Can Synthroid Usage Cause Hypertension And Heart Problems?

Hello, My question is about hypothyroid plus cardiovascular changes. Age 55, hgt 5 7 wgt 163 lb; hypothyroid since age 22 treated with Synthroid only. Recent M.I. with one sided hypertension now, and metabolic syndrome. I ve never felt clinically improved on Synthroid, just marginally, all these years.. still serious fatigued, wgt gain, leg/foot cramps, muscle weakness, dry skin/hair, brain fog moments, generally weak and weary. Could t3 supplement, like Cytomel, help me with these lingering hypo symptoms? Am I looking at high risks, due to heart attack recently? I understand that subclinical hypothyroid can eventually lead to hypertension and even some of these nasty cardiovascular deteriorations. Would like to correct any lingering under treated thyroid deficiency, as I ve modified to heart diet, taking gold standard cardiac meds now also. Thank you.