Meta-analyses and randomized trials investigating percutaneous coronary intervention of chronic total occlusions: what is left to explore?

The field of percutaneous coronary intervention of coronary chronic total occlusions (CTO PCI) is highly dynamic. This is mainly illustrated by the large number of technical advances that have propelled success rates of CTO PCI from 60–70% to as high as >90% in recent (selected) case series (1). However, the rationale for performing CTO PCI is currently largely based on observational data and untested hypotheses. Observational studies have suggested a reduction in the need for coronary artery bypass graft surgery (CABG), a reduced incidence of ventricular arrhythmias, and even reduced mortality after successful CTO PCI (2-6). Further hypothesis-generating research was recently published by our group in the form of a meta-analysis of observational studies investigating the evolution of left ventricular ejection fraction (LVEF) and left ventricular end diastolic volume (LVEDV) after CTO PCI (7). This study indicated a significant increase in LVEF of 4.44% [95% confidence interval (CI): 3.52–5.35%, P<0.01] after successful CTO PCI at a follow-up duration ranging from 1 to 36 months in 34 studies which included a total of 2,243 patients. Moreover, LVEDV was reduced by 6.14 mL/m2 in a meta-analysis of eight studies comprising 412 patients that evaluated LVEDV after successful CTO PCI.