Real life experience of defibrillators lives up to clinical trial expectations

By Piriya Mahendra, medwireNews Reporter

There is no significant difference in survival between clinical trial patients who receive an implantable cardioverter (ICD) and clinical registry patients who receive a primary prevention ICD, researchers suggest.

Sana Al-Khatib (Duke Clinical Research Institute, Durham, North Carolina, USA) and co-authors say that their findings support the continued use of primary prevention ICDs in clinical practice.

The retrospective analysis included patients who were enrolled in the National Cardiovascular Data ICD Registry between January 1, 2006, and December 31, 2007, and who met the criteria of either the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II; 2464 propensity score-matched patients) or the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT; 3352 propensity score-matched patients). Mortality data for the registry patients were collected through December 31, 2009.

The median follow-up time in MADIT-II SCD-HeFT, and the ICD Registry was 19.5, 46.1, and 35.2 months, respectively.

Khatib et al found that patients in the National Cardiovascular Data ICD Registry were significantly older and had a higher burden of comorbidities than those eligible for enrolment in the clinical trials.

In the matched cohorts, there was no significant difference in survival between MADIT-II-like patients in the registry and MADIT-II patients randomized to receive an ICD, at 2-year mortality rates of 12.9% versus 15.6%.. This corresponded to a nonsignificant adjusted hazard ratio of 1.06.

Likewise, the survival among registry patients eligible for enrolment in SCD-HeFT-like registry patients was not significantly different from survival among patients randomly allocated to receive ICD therapy in SCD-HeFT, at 3-year mortality rates of 17.3 and 17.4%, respectively. This corresponded to a nonsignificant hazard ratio of 1.16.

"We demonstrated that the adjusted survival of MADIT-II-like and SCD-HeFT-like patients who received a primary prevention ICD in clinical practice was not significantly different from the survival of patients who received an ICD in the clinical trials," write the authors.

"But [it] was significantly greater than the survival of trial patients randomized to receive medical therapy only," they continue in JAMA. "These findings were observed in the overall studied population as well as in patients aged 65 years and older."

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