H-ISDN meta-analysis
In patients with HFrEF in randomised trials of hydralazine–isosorbide dinitrate, hydralazine–isosorbide dinitrate reduced clinical outcomes compared with control.
Three trials forty years apart, pooled to buy the power none of them had: the mortality signal is consistent (I2 = 0%) and survives a Mantel-Haenszel check, which is the strongest case yet for a drug pair the guidelines restrict to one group of patients. The hospitalisation result is the weak half — it holds only under fixed effects, and the heterogeneity behind it is real: A-HeFT stopped early for benefit, H-HeFT saw no effect at all. The trials also differ in what background therapy meant, from digitalis and diuretics in 1980 to four-pillar therapy in 2025, so the pooled estimate answers a question no single era asked.