This is probably not the ideal route up Heartbeat Peak from the east. Nevertheless, it is the one we ended up taking, so there you go. This started as an ascent to the Iceberg Lake cirque east of the Divide, north of Heartbeat. Our plan was to climb the Icebox Express route (moderate snow), but we got sidetracked....
Start at the East Portal Trailhead and hike two miles on the South Boulder Creek trail to a small swampy area. The trail makes a 90-degree turn to the south shortly after this. Look for a small bridge on the right side of the trail with a small wooden sign on a tree. The swamp is 0.2 miles beyond this.
The Northeast Ridge from just above the rock outcropping at 11,400'.
From the swamp, bushwhack directly west following the stream drainage between two hills. The stream drains Clayton Lake and the Iceberg Lakes and the southern (left) hillside eventually becomes the northeast ridge route.
Find your way as best you can up the ridge. In the winter, there is a snowy gully which is steep enough and narrow enough to collect quite a lot of snow. I don't know what summer conditions are like, nor if this is the easiest route. From the top of the gully, angle right through lower-angle terrain to the base of a large, bare slope crowned with a rock outcropping. Climb to the base of the outcropping and angle right to surmount a low section. Walk west and uphill to the top of the outcropping. You are now at the base of the ridge proper and done with the hardest part of the climb.
From here, it is a relatively easy mile and a half to the Divide. The ridge features several false summits in a nice tundra setting replete with picas, moss and wildflowers (in season). Surmount the final false summit to the Divide. Turn left (south) and walk one third of a mile and a hundred feet of gain to the gentle summit of Heartbeat Peak.
The final and easiest stretch of the northeast ridge.
Be prepared for a steep scramble on scree and snow on the lower portion of the route. Sturdy shoes in summer are a must. Standard day-hiking gear otherwise.
In the winter, the lower route is deeply snowed and snowshoes will make your life much easier. The upper portions of the route are often windy and full-winter conditions may apply. Crampons and ice axe may be neccessary.