Background Ageing, left ventricle hypertrophy (LVH), diabetes and pregnancy are well recognised risk factors that increase the prevalence of ischaemic events and were linked to poor clinical recovery following acute myocardial infarction. The coexistence of these risk factors with ischaemic heart disease (IHD) deteriorates disease prognosis and could potentially lead to fatal arrhythmias and heart failure. The objective of this study was to investigate the vulnerability of hearts with comorbidities including ageing, LVH, diabetes and pregnancy to ischaemic insult and their response to heart cardiac protection induced by pacing postconditioning procedure.

Methods Hearts isolated from aged, spontaneously hypertensive and diabetic male and female rats and hearts from pregnant female rats (n=8 per group) were subjected to coronary occlusion followed by reperfusion using a modified Langendorff system. Hemodynamics data were computed digitally and cardiac damaged was accessed by measurements of infarct size and cardiac enzyme release.

Results There were no significant differences in the vulnerability of all hearts to the ischaemic insult compared to control. Cardiac hemodynamics were significantly (p<0.001) improved while infarct size and cardiac enzymes were significantly (p<0.001) reduced in the hearts isolated from aged female rats and female rats with hypertrophied hearts subjected to PPC. Aged or hypertrophied male hearts were however not protected. Mover over the protective properties of PPC were lost in diabetic male and female hearts yet retained in hearts from pregnant rats.

Conclusions Ageing, LVH, diabetes mellitus and pregnancy do not affect cardiac vulnerability to ischaemic insult. PPC mediates cardioprotection in a gender specific manner in hearts from aged and spontaneously hypertensive rats. Diabetes mellitus however provokes the protective effects of PPC in equally both genders. Finally, PPC is a novel cardioprotective manoeuvre in hearts from pregnant female rats.