seconds.” said Dr. Sheldon Cheskes, lead author of the study published today in Circulation: Journal of the American Heart Association.

Looking at the data another way, Cheskes said researchers found an 18 per cent drop in the number of patients surviving to be discharged from hospital for every five second increase in the pause between CPR and providing a shock with a defibrillator.

Cheskes is a collaborative investigator at the Li Ka Shing Knowledge Institute of St. Michael’s Hospital as well as medical director for the Sunnybrook Osler Centre for Prehospital Care.

Cheskes said he hoped the findings would encourage paramedics to minimize any interruption in CPR. He’d also like to see manufacturers produce new software to shorten the length of time it takes to analyze a patient’s heart rhythm and charge the defibrillator before delivering a shock. He said more paramedics should be trained to use defibrillators on manual mode rather than automatic to also speed up those two steps.

The researchers examined the files of 815 patients who suffered an out-of-hospital cardiac arrested between December 2005 and June 2007. The data was gathered by the Resuscitation Outcomes Consortium (ROC), a group of 11 Canadian and U.S. regional clinical centres including more than 200 EMS/fire agencies that carry out research related to cardiac arrest resuscitation and life-threatening traumatic injury. The Toronto centre, Rescu, is based at St. Michael’s.

ROC’s main funders include the Heart and Stroke Foundation of Canada and the Canadian Institutes of Health Research.

“Currently in Canada, less than five per cent of people survive an out-of hospital cardiac arrest,” said Manuel Arango, director of health policy for the Heart and Stroke Foundation. “New techniques from the Resuscitation Outcomes Consortium have the potential to dramatically increase these odds. To date, ROC research has tripled survival rates in their test communities − revolutionizing how healthcare professionals do CPR in the field.”

“The Canadian Institutes of Health Research are proud to support this resuscitation study,” said Dr. Jean Rouleau, Scientific Director of the Institute of Circulatory and Respiratory Health. “When these findings are translated into practice, they will have the potential to save countless lives in Canada and throughout the world.”

Cheskes said previous smaller studies showed the length of time between CPR and delivering an electric shock affected whether the patient’s heart rhythm was restored. This was the first study to show it impacted how many not only made it to the hospital for treatment but also survived and were discharged.

The study found the length of time between delivering a shock and resuming CPR had no significant impact on survival rates.

An invention by Rice University bioengineering students in collaboration with the Texas Heart Institute (THI) is geared toward giving immediate second chances to arrhythmia victims headed toward cardiac arrest.

For their capstone design project, a team of Rice seniors created a unique pad system for automated external defibrillators (AEDs), common devices that can shock a victim’s heart back into a proper rhythm in an emergency.

Often, the first shock doesn’t reset a heart and the procedure must be repeated, but the sticky pads on the chest must first be repositioned. The pads need to be in the right location to send current through the heart, and someone with no experience who tries to provide aid might miss the first time.

The Second-Chance AED Pads let rescuers try again without losing valuable time to remove the pads from the victim’s chest. The pads incorporate three electrodes, two in a single pad with an A/B switch attached, and a third in its own pad.

If one shock doesn’t restart the patient’s heart, flipping the switch will change the jolt’s path, just a little bit, for the second attempt.

The pads were developed by students on the DefibTaskForce — Lisa Jiang, Joanna Nathan, Justin Lin, Carl Nelson and Brad Otto — in tandem with Mehdi Razavi, director of electrophysiology clinical research at THI, and their adviser, Renata Ramos, a Rice lecturer in bioengineering.

The potential for their project was clear from the beginning. “We did some calculations that suggested we could save at least 13,000 lives per year,” Otto said. “Cardiac defibrillation is very time-sensitive. Thirty seconds can be the difference between life and death in a lot of situations. The time it takes to flip the switch is negligible compared with the time it takes to remove the pads, shave and prep a new area on the body, reapply the pads and administer another shock. And a layman might not even know to try a second position.”

Rather than try to build a new type of AED, the team decided early on that it was enough to simply design new pads that would fit devices that are already in use. Manufacturers generally require AED pads be replaced every two years, which provides a ready market for the students’ invention. “But well over 100,000 AED units are produced every year, so even if our pads are only paired with new AEDs, we have a significant market,” Lin said.

Getting the instructions right turned out to be just as important as the device itself and required a lot of illustrative trial and error. In tests for the final version at Rice’s Oshman Engineering Design Kitchen, the team recruited students with no experience using an AED to shock a medical mannequin back to life. “We had 100 percent of the testers place the pads correctly, showing it was very intuitive to use,” Jiang said.

All five team members, along with Razavi and Ramos, are listed on the provisional patent. They hope an AED manufacturer will pick up the rights to the Second-Chance pads for clinical trials and ultimately FDA approval.

A video of students demonstrating the Second-Chance pads is available at http://www.youtube.com/watch?v=FYChUo1oJM4

Researchers Pinpoint Patients Who Receive Greatest Benefit from Heart Failure Treatment

March 01, 2011

Mild heart failure patients with a particular condition that results in disorganized electrical activity throughout the heart benefit substantially from cardiac resynchronization therapy with defibrillator (CRT–D), according to a study published in the American Heart Association journal Circulation.

In patients with the condition, known as left bundle branch block or LBBB, CRT-D therapy reduced heart failure progression and the risk of ventricular tachyarrhythmias, fast and potentially life-threatening heart rhythms. Heart failure patients without LBBB did not receive any benefit from the therapy.

The analysis, based on the major study which tested the device – the MADIT-CRT trial – led the FDA to extend the approval of the CRT-D in September 2010 to patients with mild heart failure and LBBB to prevent progression to advanced heart failure. The device, developed by Boston Scientific, was originally approved to treat patients with severe heart failure.

Cardiac resynchronization therapy with defibrillator (CRT–D)

“This study allowed us to identify the specific set of patients that receive the greatest benefit from this device,” said Wojciech Zareba, M.D., Ph.D., lead study author and director of the Heart Research Follow-up Program at the University of Rochester Medical Center. “Our analysis highlights the fact that this therapy is not equally effective in all mild heart failure patients and was the basis of the FDA’s approval of the therapy only in patients with left bundle branch block.”

Zareba’s team found that patients with LBBB who received CRT-D therapy had a significant 53 percent reduction in the risk of a heart failure event, such as being hospitalized with heart failure symptoms, or death, compared to LBBB patients who only received an implantable cardioverter defibrillator (ICD). The risk of ventricular tachyarrhythmias was also considerably less in LBBB patients with CRT-D..

CRT-D therapy combines an ICD, which senses dangerous abnormal heart rhythms and attempts to shock the heart back into a normal rhythm, with cardiac resynchronization therapy (CRT), which coordinates the beating of the heart so it can pump blood throughout the body more effectively.

The study included 1,817 patients and researchers analyzed electrocardiograms – maps of the heart’s electrical activity – to determine which patients had electrical disturbances and what type. Seventy percent of study participants had LBBB. LBBB patients were more often female and had higher rates of non-ischemic heart disease, a disorder typically characterized by inflammatory scarring of the heart muscle.

Study authors evaluated the effects of CRT-D versus ICD therapy in patients with and without LBBB. They found that in LBBB patients, CRT-D therapy effectively prevented deterioration of the heart, otherwise known as cardiac remodeling, by preventing enlargement of the heart with more effective contraction of the heart.

“We believe this therapy is so effective in patients with LBBB because their hearts don’t contract in a synchronous way, rather, the pumping action is quite out of sync,” noted Zareba. “CRT-D therapy paces the heart and makes these patients much better very quickly.”

Beyond mild heart failure patients, the results are leading experts to rethink current guidelines recommending the use of CRT-D therapy for all advanced heart failure patients. In this age of personalized medicine, as treatments are continually directed towards subsets of patients with particular characteristics or biologic markers, the group of advanced heart failure patients that receive CRT-D therapy may be narrowed to those with LBBB, as well.

The MADIT-CRT trial, led by Arthur J. Moss, M.D., cardiologist at the University of Rochester Medical Center, was supported by a research grant from Boston Scientific to the University of Rochester. The sub-analysis, led by Zareba, was also sponsored by Boston Scientific.

Therapy to prevent heart failure more effective in women than men

Never before has a therapy proven more beneficial for women than men in preventing heart disease – until now.

A new study, published today in the Journal of the American College of Cardiology, found that women receive a significantly greater benefit – a 70 percent reduction in heart failure and a 72 percent reduction in death – from cardiac resynchronization therapy with defibrillator (CRT-D) than men.

“In prior cardiac studies, men and women generally received similar benefit from preventive medical therapy,” said cardiologist Arthur J. Moss, M.D., professor of Medicine at the University of Rochester Medical Center and lead author of the study. “Our finding was unexpected, but extremely important because this is the only heart treatment that is clearly better in women than men.”

Historically, heart disease has been dominated by its association with men. But, thanks to successful awareness campaigns in recent years, such as the American Heart Association’s Go Red for Women initiative, women have started to take note of their risks and take action to protect their health.

On all fronts, women receiving CRT-D therapy to prevent heart failure progression had significantly better outcomes than men receiving the therapy. Reduction of heart failure in females was twice that of males – 70 percent versus 35 percent.

In women with mild heart failure, CRT-D therapy effectively prevented deterioration of the heart, otherwise known as cardiac remodeling, by preventing enlargement of the heart with more effective contraction of the heart.

Study authors investigated the reasons for the significantly better result in women than men. Women in the study were more likely to have non-ischemic heart disease, a disorder typically characterized by inflammatory scarring of the heart muscle, while men had a greater likelihood of ischemic heart disease – otherwise known as coronary artery disease – where narrowed arteries restrict the flow of blood and oxygen to the heart. Additionally, more women had left bundle branch block, a condition that results in disorganized electrical activity throughout the heart.

Because left bundle branch block and non-ischemic heart disease lead to diffuse, as opposed to localized, heart problems, study authors reasoned women were more responsive to CRT-D therapy, a treatment that strengthens the overall mechanical pumping action of the heart and coordinates the heart’s electrical activity.

“It’s not that men did poorly in the trial, but rather, women had really fantastic results, likely due to they type of heart disease we see more commonly in women,” noted Moss.

The CRT-D device, developed by Boston Scientific, was originally approved to treat patients with severe heart failure. In September 2010, the Food and Drug Administration extended the approval of the Boston Scientific device to patients with mild heart failure to prevent progression to advanced heart failure. With the new indication, nearly 4 million more Americans are candidates for treatment with the CRT-D.

CRT-D therapy combines an implantable cardioverter defibrillator (ICD), which is designed to prevent sudden, rhythm-related cardiac death, with cardiac resynchronization therapy (CRT), which improves heart function with a reduction in heart failure and associated symptoms.

The study is a sub-analysis of the MADIT-CRT trial that was published in 2009 in the New England Journal of Medicine. The study involved 1,820 participants from 110 medical centers in the United States, Canada and Europe and compared the effectiveness of CRT-D versus ICD therapy in reducing heart failure and death during four and one-half years of follow-up. Twenty-five percent, or 453 of the study participants, were female.

Currently, 42 million American women are living with heart disease. It is the leading killer of women in the United States, each year claiming more women than men. In 2005, cardiovascular disease claimed the lives of more than 450,000 women, while all forms of cancer claimed the lives of approximately 265,000 women, according to the American Heart Association.

The study was a joint effort between Boston Scientific and the University of Rochester Medical Center, with the participation of patients from medical centers throughout the world. Aysha Arshad, M.D., and Jonathan Steinberg, M.D., from St. Luke’s and Roosevelt Hospitals and Columbia University College of Physicians and Surgeons in New York City are the major co-authors of the article. Moss holds no stock in any device company, has never been a member of any corporate speakers’ bureau, and since Dec. 1, 2008, has chosen not to accept honoraria from Boston Scientific for any professional activity.

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