An assessment of implantable cardioverter-defibrillators (ICDs) released by the Agency for Healthcare Research and Quality gave the devices a thumbs up for primary prevention of sudden cardiac death (SCD) compared with no ICD therapy.

Evaluators reviewed studies published through Dec. 4, 2012, on MEDLINE and through the third quarter of 2012 on the Cochrane Central Trial Registry that addressed the clinical effectiveness of ICDs implanted in patients who have risk factors for SCD but have yet to experience sustained ventricular tachyarrhythmia.

They found high strength of evidence that ICDs offered a benefit for reducing all-cause mortality and for reducing SCD compared with no ICD therapy. The number needed to treat to prevent one death ranged from 6.2 to 22 at follow-ups of three to seven years, while the number needed to treat to prevent one arrhythmic death was two to three.

Evidence also was deemed strong for assessing inhospital adverse event rates. They placed early adverse event rates at 3 percent and serious adverse event rates at 1 percent. Based on “moderate strength of evidence,” they found 3 to 21 percent of patients experienced at least one inappropriate shock within one- to five-year follow-up.

Researchers also evaluated trials for cardiac resynchronization therapy and concluded there was insufficient evidence comparing all-cause mortality for patients who received cardiac resynchronization therapy and those who received only ICD therapy for primary prevention.

“Future research is needed to address comparative effectiveness for quality of life and other patient reported outcomes and to explore treatment heterogeneity according to baseline risk,” they recommended. “Consistent reporting of rates of SCD in the non-ICD trial arms would facilitate an assessment of how the mortality benefit may be correlated with baseline risk.”

The technology assessment report, “Assessment on Implantable Defibrillators and the Evidence for Primary Prevention of Sudden Cardiac Death,” is available here.