Best CRT outcomes with LBBB and prolonged QRS

In a large, real-world population of patients who underwent cardiac resynchronization therapy-defibrillator implantation, those who had left bundle-branch block and a QRS duration of 150 ms or more had the best outcomes, according to a report published online August 13 in JAMA.

Patients with left bundle-branch block (LBBB) and a long QRS duration had the lowest mortality risk and the lowest rates of all-cause, cardiovascular, and heart failure readmissions, while patients without LBBB and with a QRS duration of 120-149 ms "consistently had the greatest risks of adverse outcomes," said Dr. Pamela N. Peterson of the Denver Health Medical Center and her associates.

These findings "are particularly notable, given that both LBBB and prolonged QRS duration have been shown to be independent predictors of mortality among patients with left ventricular systolic dysfunction without CRT [cardiac resynchronization therapy]," the investigators said.

The results support the use of QRS morphology and duration to identify which patients can expect the greatest benefit from CRT-D implantation, they noted.

Even though current guidelines recommend selecting patients for CRT based primarily on their QRS morphology and duration, these recommendations are based primarily on meta-analyses and subgroup analyses of clinical trials that only considered these two factors separately. The only study to evaluate the combination of QRS morphology and duration "did not assess meaningful patient outcomes," so the utility of these recommendations in real-world practice hasn’t been clear, Dr. Peterson and her colleagues wrote.

They examined the issue using information from the National Cardiovascular Data Registry’s ICD database. They assessed outcomes in 24,169 Medicare fee-for-service patients who underwent CRT-D implantation in a 3-year period, between 2006 and 2009.

Only patients with a QRS interval of 120 ms or longer were included. The mean age of these study subjects was 75 years. Most (90%) were white and 68% were men.

Comorbid conditions were common, including hypertension (78% of patients), ischemic heart disease (65%), diabetes (38%), atrial fibrillation or flutter (32%), and chronic lung disease (23%). The majority of patients (61%) had not had coronary artery bypass graft surgery.

Most patients (83%) had New York Heart Association class III heart failure symptoms. A total of 67% had LBBB, and 55% had a QRS duration of 150 ms or longer.

Overall mortality was 0.8% at 30 days, 9.2% at 1 year, and 25.9% at 3 years. Overall rates of all-cause readmission were 10.2% at 30 days and 43.3% at 1 year. Rates of heart failure readmission were 2.2% at 30 days and 12.3% at 1 year.

In an unadjusted analysis of the data, rates of all adverse outcomes were significantly lower among patients who had LBBB and a QRS duration of 150 ms or more, the investigators said (JAMA 2013; 310:617-26; [doi:10.1001/jama.2013.8641]).

After the data were adjusted to account for numerous demographic and clinical factors, this difference remained robust. Patients who had LBBB and a QRS duration of 150 ms or greater had a 3-year mortality risk of 21%, compared with 27% for those with LBBB and QRS duration of 120-149 ms. Those with no LBBB and QRS duration of 150 ms or greater had an adjusted 3-year mortality risk of 31%), and patients with no LBBB and QRS durations of 120-149 ms had a 3-year risk of 32%. All differences were significant.

Patients with no LBBB and a long QRS duration, those with LBBB and a short QRS duration, and those with no LBBB and a short QRS duration consistently had higher risks of all adverse outcomes.

"Our real-world data add to the increasing body of evidence that patients with LBBB have better outcomes after CRT," Dr. Peterson and her associates said.

This study was supported by the U.S. Agency for Healthcare Research and Quality and the American College of Cardiology Foundation. Dr. Peterson reported serving as a consultant for Merck, and her associates reported numerous ties to industry sources.

In a large, real-world population of patients who underwent cardiac resynchronization therapy-defibrillator implantation, those who had left bundle-branch block and a QRS duration of 150 ms or more had the best outcomes, according to a report published online August 13 in JAMA.

Patients with left bundle-branch block (LBBB) and a long QRS duration had the lowest mortality risk and the lowest rates of all-cause, cardiovascular, and heart failure readmissions, while patients without LBBB and with a QRS duration of 120-149 ms "consistently had the greatest risks of adverse outcomes," said Dr. Pamela N. Peterson of the Denver Health Medical Center and her associates.

These findings "are particularly notable, given that both LBBB and prolonged QRS duration have been shown to be independent predictors of mortality among patients with left ventricular systolic dysfunction without CRT [cardiac resynchronization therapy]," the investigators said.

The results support the use of QRS morphology and duration to identify which patients can expect the greatest benefit from CRT-D implantation, they noted.

Even though current guidelines recommend selecting patients for CRT based primarily on their QRS morphology and duration, these recommendations are based primarily on meta-analyses and subgroup analyses of clinical trials that only considered these two factors separately. The only study to evaluate the combination of QRS morphology and duration "did not assess meaningful patient outcomes," so the utility of these recommendations in real-world practice hasn’t been clear, Dr. Peterson and her colleagues wrote.

They examined the issue using information from the National Cardiovascular Data Registry’s ICD database. They assessed outcomes in 24,169 Medicare fee-for-service patients who underwent CRT-D implantation in a 3-year period, between 2006 and 2009.

Only patients with a QRS interval of 120 ms or longer were included. The mean age of these study subjects was 75 years. Most (90%) were white and 68% were men.

Comorbid conditions were common, including hypertension (78% of patients), ischemic heart disease (65%), diabetes (38%), atrial fibrillation or flutter (32%), and chronic lung disease (23%). The majority of patients (61%) had not had coronary artery bypass graft surgery.

Most patients (83%) had New York Heart Association class III heart failure symptoms. A total of 67% had LBBB, and 55% had a QRS duration of 150 ms or longer.

Overall mortality was 0.8% at 30 days, 9.2% at 1 year, and 25.9% at 3 years. Overall rates of all-cause readmission were 10.2% at 30 days and 43.3% at 1 year. Rates of heart failure readmission were 2.2% at 30 days and 12.3% at 1 year.

In an unadjusted analysis of the data, rates of all adverse outcomes were significantly lower among patients who had LBBB and a QRS duration of 150 ms or more, the investigators said (JAMA 2013; 310:617-26; [doi:10.1001/jama.2013.8641]).

After the data were adjusted to account for numerous demographic and clinical factors, this difference remained robust. Patients who had LBBB and a QRS duration of 150 ms or greater had a 3-year mortality risk of 21%, compared with 27% for those with LBBB and QRS duration of 120-149 ms. Those with no LBBB and QRS duration of 150 ms or greater had an adjusted 3-year mortality risk of 31%), and patients with no LBBB and QRS durations of 120-149 ms had a 3-year risk of 32%. All differences were significant.

Patients with no LBBB and a long QRS duration, those with LBBB and a short QRS duration, and those with no LBBB and a short QRS duration consistently had higher risks of all adverse outcomes.

"Our real-world data add to the increasing body of evidence that patients with LBBB have better outcomes after CRT," Dr. Peterson and her associates said.

This study was supported by the U.S. Agency for Healthcare Research and Quality and the American College of Cardiology Foundation. Dr. Peterson reported serving as a consultant for Merck, and her associates reported numerous ties to industry sources.

In a large, real-world population of patients who underwent cardiac resynchronization therapy-defibrillator implantation, those who had left bundle-branch block and a QRS duration of 150 ms or more had the best outcomes, according to a report published online August 13 in JAMA.

Patients with left bundle-branch block (LBBB) and a long QRS duration had the lowest mortality risk and the lowest rates of all-cause, cardiovascular, and heart failure readmissions, while patients without LBBB and with a QRS duration of 120-149 ms "consistently had the greatest risks of adverse outcomes," said Dr. Pamela N. Peterson of the Denver Health Medical Center and her associates.

These findings "are particularly notable, given that both LBBB and prolonged QRS duration have been shown to be independent predictors of mortality among patients with left ventricular systolic dysfunction without CRT [cardiac resynchronization therapy]," the investigators said.

The results support the use of QRS morphology and duration to identify which patients can expect the greatest benefit from CRT-D implantation, they noted.

Even though current guidelines recommend selecting patients for CRT based primarily on their QRS morphology and duration, these recommendations are based primarily on meta-analyses and subgroup analyses of clinical trials that only considered these two factors separately. The only study to evaluate the combination of QRS morphology and duration "did not assess meaningful patient outcomes," so the utility of these recommendations in real-world practice hasn’t been clear, Dr. Peterson and her colleagues wrote.

They examined the issue using information from the National Cardiovascular Data Registry’s ICD database. They assessed outcomes in 24,169 Medicare fee-for-service patients who underwent CRT-D implantation in a 3-year period, between 2006 and 2009.

Only patients with a QRS interval of 120 ms or longer were included. The mean age of these study subjects was 75 years. Most (90%) were white and 68% were men.

Comorbid conditions were common, including hypertension (78% of patients), ischemic heart disease (65%), diabetes (38%), atrial fibrillation or flutter (32%), and chronic lung disease (23%). The majority of patients (61%) had not had coronary artery bypass graft surgery.

Most patients (83%) had New York Heart Association class III heart failure symptoms. A total of 67% had LBBB, and 55% had a QRS duration of 150 ms or longer.

Overall mortality was 0.8% at 30 days, 9.2% at 1 year, and 25.9% at 3 years. Overall rates of all-cause readmission were 10.2% at 30 days and 43.3% at 1 year. Rates of heart failure readmission were 2.2% at 30 days and 12.3% at 1 year.

In an unadjusted analysis of the data, rates of all adverse outcomes were significantly lower among patients who had LBBB and a QRS duration of 150 ms or more, the investigators said (JAMA 2013; 310:617-26; [doi:10.1001/jama.2013.8641]).

After the data were adjusted to account for numerous demographic and clinical factors, this difference remained robust. Patients who had LBBB and a QRS duration of 150 ms or greater had a 3-year mortality risk of 21%, compared with 27% for those with LBBB and QRS duration of 120-149 ms. Those with no LBBB and QRS duration of 150 ms or greater had an adjusted 3-year mortality risk of 31%), and patients with no LBBB and QRS durations of 120-149 ms had a 3-year risk of 32%. All differences were significant.

Patients with no LBBB and a long QRS duration, those with LBBB and a short QRS duration, and those with no LBBB and a short QRS duration consistently had higher risks of all adverse outcomes.

"Our real-world data add to the increasing body of evidence that patients with LBBB have better outcomes after CRT," Dr. Peterson and her associates said.

This study was supported by the U.S. Agency for Healthcare Research and Quality and the American College of Cardiology Foundation. Dr. Peterson reported serving as a consultant for Merck, and her associates reported numerous ties to industry sources.