WASHINGTON, DC — Could longer QRS duration be a biomarker for adverse outcomes after implantation with a continuous-flow left ventricular assist device (LVAD)? New research says yes. Maybe.
A retrospective analysis of 190 LVAD patients without cardiac resynchronization therapy (CRT) showed that, after adjustment for age and cardiomyopathy type, those with a QRS duration >150 ms had a 2.5-times higher risk for the primary composite outcome of all-cause mortality and CV readmissions postimplant vs those with a QRS duration <150 ms[1].
These findings were presented in a poster here at the International Society for Heart and Lung Transplantation (ISHLT) 2016 Scientific Sessions by Dr Xingchen Mai (Columbia University, New York City).
"Some people have thought that when you put in an LVAD, maybe those with long QRS would not have that worse long-term survival because you're unloading the LV," Mai told heartwire from Medscape. "But our theory at this point is that while you unload the LV, you leave the [right ventricle] RV unprotected."
Dr Mike Morrow (University of Minnesota Medical Center, Minneapolis) commented to heartwire that "this is an important study" but admitted he was a little surprised by the strength of the results.
"They're saying there's a correlation between longer QRS complex and worsening morbidity. And being that it's a poster, I figured it would be a small finding in a very small patient population," said Morrow, who was not involved with this research. "But after looking over everything, I can see that this has very valid data."
QRS Effect on LVAD Outcomes "Not Well Documented"
In his presentation, Mai noted that it's been shown that patients with chronic heart failure and a wide QRS "don't do so well" vs those with a narrow QRS. "And that's why CRT was created as a major therapy for this population."
But in terms of patients with an LVAD, whether QRS duration affects outcomes "hasn't been well documented before," he said.
The investigators first examined records for all 343 patients who received a continuous-flow LVAD at their center from May 2004 to October 2014. After excluding those who had active CRT, the final analysis included 190 patients (80% men; mean age 57.7 years). Of these, 47.2% had an ischemic cardiomyopathy.
An ECG was administered at time of LVAD implant and showed that 74.2% of the participants had a shorter QRS duration vs 25.8% who had longer QRS duration.
In addition, 37% of the wide-QRS-duration group had a left bundle branch block (LBBB), 16% had a right bundle branch block (RBBB), 18% had intraventricular conduction delay (IVCD), and 29% had predominantly RV pacing.
Those with longer QRS duration had significantly lower event-free survival up to 1250 days postimplant compared with those with shorter duration (P=0.03).
Modifiable Target?
The unadjusted hazard ratio (HR) for mortality/CV readmissions not related to pump malfunction was 2.91 for the longer-QRS-duration group vs the shorter-duration group (95% CI 1.48–5.73). The fully adjusted HR was 2.61 for the group with longer QRS duration (95% CI 1.28–5.29).
"Whether CRT can improve this outcome in LVAD recipients remains to be investigated," said Mai. "Is this a modifiable target?"
He added that more research is now needed to clear up these questions. And in fact, his team has just finished looking at all of the LVAD participants—including those with CRT. Those results are expected to be reported soon, but Mai teased that CRT didn't provide "that much of a difference" in outcomes for those with wide QRS. "Maybe the way we currently pace people with CRT isn't the right way to pace them," he said.
"One of the takeaways is that we may need to reconsider whether we need to rush to put in different devices after people come out with an LVAD. Different institutions behave differently," said Mai, noting that it's not routine at Columbia to put CRT into those with LVADs.
"I also think we need to think about other ways to try to save the RV in these patients. We're doing a great job at preserving the LV with an LVAD, but the RV gets neglected. In those with a wider QRS, maybe there's another way to pace the RV."
Morrow commented that although more research into the mechanisms behind the findings are definitely needed, this study provides at least "a pebble's worth of ripples" that are worth looking into. And he's excited for what comes next.
"This is just the tip of the iceberg; it's time now to go find out why these outcomes occurred," he said. "I deal with a lot of heart transplants, and we usually go to LVAD before transplant in the majority of our patients. Hopefully this is the [information needed] that's going to get us into that mode where they can live long enough to receive a heart transplant."
The study was funded by Lisa and Mark Schwartz and the Program to Reverse Heart Failure at New York Presbyterian Hospital/Columbia University. Mai reports no relevant financial disclosures; disclosures for the coauthors are listed in the abstract. Morrow reports no relevant financial relationships.
Follow Deborah Brauser on Twitter: @heartwireDeb. For more from theheart.org, follow us on Twitter and Facebook.
Heartwire from Medscape © 2016 Medscape, LLC
Cite this: Wider QRS Duration May Signal Increased Mortality, CV Readmission After LVAD Implantation - Medscape - May 03, 2016.
Comments