CardioExchange Archive

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Cardiac-resynchronization therapy (CRT) has been shown to be beneficial in heart failure (HF) patients with a wide QRS interval. These benefits have not been reproduced so far in patients with narrow QRS intervals, though many such patients have ventricular dyssynchrony. Now a new study, presented at the European Society of Cardiology in Amsterdam and published simultaneously in the New England Journal of Medicine, once again has failed to find benefits for CRT in a broader patient population.

The EchoCRT Study Group randomized HF patients with a QRS duration < 130 msec and left ventricular dyssnchrony upon echocardiography. All patients received a CRT-D device; half the patients were randomized to have the CRT feature activated.

The study was stopped prematurely after 809 patients had been randomized and followed for nearly 20 months.

• The primary endpoint (composite of death from any cause or first hospitalization for worsening HF) occurred in 28.7% of the CRT group versus 25.2% of the controls (HR 1.20, CI 0.92-1.57, p=0.15)
• There was a significant increase in mortality in the CRT group :11.1% versus 6.4%, CI 1.11-2.93, p=0.02)

There were also more inappropriate shocks in the CRT group and more adverse events — largely driven by lead-related complications — in the CRT group.

“Our results reinforce the notion that, at least until new methods of assessment are developed, QRS width with or without mechanical dyssynchrony) remains the primary determinant of response to CRT,” the authors write.

Definitive Results

In an accompanying editorial, Clyde Yancy and John McMurray say the results of the trial “were definitive: CRT is not beneficial in patients with HF and a narrow QRS complex and may be harmful.” They also sought to emphasize that “…CRT itself is not without risk, including periprocedural complications, lead-related issues, and inadvertent right ventricular pacing that aggravates left ventricular dysfunction.”

CRT is unwarranted in patients with a QRS duration < 120 msec, while for patients between 120 and 130 msec, current guidelines should be followed, though echo should not be used to identify patients who may benefit from CRT.

“Today, in addition to measurement of left ventricular ejection fraction, the simple 12-lead surface ECG remains the only evidence-based means of identifying patients who may obtain the substantial benefits of CRT.”

See also Edward J. Schloss’s perspective on EchoCRT.