Millions of people with heart failure could ultimately benefit from life-saving cardiac resynchronization therapy (CRT) if a new trial just underway proves that it helps.
Up to 70% of the 5 million Americans with congestive heart failure — those with narrow QRS — are currently treated with medication only and the prognosis for these patients is rarely good. In a new study, EchoCRT (Echocardiography-guided Cardiac Resynchronization Therapy), investigators are trying to determine if these patients could benefit from CRT.
The first implantation of Biotronik's (Berlin/Lake Oswego, Oregon) Lumax CRT was performed this week at Ohio State University Medical Center (Columbus) as part of the 1,250-patient trial.
EchoCRT is intended to demonstrate that optimal medical therapy plus CRT reduces all-cause mortality or first hospitalization for worsening heart failure in the study population compared to optimal medical therapy alone.
"Originally the trials to get CRT devices approved in the market in Europe and U.S. were based on patients with wide QRS with an electrocardiogram (ECG) anomaly that shows longer-than-normal ventricular activity (QRS width = 120-130 ms). They represent only 30% of all subjects with chronic heart failure," Kevin Mitchell, Biotronik VP of clinical studies, told Diagnostics & Imaging Week.
He added, "Years ago when CRT started, the studies were based on the idea that if you have mechanical synchrony you also have electrical. Now we know that there isn't a close correlation between electrical and mechanical defects."
Mitchell said it's the largest, prospective, randomized, double-blind, international, multicenter clinical trial of its kind, with 125 investigational centers worldwide, including sites in Australia, Canada, Israel, Europe and the U.S.
CRT is a treatment for heart failure patients experiencing conduction abnormalities and a lack of synchronization in the two ventricles. An implantable cardioverter defibrillator (ICD) is surgically inserted to constantly monitor heart rate and rhythm. When it detects a rapid, life-threatening heart rhythm, the ICD delivers a large electrical impulse to the heart muscle to restore normal rhythm.
The EchoCRT study will randomize patients with heart failure, already receiving current standard pharmacological therapy, with a narrow QRS width (less than 130 ms) and echocardiographic evidence of left ventricular dyssynchrony.
"All of the patients enrolled will receive the device. Half will be programmed to CRT therapy on and the others will have it programmed off," Mitchell said.
The Lumax also includes Biotronik home monitoring. That data will be used in a pre-specified analysis to evaluate the frequency and duration of irregular heart rhythms. Patients will be followed for a mean duration of 24 months.
In recognition of its substantial clinical benefits, CRT is recommended in both the European Society of Cardiology guidelines and in the American College of Cardiology/American Heart Association guidelines for the diagnosis and treatment of chronic heart failure. But those guidelines have limited the application of CRT to patients with a QRS width of = 120 ms. EchoCRT will assess whether some of the remaining 70% of heart failure patients with "narrow QRS" could benefit from CRT therapy.
EchoCRT was designed under guidance from an executive steering committee of 11 academic specialists in electrophysiology, heart failure and echocardiography who considered earlier studies in developing the EchoCRT design.
"Chronic heart failure is associated with a poor prognosis with considerably shortened survival and repeated hospitalizations," said Frank Ruschitzka, MD, of the University of Zürich, executive committee co-chairman and international co-principal investigator of EchoCRT. "The vast majority of patients with heart failure present with a narrow QRS and do not currently receive CRT. The EchoCRT trial will test the hypothesis whether CRT improves outcomes in this large subset of heart failure patients."
News of the initiation of the EchoCRT study comes on the eve of the European Society of Cardiology Congress in Munich, which starts this weekend. That event attracts more than 25,000 cardiologists annually.