Objectives To investigate survival in patients with Eisenmenger syndrome based on a systematic review of the literature and reanalysis of data. We specifically tested the hypothesis that previous publications have been subject to immortal time bias, confounding survival analyses.

Methods A systematic review of the literature was performed to evaluate survival in treatment naïve patients with Eisenmenger syndrome and standardised mortality ratios were calculated. Furthermore, we used a contemporary cohort of 219 treatment naïve patients with Eisenmenger syndrome from the own institution as a comparison group.

Results Overall, 12 studies (published 1971–2013) were identified, including a total of 1131 patients. Only one study seemed to deal appropriately with immortal time bias in this setting. All other studies did not account for this effect, thus overestimating survival prospects of patients with Eisenmenger syndrome by up to 20 years. After accounting for this effect we found high standardised mortality ratios, a 10-year mortality rate approaching 30–40% and no evidence of superior survival prospects of current era patients compared with those seen in the 1970s, 1980s and 1990s. Only, a historical Eisenmenger-cohort from the 1950s/1960s had worse survival.

Conclusions The current analysis challenges the traditional view of benign survival prospects of patients with Eisenmenger syndrome. In addition, survival prospects do not seem to have considerably improved over the last decades in untreated patients. These results support a proactive treatment strategy including a more aggressive approach trying to avoid the development of the condition.